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Analytica Chimica Acta (v.750, #)
Foreword for Analytica Chimica Acta Volume 750
by Paul Worsfold; Ulli Krull; Alan Townshend (pp. 1-2).
Foreword for Analytica Chimica Acta Volume 750
by Paul Worsfold; Ulli Krull; Alan Townshend (pp. 1-2).
Recent advances and future prospects of mesofluidic Lab-on-a-Valve platforms in analytical sciences – A critical review by Manuel Miró; Elo Harald Hansen (pp. 3-15).
Display Omitted► Lab-on-a-Valve (LOV) is a pressure driven mesofluidic system capitalizing on programmable flow. ► LOV assays meet green chemical principles. ► LOV fosters on-chip sample processing. ► LOV facilitates fully integration of analytical procedures. ► LOV is able to cope with real-life bioanalytical assays.Miniaturization and automation in analytical sciences have evolved tremendously over the past decade within the framework of green analytical chemistry. This manuscript outlines the unrivalled merits of advanced flow methodology capitalizing on mesofluidic platforms for the simplification and acceleration of the overall analytical process. Introduced back in 2000, the Lab-on-a-Valve concept (LOV), allied to sequential injection analysis, has emerged as an appealing downscaled analytical tool for pressure-driven sampling at the low μL level. Not the least, for advanced on-chip sample processing involving renewable micro-solid phase extraction (so-called bead injection analysis), non-chromatographic speciation or chemical vapor generation using programmable flow, for optical and electrochemical detection on-chip including optosensing approaches, or as a front end to modern detection equipment or column separation systems.It is the intention of this work to offer the authors’ own critical vision as to where the field of LOV is being directed on the basis of the survey of the current state-of-the art of mesofluidic systems and identify what are the major cutting-edge challenges to be yet undertaken and what opportunities are offered by LOV for real-world applications that might not be at present tackled by lab-on-a-chip microfluidic approaches.
Keywords: Lab-on-a-Valve; Automation; Miniaturization; Sample processing; Meso/microfluidic systems
Recent advances and future prospects of mesofluidic Lab-on-a-Valve platforms in analytical sciences – A critical review by Manuel Miró; Elo Harald Hansen (pp. 3-15).
Display Omitted► Lab-on-a-Valve (LOV) is a pressure driven mesofluidic system capitalizing on programmable flow. ► LOV assays meet green chemical principles. ► LOV fosters on-chip sample processing. ► LOV facilitates fully integration of analytical procedures. ► LOV is able to cope with real-life bioanalytical assays.Miniaturization and automation in analytical sciences have evolved tremendously over the past decade within the framework of green analytical chemistry. This manuscript outlines the unrivalled merits of advanced flow methodology capitalizing on mesofluidic platforms for the simplification and acceleration of the overall analytical process. Introduced back in 2000, the Lab-on-a-Valve concept (LOV), allied to sequential injection analysis, has emerged as an appealing downscaled analytical tool for pressure-driven sampling at the low μL level. Not the least, for advanced on-chip sample processing involving renewable micro-solid phase extraction (so-called bead injection analysis), non-chromatographic speciation or chemical vapor generation using programmable flow, for optical and electrochemical detection on-chip including optosensing approaches, or as a front end to modern detection equipment or column separation systems.It is the intention of this work to offer the authors’ own critical vision as to where the field of LOV is being directed on the basis of the survey of the current state-of-the art of mesofluidic systems and identify what are the major cutting-edge challenges to be yet undertaken and what opportunities are offered by LOV for real-world applications that might not be at present tackled by lab-on-a-chip microfluidic approaches.
Keywords: Lab-on-a-Valve; Automation; Miniaturization; Sample processing; Meso/microfluidic systems
Non-invasive glucose monitoring technology in diabetes management: A review by Sandeep Kumar Vashist (pp. 16-27).
Display Omitted► We review the advances in non-invasive glucose monitoring in last two decades. ► Initially, the various non-invasive glucose monitoring techniques are described. ► Thereafter, the non-invasive glucose monitoring devices are presented. ► The future trends in technology are discussed in the last section.The frequent monitoring of glucose is an essential part of diabetes management. Despite the fact that almost all the commercially successful blood glucose monitoring devices are invasive, there is an immense need to develop non-invasive glucose monitoring (NGM) devices that will alleviate the pain and suffering of diabetics associated with the frequent pricking of skin for taking the blood sample for glucose testing. There have been numerous developments in the field of NGM during the last decade, which stress the need for a critical review. This manuscript aims to review the various NGM techniques and devices. The challenges and future trends in NGM are also discussed.
Keywords: Non-invasive; Glucose monitoring; Techniques; Devices; Diabetes
Non-invasive glucose monitoring technology in diabetes management: A review by Sandeep Kumar Vashist (pp. 16-27).
Display Omitted► We review the advances in non-invasive glucose monitoring in last two decades. ► Initially, the various non-invasive glucose monitoring techniques are described. ► Thereafter, the non-invasive glucose monitoring devices are presented. ► The future trends in technology are discussed in the last section.The frequent monitoring of glucose is an essential part of diabetes management. Despite the fact that almost all the commercially successful blood glucose monitoring devices are invasive, there is an immense need to develop non-invasive glucose monitoring (NGM) devices that will alleviate the pain and suffering of diabetics associated with the frequent pricking of skin for taking the blood sample for glucose testing. There have been numerous developments in the field of NGM during the last decade, which stress the need for a critical review. This manuscript aims to review the various NGM techniques and devices. The challenges and future trends in NGM are also discussed.
Keywords: Non-invasive; Glucose monitoring; Techniques; Devices; Diabetes
Inorganic monoliths in separation science: A review by Zarah Walsh; Brett Paull; Mirek Macka (pp. 28-47).
The practical application of rigid, macro-porous organic polymer and silica based monolithic stationary phases as separation media has been described in the literature since 1992 and 1996, respectively. Today these materials are extensively used in chromatography and electrochromatography and several detailed reviews appear annually describing these materials, their synthesis and application. To compliment these publications, this review focuses upon the less commonly utilised materials for monolith synthesis, both those that have already been applied within separation science, and those that have found applications elsewhere, such as catalysis and water filtration, but have the clear potential to be explored as novel stationary phases in the near future. For the purpose of the review monoliths formed from these various alternative materials will be termed ‘Exotic Monoliths’, as these new substrates in many cases have only just begun to be explored for chromatographic separations, and in many instances have unusual and highly selective surface chemistries, which are attractive in terms of broadening the choice of monolithic materials for separation science. An extensive range of monolithic materials based on the following elements and their compounds (mostly oxides) are covered: Zr, Ti, Al, Hf, C, Au, Ag, Ce, Ge and hydroxyapatite, together with their relevant properties, methods of synthesis, and current and potential applications in separation science.
Keywords: Monoliths; Monolithic stationary phases; Inorganic materials; Separation science; Chromatography
Inorganic monoliths in separation science: A review by Zarah Walsh; Brett Paull; Mirek Macka (pp. 28-47).
The practical application of rigid, macro-porous organic polymer and silica based monolithic stationary phases as separation media has been described in the literature since 1992 and 1996, respectively. Today these materials are extensively used in chromatography and electrochromatography and several detailed reviews appear annually describing these materials, their synthesis and application. To compliment these publications, this review focuses upon the less commonly utilised materials for monolith synthesis, both those that have already been applied within separation science, and those that have found applications elsewhere, such as catalysis and water filtration, but have the clear potential to be explored as novel stationary phases in the near future. For the purpose of the review monoliths formed from these various alternative materials will be termed ‘Exotic Monoliths’, as these new substrates in many cases have only just begun to be explored for chromatographic separations, and in many instances have unusual and highly selective surface chemistries, which are attractive in terms of broadening the choice of monolithic materials for separation science. An extensive range of monolithic materials based on the following elements and their compounds (mostly oxides) are covered: Zr, Ti, Al, Hf, C, Au, Ag, Ce, Ge and hydroxyapatite, together with their relevant properties, methods of synthesis, and current and potential applications in separation science.
Keywords: Monoliths; Monolithic stationary phases; Inorganic materials; Separation science; Chromatography
Applications of polydimethylsiloxane in analytical chemistry: A review by Suresh Seethapathy; Tadeusz Górecki (pp. 48-62).
Display Omitted► Polydimethylsiloxane (PDMS) has numerous applications in analytical chemistry. ► Sorptive properties of PDMS are used primarily in sampling. ► Partitioning properties are used in separations. ► Permeability of PDMS forms the basis for sample introduction and passive sampling. ► Advantageous mechanical properties are used in lab-on-a-chip devices.Silicones have innumerable applications in many areas of life. Polydimethylsiloxane (PDMS), which belongs to the class of silicones, has been extensively used in the field of analytical chemistry owing to its favourable physicochemical properties. The use of PDMS in analytical chemistry gained importance with its application as a stationary phase in gas chromatographic separations. Since then it has been used in many sample preparation techniques such as solid phase microextraction (SPME), stir bar sorptive extraction (SBSE), thin-film extraction, permeation passive sampling, etc. Further, it is gaining importance in the manufacturing of lab-on-a-chip devices, which have revolutionized bio-analysis. Applications of devices containing PDMS and used in the field of analytical chemistry are reviewed in this paper.
Keywords: Abbreviations; CMV; cytomegalovirus; DNA; deoxyribonucleic acid; ESE; equilibrium sorptive enrichment; GC; gas chromatography; GC–IR-C-MS; gas chromatography–isotope ratio-combustion-mass spectrometry; GLC; gas liquid chromatography; GADPH; glyceraldehyde 3-phosphate dehydrogenase; GUT; Gdańsk University of Technology; HSSE; headspace sorptive extraction; LOC; lab-on-a-chip; LTPRI; linear temperature-programmed retention index; MESCO; membrane-enclosed sorptive coating; MESI; membrane extraction with a sorbent interface; MEMS; microelectromechanical system; MIMS; membrane inlet mass spectrometry; MOSFET; metal oxide semiconductor field effect transistor; NIOSH; National Institute of Standards and Health; OCP; organochlorine pesticides; OSHA; Occupational Safety and Health Administration; PAH; polyaromatic hydrocarbons; PCB; polychlorinated biphenyls; PCR; polymerase chain reaction; PDMS; polydimethylsiloxane; PTFE; polytetrafluoroethylene; SBSE; stir bar sorptive extraction; SiSTEx; solvent in silicone tube extraction; SMSE; silicon membrane sorptive extraction; SPME; solid phase microextraction; STE; sorptive tape extraction; sVOC; semi-volatile organic compound; TWA; time-weighted average; US-EPA; United States Environmental Protection Agency; VOC; volatile organic compound; WMS; Waterloo Membrane SamplerPolydimethylsiloxane (PDMS); Passive sampling; Sorption; Permeability; Extraction
Applications of polydimethylsiloxane in analytical chemistry: A review by Suresh Seethapathy; Tadeusz Górecki (pp. 48-62).
Display Omitted► Polydimethylsiloxane (PDMS) has numerous applications in analytical chemistry. ► Sorptive properties of PDMS are used primarily in sampling. ► Partitioning properties are used in separations. ► Permeability of PDMS forms the basis for sample introduction and passive sampling. ► Advantageous mechanical properties are used in lab-on-a-chip devices.Silicones have innumerable applications in many areas of life. Polydimethylsiloxane (PDMS), which belongs to the class of silicones, has been extensively used in the field of analytical chemistry owing to its favourable physicochemical properties. The use of PDMS in analytical chemistry gained importance with its application as a stationary phase in gas chromatographic separations. Since then it has been used in many sample preparation techniques such as solid phase microextraction (SPME), stir bar sorptive extraction (SBSE), thin-film extraction, permeation passive sampling, etc. Further, it is gaining importance in the manufacturing of lab-on-a-chip devices, which have revolutionized bio-analysis. Applications of devices containing PDMS and used in the field of analytical chemistry are reviewed in this paper.
Keywords: Abbreviations; CMV; cytomegalovirus; DNA; deoxyribonucleic acid; ESE; equilibrium sorptive enrichment; GC; gas chromatography; GC–IR-C-MS; gas chromatography–isotope ratio-combustion-mass spectrometry; GLC; gas liquid chromatography; GADPH; glyceraldehyde 3-phosphate dehydrogenase; GUT; Gdańsk University of Technology; HSSE; headspace sorptive extraction; LOC; lab-on-a-chip; LTPRI; linear temperature-programmed retention index; MESCO; membrane-enclosed sorptive coating; MESI; membrane extraction with a sorbent interface; MEMS; microelectromechanical system; MIMS; membrane inlet mass spectrometry; MOSFET; metal oxide semiconductor field effect transistor; NIOSH; National Institute of Standards and Health; OCP; organochlorine pesticides; OSHA; Occupational Safety and Health Administration; PAH; polyaromatic hydrocarbons; PCB; polychlorinated biphenyls; PCR; polymerase chain reaction; PDMS; polydimethylsiloxane; PTFE; polytetrafluoroethylene; SBSE; stir bar sorptive extraction; SiSTEx; solvent in silicone tube extraction; SMSE; silicon membrane sorptive extraction; SPME; solid phase microextraction; STE; sorptive tape extraction; sVOC; semi-volatile organic compound; TWA; time-weighted average; US-EPA; United States Environmental Protection Agency; VOC; volatile organic compound; WMS; Waterloo Membrane SamplerPolydimethylsiloxane (PDMS); Passive sampling; Sorption; Permeability; Extraction
Active cellular sensing with quantum dots: Transitioning from research tool to reality; a review by James B. Delehanty; Kimihiro Susumu; Rachel L. Manthe; W. Russ Algar; Igor L. Medintz (pp. 63-81).
Display Omitted► Quantum dots (QDs) have evolved beyond mere cellular labeling reagents. ► Significant advances have been made in QD materials, surface coatings and bioconjugation. ► Cellular targeting/delivery has been achieved using polymers, peptides, proteins. ► Numerous QD-based sensing applications: extracellular, membrane, intracellular.The application of luminescent semiconductor quantum dots (QDs) within a wide range of biological imaging and sensing formats is now approaching its 15th year. The unique photophysical properties of these nanomaterials have long been envisioned as having the potential to revolutionize biosensing within cellular studies that rely on fluorescence. However, it is only now that these materials are making the transition towards accomplishing this goal. With the idea of understanding how to actively incorporate QDs into different types of cellular biosensing, we review the progress in many of the areas relevant to achieving this goal. This includes the synthesis of the QDs themselves, with an emphasis on minimizing potential toxicity, along with the general methods for making these nanocrystalline structures stable in aqueous media. We next survey some methods for conjugating QDs to biomolecules to allow them to participate in active biosensing. Lastly, we extensively review many of the applications where QDs have been demonstrated in an active role in cellular biosensing. These formats cover a wide range of possibilities including where the QDs have contributed to: monitoring the cell's interaction with its extracellular environment; elucidating the complex molecular interplay that characterizes the plasma membrane; understanding how cells continuously endocytose and exocytose materials across the cellular membrane; visualizing organelle trafficking; and, perhaps most importantly, monitoring the intracellular presence of target molecules such as nucleic acids, nutrients, cofactors, and ions or, alternatively, intracellular responses to external changes in the environment. We illustrate these processes with examples from the recent literature and focus on what QDs can uniquely contribute along with discussing the benefits and liabilities of each sensing strategy. A perspective on where this field is expected to develop in both the near and long-term is also provided.
Keywords: Quantum dot; Biosensor; Fluorescence; Endocytosis; Imaging; Theranostics
Active cellular sensing with quantum dots: Transitioning from research tool to reality; a review by James B. Delehanty; Kimihiro Susumu; Rachel L. Manthe; W. Russ Algar; Igor L. Medintz (pp. 63-81).
Display Omitted► Quantum dots (QDs) have evolved beyond mere cellular labeling reagents. ► Significant advances have been made in QD materials, surface coatings and bioconjugation. ► Cellular targeting/delivery has been achieved using polymers, peptides, proteins. ► Numerous QD-based sensing applications: extracellular, membrane, intracellular.The application of luminescent semiconductor quantum dots (QDs) within a wide range of biological imaging and sensing formats is now approaching its 15th year. The unique photophysical properties of these nanomaterials have long been envisioned as having the potential to revolutionize biosensing within cellular studies that rely on fluorescence. However, it is only now that these materials are making the transition towards accomplishing this goal. With the idea of understanding how to actively incorporate QDs into different types of cellular biosensing, we review the progress in many of the areas relevant to achieving this goal. This includes the synthesis of the QDs themselves, with an emphasis on minimizing potential toxicity, along with the general methods for making these nanocrystalline structures stable in aqueous media. We next survey some methods for conjugating QDs to biomolecules to allow them to participate in active biosensing. Lastly, we extensively review many of the applications where QDs have been demonstrated in an active role in cellular biosensing. These formats cover a wide range of possibilities including where the QDs have contributed to: monitoring the cell's interaction with its extracellular environment; elucidating the complex molecular interplay that characterizes the plasma membrane; understanding how cells continuously endocytose and exocytose materials across the cellular membrane; visualizing organelle trafficking; and, perhaps most importantly, monitoring the intracellular presence of target molecules such as nucleic acids, nutrients, cofactors, and ions or, alternatively, intracellular responses to external changes in the environment. We illustrate these processes with examples from the recent literature and focus on what QDs can uniquely contribute along with discussing the benefits and liabilities of each sensing strategy. A perspective on where this field is expected to develop in both the near and long-term is also provided.
Keywords: Quantum dot; Biosensor; Fluorescence; Endocytosis; Imaging; Theranostics
NMR and pattern recognition methods in metabolomics: From data acquisition to biomarker discovery: A review by Agnieszka Smolinska; Lionel Blanchet; Lutgarde M.C. Buydens; Sybren S. Wijmenga (pp. 82-97).
.Display Omitted► Procedures for acquisition of different biofluids by NMR. ► Recent developments in metabolic profiling of different biofluids by NMR are presented. ► The crucial steps involved in data preprocessing and multivariate chemometric analysis are reviewed. ► Emphasis is given on recent findings on Multiple Sclerosis via NMR and pattern recognition methods.Metabolomics is the discipline where endogenous and exogenous metabolites are assessed, identified and quantified in different biological samples. Metabolites are crucial components of biological system and highly informative about its functional state, due to their closeness to functional endpoints and to the organism's phenotypes. Nuclear Magnetic Resonance (NMR) spectroscopy, next to Mass Spectrometry (MS), is one of the main metabolomics analytical platforms. The technological developments in the field of NMR spectroscopy have enabled the identification and quantitative measurement of the many metabolites in a single sample of biofluids in a non-targeted and non-destructive manner. Combination of NMR spectra of biofluids and pattern recognition methods has driven forward the application of metabolomics in the field of biomarker discovery. The importance of metabolomics in diagnostics, e.g. in identifying biomarkers or defining pathological status, has been growing exponentially as evidenced by the number of published papers. In this review, we describe the developments in data acquisition and multivariate analysis of NMR-based metabolomics data, with particular emphasis on the metabolomics of Cerebrospinal Fluid (CSF) and biomarker discovery in Multiple Sclerosis (MScl).
Keywords: Metabolomics; NMR; Pattern recognition; Preprocessing; Biomarker discovery; Multiple Sclerosis
NMR and pattern recognition methods in metabolomics: From data acquisition to biomarker discovery: A review by Agnieszka Smolinska; Lionel Blanchet; Lutgarde M.C. Buydens; Sybren S. Wijmenga (pp. 82-97).
.Display Omitted► Procedures for acquisition of different biofluids by NMR. ► Recent developments in metabolic profiling of different biofluids by NMR are presented. ► The crucial steps involved in data preprocessing and multivariate chemometric analysis are reviewed. ► Emphasis is given on recent findings on Multiple Sclerosis via NMR and pattern recognition methods.Metabolomics is the discipline where endogenous and exogenous metabolites are assessed, identified and quantified in different biological samples. Metabolites are crucial components of biological system and highly informative about its functional state, due to their closeness to functional endpoints and to the organism's phenotypes. Nuclear Magnetic Resonance (NMR) spectroscopy, next to Mass Spectrometry (MS), is one of the main metabolomics analytical platforms. The technological developments in the field of NMR spectroscopy have enabled the identification and quantitative measurement of the many metabolites in a single sample of biofluids in a non-targeted and non-destructive manner. Combination of NMR spectra of biofluids and pattern recognition methods has driven forward the application of metabolomics in the field of biomarker discovery. The importance of metabolomics in diagnostics, e.g. in identifying biomarkers or defining pathological status, has been growing exponentially as evidenced by the number of published papers. In this review, we describe the developments in data acquisition and multivariate analysis of NMR-based metabolomics data, with particular emphasis on the metabolomics of Cerebrospinal Fluid (CSF) and biomarker discovery in Multiple Sclerosis (MScl).
Keywords: Metabolomics; NMR; Pattern recognition; Preprocessing; Biomarker discovery; Multiple Sclerosis
Elemental labelling combined with liquid chromatography inductively coupled plasma mass spectrometry for quantification of biomolecules: A review by Daniela Kretschy; Gunda Koellensperger; Stephan Hann (pp. 98-110).
Display Omitted► Survey of bio-analytical approaches utilizing biomolecule labelling. ► Detailed discussion of methodology and chemistry of elemental labelling. ► Biomedical and bio-analytical applications of elemental labelling. ► FI-ICP-MS and LC–ICP-MS for quantification of elemental labelled biomolecules. ► Review of selected applications.This article reviews novel quantification concepts where elemental labelling is combined with flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS) or liquid chromatography inductively coupled plasma mass spectrometry (LC–ICP-MS), and employed for quantification of biomolecules such as proteins, peptides and related molecules in challenging sample matrices. In the first sections an overview on general aspects of biomolecule quantification, as well as of labelling will be presented emphasizing the potential, which lies in such methodological approaches. In this context, ICP-MS as detector provides high sensitivity, selectivity and robustness in biological samples and offers the capability for multiplexing and isotope dilution mass spectrometry (IDMS). Fundamental methodology of elemental labelling will be highlighted and analytical, as well as biomedical applications will be presented. A special focus will lie on established applications underlining benefits and bottlenecks of such approaches for the implementation in real life analysis. Key research made in this field will be summarized and a perspective for future developments including sophisticated and innovative applications will given.
Keywords: Liquid chromatography; Flow injection analysis; Inductively coupled plasma mass spectrometry; Elemental labelling; Quantitative bio-analysis
Elemental labelling combined with liquid chromatography inductively coupled plasma mass spectrometry for quantification of biomolecules: A review by Daniela Kretschy; Gunda Koellensperger; Stephan Hann (pp. 98-110).
Display Omitted► Survey of bio-analytical approaches utilizing biomolecule labelling. ► Detailed discussion of methodology and chemistry of elemental labelling. ► Biomedical and bio-analytical applications of elemental labelling. ► FI-ICP-MS and LC–ICP-MS for quantification of elemental labelled biomolecules. ► Review of selected applications.This article reviews novel quantification concepts where elemental labelling is combined with flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS) or liquid chromatography inductively coupled plasma mass spectrometry (LC–ICP-MS), and employed for quantification of biomolecules such as proteins, peptides and related molecules in challenging sample matrices. In the first sections an overview on general aspects of biomolecule quantification, as well as of labelling will be presented emphasizing the potential, which lies in such methodological approaches. In this context, ICP-MS as detector provides high sensitivity, selectivity and robustness in biological samples and offers the capability for multiplexing and isotope dilution mass spectrometry (IDMS). Fundamental methodology of elemental labelling will be highlighted and analytical, as well as biomedical applications will be presented. A special focus will lie on established applications underlining benefits and bottlenecks of such approaches for the implementation in real life analysis. Key research made in this field will be summarized and a perspective for future developments including sophisticated and innovative applications will given.
Keywords: Liquid chromatography; Flow injection analysis; Inductively coupled plasma mass spectrometry; Elemental labelling; Quantitative bio-analysis
Determination of water soluble trace metals in airborne particulate matter using a dynamic extraction procedure with on-line inductively coupled plasma optical emission spectrometric detection by Andreas Limbeck; Christoph Wagner; Bernhard Lendl; Azam Mukhtar (pp. 111-119).
Display Omitted► FI-system for extraction of airborne particulate matter samples under dynamic conditions. ► On-line ICP-OES measurement of derived aqueous sample extracts. ► Fast, accurate and highly sensitive analysis of water soluble trace metal concentrations. ► Information about the kinetics of the leaching process accessible.A novel continuous-flow system for the dynamic extraction of water soluble metal fractions in airborne particulate matter (APM) with subsequent inductively coupled plasma optical emission spectrometric (ICP-OES) analysis of derived extracts is presented. The fully automated extraction system with on-line multi-element detection offers enhanced sensitivity when compared to batch-wise counterparts; additionally it provides information about the extraction process. With the developed procedure detection limits in the order of 1.5 (Ba) to 8.0 (Ni)ng extractable mass per investigated sample could be achieved, which translates to method detection limits for soluble metal concentrations in APM ranging from 0.2ngm−3 (Ba) to 0.9ngm−3 (Fe). Reproducibility of analysis was determined by replicate measurement ( n=6) of an APM sample with an aerodynamic diameter ≤10μm (PM10), derived results varied between 3.5% (Mn) and 12.1% (Ni) relative standard deviation. Method validation was accomplished by comparison of extracted soluble and remaining non-soluble fractions with the total metal contents of the investigated PM10 samples, showing an excellent mass balance for all elements. Application of the developed procedure for the analysis of water soluble metal fractions in PM10 samples ( n=16) from Linz (Austria) indicated a high variability of extractable fractions ranging from 11.7±7.2% (Fe) to 48.8±15.4% (Mn) of the total metal contents.
Keywords: Dynamic extraction procedure; On-line detection; Inductively coupled plasma optical emission spectrometry; Airborne particulate matter; Trace metals; Water soluble fraction
Determination of water soluble trace metals in airborne particulate matter using a dynamic extraction procedure with on-line inductively coupled plasma optical emission spectrometric detection by Andreas Limbeck; Christoph Wagner; Bernhard Lendl; Azam Mukhtar (pp. 111-119).
Display Omitted► FI-system for extraction of airborne particulate matter samples under dynamic conditions. ► On-line ICP-OES measurement of derived aqueous sample extracts. ► Fast, accurate and highly sensitive analysis of water soluble trace metal concentrations. ► Information about the kinetics of the leaching process accessible.A novel continuous-flow system for the dynamic extraction of water soluble metal fractions in airborne particulate matter (APM) with subsequent inductively coupled plasma optical emission spectrometric (ICP-OES) analysis of derived extracts is presented. The fully automated extraction system with on-line multi-element detection offers enhanced sensitivity when compared to batch-wise counterparts; additionally it provides information about the extraction process. With the developed procedure detection limits in the order of 1.5 (Ba) to 8.0 (Ni)ng extractable mass per investigated sample could be achieved, which translates to method detection limits for soluble metal concentrations in APM ranging from 0.2ngm−3 (Ba) to 0.9ngm−3 (Fe). Reproducibility of analysis was determined by replicate measurement ( n=6) of an APM sample with an aerodynamic diameter ≤10μm (PM10), derived results varied between 3.5% (Mn) and 12.1% (Ni) relative standard deviation. Method validation was accomplished by comparison of extracted soluble and remaining non-soluble fractions with the total metal contents of the investigated PM10 samples, showing an excellent mass balance for all elements. Application of the developed procedure for the analysis of water soluble metal fractions in PM10 samples ( n=16) from Linz (Austria) indicated a high variability of extractable fractions ranging from 11.7±7.2% (Fe) to 48.8±15.4% (Mn) of the total metal contents.
Keywords: Dynamic extraction procedure; On-line detection; Inductively coupled plasma optical emission spectrometry; Airborne particulate matter; Trace metals; Water soluble fraction
Ionic liquid-based ultrasound-assisted dispersive liquid–liquid microextraction followed high-performance liquid chromatography for the determination of ultraviolet filters in environmental water samples by Yufeng Zhang; Hian Kee Lee (pp. 120-126).
Display Omitted► [HMIM][FAP] was for the first time employed as extraction solvent in USA-DLLME. ► [HMIM][FAP] showed high extraction efficiency for UV filters in water. ► The new method avoided the use of highly toxic chlorinated extraction solvents. ► Fast extraction time relative to other methods was another advantage. ► Simple and efficient method with low LODs, good repeatability and linearity.In the present study, a rapid, highly efficient and environmentally friendly sample preparation method named ionic liquid-based ultrasound-assisted dispersive liquid–liquid microextraction (IL-USA-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for the extraction and preconcentration of four benzophenone-type ultraviolet (UV) filters ( viz. benzophenone (BP), 2-hydroxy-4-methoxybenzophenone (BP-3), ethylhexyl salicylate (EHS) and homosalate (HMS)) from three different water matrices. The procedure was based on a ternary solvent system containing tiny droplets of ionic liquid (IL) in the sample solution formed by dissolving an appropriate amount of the IL extraction solvent 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM][FAP]) in a small amount of water-miscible dispersive solvent (methanol). An ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution, which markedly increased the extraction efficiency and reduced the equilibrium time. Various parameters that affected the extraction efficiency (such as type and volume of extraction and dispersive solvents, ionic strength, pH and extraction time) were evaluated. Under optimal conditions, the proposed method provided good enrichment factors in the range of 354–464, and good repeatability of the extractions (RSDs below 6.3%, n=5). The limits of detection were in the range of 0.2–5.0ngmL−1, depending on the analytes. The linearities were between 1 and 500ngmL−1 for BP, 5 and 500ngmL−1 for BP-3 and HMS and 10 and 500ngmL−1 for EHS. Finally, the proposed method was successfully applied to the determination of UV filters in river, swimming pool and tap water samples and acceptable relative recoveries over the range of 71.0–118.0% were obtained.
Keywords: Ionic liquid; Ultrasound-assisted dispersive liquid–liquid microextraction; Water samples; High-performance liquid chromatography; Benzophenone UV filters
Ionic liquid-based ultrasound-assisted dispersive liquid–liquid microextraction followed high-performance liquid chromatography for the determination of ultraviolet filters in environmental water samples by Yufeng Zhang; Hian Kee Lee (pp. 120-126).
Display Omitted► [HMIM][FAP] was for the first time employed as extraction solvent in USA-DLLME. ► [HMIM][FAP] showed high extraction efficiency for UV filters in water. ► The new method avoided the use of highly toxic chlorinated extraction solvents. ► Fast extraction time relative to other methods was another advantage. ► Simple and efficient method with low LODs, good repeatability and linearity.In the present study, a rapid, highly efficient and environmentally friendly sample preparation method named ionic liquid-based ultrasound-assisted dispersive liquid–liquid microextraction (IL-USA-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for the extraction and preconcentration of four benzophenone-type ultraviolet (UV) filters ( viz. benzophenone (BP), 2-hydroxy-4-methoxybenzophenone (BP-3), ethylhexyl salicylate (EHS) and homosalate (HMS)) from three different water matrices. The procedure was based on a ternary solvent system containing tiny droplets of ionic liquid (IL) in the sample solution formed by dissolving an appropriate amount of the IL extraction solvent 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM][FAP]) in a small amount of water-miscible dispersive solvent (methanol). An ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution, which markedly increased the extraction efficiency and reduced the equilibrium time. Various parameters that affected the extraction efficiency (such as type and volume of extraction and dispersive solvents, ionic strength, pH and extraction time) were evaluated. Under optimal conditions, the proposed method provided good enrichment factors in the range of 354–464, and good repeatability of the extractions (RSDs below 6.3%, n=5). The limits of detection were in the range of 0.2–5.0ngmL−1, depending on the analytes. The linearities were between 1 and 500ngmL−1 for BP, 5 and 500ngmL−1 for BP-3 and HMS and 10 and 500ngmL−1 for EHS. Finally, the proposed method was successfully applied to the determination of UV filters in river, swimming pool and tap water samples and acceptable relative recoveries over the range of 71.0–118.0% were obtained.
Keywords: Ionic liquid; Ultrasound-assisted dispersive liquid–liquid microextraction; Water samples; High-performance liquid chromatography; Benzophenone UV filters
Improved DNA extraction efficiency from low level cell numbers using a silica monolith based micro fluidic device by Loay Kashkary; Cordula Kemp; Kirsty J. Shaw; Gillian M. Greenway; Stephen J. Haswell (pp. 127-131).
Display Omitted► In situ fabrication of silica monoliths within micro fluidic devices. ► Improved DNA extraction efficiency from low cell numbers. ► Relevant to forensic or clinical diagnostics applications.The evaluation of a micro fluidic system with an integrated silica monolith for performing DNA extraction from limited biological samples has been carried out. Low DNA target concentrations usually require the addition of carrier RNA to ensure desired extraction efficiencies. Here, we demonstrate a micro fluidic extraction system with increasingly efficient extraction performances for biological samples containing <15ng of total DNA without the need of adding carrier nucleic acids. All extracted DNA showed successful amplification via the polymerase chain reaction demonstrating both the effectiveness of the proposed system at removing potential inhibitors and yielding good quality DNA. The work presented here beneficially identifies reduced sample volumes/concentrations as suitable for processing with respect to downstream analysis by enabling pre-concentration of the biological sample, particularly important when dealing with clinical or forensic specimens.
Keywords: Abbreviations; EDTA; ethylene diaminetetraacetic acid; EMEM; Eagle's minimum essential medium; GuHCl; guanidine hydrochloride; PCR; polymerase chain reaction; TBE; Tris–borate–EDTA buffer; TE; Tris–EDTA bufferDNA extraction; Monolith; Micro fluidic
Improved DNA extraction efficiency from low level cell numbers using a silica monolith based micro fluidic device by Loay Kashkary; Cordula Kemp; Kirsty J. Shaw; Gillian M. Greenway; Stephen J. Haswell (pp. 127-131).
Display Omitted► In situ fabrication of silica monoliths within micro fluidic devices. ► Improved DNA extraction efficiency from low cell numbers. ► Relevant to forensic or clinical diagnostics applications.The evaluation of a micro fluidic system with an integrated silica monolith for performing DNA extraction from limited biological samples has been carried out. Low DNA target concentrations usually require the addition of carrier RNA to ensure desired extraction efficiencies. Here, we demonstrate a micro fluidic extraction system with increasingly efficient extraction performances for biological samples containing <15ng of total DNA without the need of adding carrier nucleic acids. All extracted DNA showed successful amplification via the polymerase chain reaction demonstrating both the effectiveness of the proposed system at removing potential inhibitors and yielding good quality DNA. The work presented here beneficially identifies reduced sample volumes/concentrations as suitable for processing with respect to downstream analysis by enabling pre-concentration of the biological sample, particularly important when dealing with clinical or forensic specimens.
Keywords: Abbreviations; EDTA; ethylene diaminetetraacetic acid; EMEM; Eagle's minimum essential medium; GuHCl; guanidine hydrochloride; PCR; polymerase chain reaction; TBE; Tris–borate–EDTA buffer; TE; Tris–EDTA bufferDNA extraction; Monolith; Micro fluidic
SPME – Quo vadis? by Barbara Bojko; Erasmus Cudjoe; German A. Gómez-Ríos; Krzysztof Gorynski; Ruifen Jiang; Nathaly Reyes-Garcés; Sanja Risticevic; Érica A.S. Silva; Oluranti Togunde; Dajana Vuckovic; Janusz Pawliszyn (pp. 132-151).
Display Omitted► Recent developments in SPME relevant to future grown of its application are reviewed. ► Strategies to sample complex matrices are emphasized. ► Technologies facilitating on-site and in vivo sampling/sample preparation are described.Solid phase microextraction (SPME) has experienced rapid development and growth in number of application areas since its inception over 20 years ago. It has had a major impact on sampling and sample preparation practices in chemical analysis, bioanalysis, food and environmental sciences. A significant impact is expected in clinical analysis as well as pharmaceutical and medical sciences in the near future. In this review, recent developments of SPME and related technologies are discussed including an in-vial standard gas system for calibration of SPME in high throughput mode; a thin film geometry with high extraction efficiency SPME for gas chromatography (GC) and liquid chromatography (LC) analyses; and couplings of SPME with portable instruments permitting on-site measurements. Also, the latest advances in the preparation of sorbents applicable for direct extraction from complex biological matrices as well as applications of these extraction phases in food analysis and biomedical studies such as therapeutic drug monitoring and pharmacokinetics are described. Finally, recent trends in metabolomics analysis and examples of clinical monitoring of biomarkers with SPME are reviewed.
Keywords: Sampling; Sample preparation; SPME; In vivo; On-site; Solventless
SPME – Quo vadis? by Barbara Bojko; Erasmus Cudjoe; German A. Gómez-Ríos; Krzysztof Gorynski; Ruifen Jiang; Nathaly Reyes-Garcés; Sanja Risticevic; Érica A.S. Silva; Oluranti Togunde; Dajana Vuckovic; Janusz Pawliszyn (pp. 132-151).
Display Omitted► Recent developments in SPME relevant to future grown of its application are reviewed. ► Strategies to sample complex matrices are emphasized. ► Technologies facilitating on-site and in vivo sampling/sample preparation are described.Solid phase microextraction (SPME) has experienced rapid development and growth in number of application areas since its inception over 20 years ago. It has had a major impact on sampling and sample preparation practices in chemical analysis, bioanalysis, food and environmental sciences. A significant impact is expected in clinical analysis as well as pharmaceutical and medical sciences in the near future. In this review, recent developments of SPME and related technologies are discussed including an in-vial standard gas system for calibration of SPME in high throughput mode; a thin film geometry with high extraction efficiency SPME for gas chromatography (GC) and liquid chromatography (LC) analyses; and couplings of SPME with portable instruments permitting on-site measurements. Also, the latest advances in the preparation of sorbents applicable for direct extraction from complex biological matrices as well as applications of these extraction phases in food analysis and biomedical studies such as therapeutic drug monitoring and pharmacokinetics are described. Finally, recent trends in metabolomics analysis and examples of clinical monitoring of biomarkers with SPME are reviewed.
Keywords: Sampling; Sample preparation; SPME; In vivo; On-site; Solventless
Simultaneous analysis of 28 urinary VOC metabolites using ultra high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI/MSMS) by K. Udeni Alwis; Benjamin C. Blount; April S. Britt; Dhrusti Patel; David L. Ashley (pp. 152-160).
Display Omitted► We developed an UPLC-ESI/MSMS method to measure 28 urinary VOC metabolites. ► This high throughput method is precise, accurate and sensitive. ► Smokers had higher levels of urinary VOC metabolites compared to non-smokers. ► Serum cotinine correlated well with tobacco related VOC metabolites in urine. ► Urinary VOC metabolites are effective biomarkers of tobacco-related VOC exposure.Volatile organic compounds (VOCs) are ubiquitous in the environment, originating from many different natural and anthropogenic sources, including tobacco smoke. Long-term exposure to certain VOCs may increase the risk for cancer, birth defects, and neurocognitive impairment. Therefore, VOC exposure is an area of significant public health concern. Urinary VOC metabolites are useful biomarkers for assessing VOC exposure because of non-invasiveness of sampling and longer physiological half-lives of urinary metabolites compared with VOCs in blood and breath. We developed a method using reversed-phase ultra high performance liquid chromatography (UPLC) coupled with electrospray ionization tandem mass spectrometry (ESI/MSMS) to simultaneously quantify 28 urinary VOC metabolites as biomarkers of exposure. We describe a method that monitors metabolites of acrolein, acrylamide, acrylonitrile, benzene, 1-bromopropane, 1,3-butadiene, carbon-disulfide, crotonaldehyde, cyanide, N,N-dimethylformamide, ethylbenzene, ethylene oxide, propylene oxide, styrene, tetrachloroethylene, toluene, trichloroethylene, vinyl chloride and xylene. The method is accurate (mean accuracy for spiked matrix ranged from 84 to104%), sensitive (limit of detection ranged from 0.5 to 20ngmL−1) and precise (the relative standard deviations ranged from 2.5 to 11%). We applied this method to urine samples collected from 1203 non-smokers and 347 smokers and demonstrated that smokers have significantly elevated levels of tobacco-related biomarkers compared to non-smokers. We found significant ( p<0.0001) correlations between serum cotinine and most of the tobacco-related biomarkers measured. These findings confirm that this method can effectively quantify urinary VOC metabolites in a population exposed to volatile organics.
Keywords: VOC metabolites; Urinary biomarkers; Tobacco-related; UPLC-ESI/MSMS; Endogenous; Correlation
Simultaneous analysis of 28 urinary VOC metabolites using ultra high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI/MSMS) by K. Udeni Alwis; Benjamin C. Blount; April S. Britt; Dhrusti Patel; David L. Ashley (pp. 152-160).
Display Omitted► We developed an UPLC-ESI/MSMS method to measure 28 urinary VOC metabolites. ► This high throughput method is precise, accurate and sensitive. ► Smokers had higher levels of urinary VOC metabolites compared to non-smokers. ► Serum cotinine correlated well with tobacco related VOC metabolites in urine. ► Urinary VOC metabolites are effective biomarkers of tobacco-related VOC exposure.Volatile organic compounds (VOCs) are ubiquitous in the environment, originating from many different natural and anthropogenic sources, including tobacco smoke. Long-term exposure to certain VOCs may increase the risk for cancer, birth defects, and neurocognitive impairment. Therefore, VOC exposure is an area of significant public health concern. Urinary VOC metabolites are useful biomarkers for assessing VOC exposure because of non-invasiveness of sampling and longer physiological half-lives of urinary metabolites compared with VOCs in blood and breath. We developed a method using reversed-phase ultra high performance liquid chromatography (UPLC) coupled with electrospray ionization tandem mass spectrometry (ESI/MSMS) to simultaneously quantify 28 urinary VOC metabolites as biomarkers of exposure. We describe a method that monitors metabolites of acrolein, acrylamide, acrylonitrile, benzene, 1-bromopropane, 1,3-butadiene, carbon-disulfide, crotonaldehyde, cyanide, N,N-dimethylformamide, ethylbenzene, ethylene oxide, propylene oxide, styrene, tetrachloroethylene, toluene, trichloroethylene, vinyl chloride and xylene. The method is accurate (mean accuracy for spiked matrix ranged from 84 to104%), sensitive (limit of detection ranged from 0.5 to 20ngmL−1) and precise (the relative standard deviations ranged from 2.5 to 11%). We applied this method to urine samples collected from 1203 non-smokers and 347 smokers and demonstrated that smokers have significantly elevated levels of tobacco-related biomarkers compared to non-smokers. We found significant ( p<0.0001) correlations between serum cotinine and most of the tobacco-related biomarkers measured. These findings confirm that this method can effectively quantify urinary VOC metabolites in a population exposed to volatile organics.
Keywords: VOC metabolites; Urinary biomarkers; Tobacco-related; UPLC-ESI/MSMS; Endogenous; Correlation
Development of an isotope labeling ultra-high performance liquid chromatography mass spectrometric method for quantification of acylglycines in human urine by Avalyn Stanislaus; Kevin Guo; Liang Li (pp. 161-172).
Acylglycines play a crucial regulatory and detoxification role in the accumulation of the corresponding acyl CoA esters and are an important class of metabolites in the diagnoses of inborn errors of metabolism. Sensitive quantification of a large number of acylglycines not only improves diagnosis but also enables the discovery of potential new biomarkers of diseases. We report an ultra-high performance liquid chromatography tandem mass spectrometry (UPLC–MS) method for quantifying acylglycines in human urine with high sensitivity. This method is based on the use of a newly developed isotope labeling reagent, p-dimethylaminophenacyl (DmPA) bromide, to label acylglycines to improve detection sensitivity. Eighteen acylglycines, namely acetylglycine, propionylglycine, isobutyrylglycine, butyrylglycine, 4-hydroxyphenylacetylglycine, 2-furoylglycine, tiglylglycine, 2-methybutyrylglycine, 3-methylcrotonylglycine, isovalerylglycine, valerylglycine, hexanoylglycine, phenylacetylglycine, phenylpropionylglycine, glutarylglycine, heptanoylglycine, octanoylglycine and suberylglycine, were measured. This method uses calibration standards prepared in surrogate matrix (un-derivatized urine) and stable-isotope labeled analytes as the internal standards. The analysis was carried out in the positive ion detection mode using multiple reaction monitoring (MRM) survey scans. The calibration curves were validated over the range of 1.0–500nM. The method achieved a lower limit of quantitation (LLOQ) of 1–5nM for all analytes, as measured by the standard derivations associated with calibration curves and confirmed in surrogate matrix; the signal-to-noise ratio at LLOQ ranged from 12.50 to 156.70. Both accuracy (% RE or relative error) and precision (% CV) were <15%. Matrix effects were minimized using the surrogate matrix. All eighteen analytes were stable in urine for at least 5h at room temperature, autosampler (4°C) for 24h, 7 weeks at −20°C and after three freeze/thaw cycles. This surrogate matrix approach was validated using a standard addition experiment. As an example of applications, the endogenous concentrations of all eighteen analytes in urine samples of 20 healthy individuals collected in three consecutive days (i.e., 60 samples) were determined; there was no significant correlation found between the acylglycine profile and gender or body mass indices.
Keywords: Tandem mass spectrometry; Liquid chromatography; Isotope labeling; Acylglycines; Endogenous metabolites; Metabolomics
Development of an isotope labeling ultra-high performance liquid chromatography mass spectrometric method for quantification of acylglycines in human urine by Avalyn Stanislaus; Kevin Guo; Liang Li (pp. 161-172).
Acylglycines play a crucial regulatory and detoxification role in the accumulation of the corresponding acyl CoA esters and are an important class of metabolites in the diagnoses of inborn errors of metabolism. Sensitive quantification of a large number of acylglycines not only improves diagnosis but also enables the discovery of potential new biomarkers of diseases. We report an ultra-high performance liquid chromatography tandem mass spectrometry (UPLC–MS) method for quantifying acylglycines in human urine with high sensitivity. This method is based on the use of a newly developed isotope labeling reagent, p-dimethylaminophenacyl (DmPA) bromide, to label acylglycines to improve detection sensitivity. Eighteen acylglycines, namely acetylglycine, propionylglycine, isobutyrylglycine, butyrylglycine, 4-hydroxyphenylacetylglycine, 2-furoylglycine, tiglylglycine, 2-methybutyrylglycine, 3-methylcrotonylglycine, isovalerylglycine, valerylglycine, hexanoylglycine, phenylacetylglycine, phenylpropionylglycine, glutarylglycine, heptanoylglycine, octanoylglycine and suberylglycine, were measured. This method uses calibration standards prepared in surrogate matrix (un-derivatized urine) and stable-isotope labeled analytes as the internal standards. The analysis was carried out in the positive ion detection mode using multiple reaction monitoring (MRM) survey scans. The calibration curves were validated over the range of 1.0–500nM. The method achieved a lower limit of quantitation (LLOQ) of 1–5nM for all analytes, as measured by the standard derivations associated with calibration curves and confirmed in surrogate matrix; the signal-to-noise ratio at LLOQ ranged from 12.50 to 156.70. Both accuracy (% RE or relative error) and precision (% CV) were <15%. Matrix effects were minimized using the surrogate matrix. All eighteen analytes were stable in urine for at least 5h at room temperature, autosampler (4°C) for 24h, 7 weeks at −20°C and after three freeze/thaw cycles. This surrogate matrix approach was validated using a standard addition experiment. As an example of applications, the endogenous concentrations of all eighteen analytes in urine samples of 20 healthy individuals collected in three consecutive days (i.e., 60 samples) were determined; there was no significant correlation found between the acylglycine profile and gender or body mass indices.
Keywords: Tandem mass spectrometry; Liquid chromatography; Isotope labeling; Acylglycines; Endogenous metabolites; Metabolomics
Determination of biothiols by a novel on-line HPLC-DTNB assay with post-column detection by Mustafa Özyürek; Sefa Baki; Nilay Güngör; S. Esin Çelik; Kubilay Güçlü; Reşat Apak (pp. 173-181).
Display Omitted► A new, rapid and sensitive on-line HPLC assay for biothiols was proposed. ► Postcolumn derivatization was performed with methyl-β-cyclodextrin-containing DTNB. ► Biothiols were selectively determined individually among other antioxidants. ► The oligosaccharide helped to improve the sensitivity.A novel on-line HPLC-DTNB method was developed for the selective determination of biologically important thiols (biothiols) such asl-cysteine (Cys), glutathione (GSH), homocysteine (HCys), N-acetylcysteine (NAC), and 1,4-dithioerythritol (DTE) in pharmaceuticals and tissue homogenates. The biothiols were separated on C18 column using gradient elution, reacted with the postcolumn reagent, DTNB in 0.5% M-β-CD (w/v) solution at pH 8, to form yellow-colored 5-thio-2-nitrobenzoic acid (TNB), and monitored with a PDA detector ( λ=410nm). With the optimized conditions for chromatography and the post-column derivatization, 40nM of NAC, 40nM of Cys, and 50nM of GSH can be determined. The relative standard deviations of the recommended method were in the range of 3.2–5.4% for 50μM biothiols. The negative peaks of biothiol constituents were monitored by measuring the increase in absorbance due to TNB chromophore. The detection limits of biothiols at 410nm (in the range of 0.04–0.58μM) after post-column derivatization with DTNB+M-β-CD were much lower than those at 205nm UV-detection without derivatization, and were distinctly lower than those with post-column DTNB alone. The method is rapid, inexpensive, versatile, nonlaborious, uses stable reagents, and enables the on-line qualitative and quantitative estimation of biothiol constituents of biological fluids and pharmaceuticals.
Keywords: On-line HPLC-DTNB; Post-column detection; Spectrophotometric DTNB assay; Biothiols
Determination of biothiols by a novel on-line HPLC-DTNB assay with post-column detection by Mustafa Özyürek; Sefa Baki; Nilay Güngör; S. Esin Çelik; Kubilay Güçlü; Reşat Apak (pp. 173-181).
Display Omitted► A new, rapid and sensitive on-line HPLC assay for biothiols was proposed. ► Postcolumn derivatization was performed with methyl-β-cyclodextrin-containing DTNB. ► Biothiols were selectively determined individually among other antioxidants. ► The oligosaccharide helped to improve the sensitivity.A novel on-line HPLC-DTNB method was developed for the selective determination of biologically important thiols (biothiols) such asl-cysteine (Cys), glutathione (GSH), homocysteine (HCys), N-acetylcysteine (NAC), and 1,4-dithioerythritol (DTE) in pharmaceuticals and tissue homogenates. The biothiols were separated on C18 column using gradient elution, reacted with the postcolumn reagent, DTNB in 0.5% M-β-CD (w/v) solution at pH 8, to form yellow-colored 5-thio-2-nitrobenzoic acid (TNB), and monitored with a PDA detector ( λ=410nm). With the optimized conditions for chromatography and the post-column derivatization, 40nM of NAC, 40nM of Cys, and 50nM of GSH can be determined. The relative standard deviations of the recommended method were in the range of 3.2–5.4% for 50μM biothiols. The negative peaks of biothiol constituents were monitored by measuring the increase in absorbance due to TNB chromophore. The detection limits of biothiols at 410nm (in the range of 0.04–0.58μM) after post-column derivatization with DTNB+M-β-CD were much lower than those at 205nm UV-detection without derivatization, and were distinctly lower than those with post-column DTNB alone. The method is rapid, inexpensive, versatile, nonlaborious, uses stable reagents, and enables the on-line qualitative and quantitative estimation of biothiol constituents of biological fluids and pharmaceuticals.
Keywords: On-line HPLC-DTNB; Post-column detection; Spectrophotometric DTNB assay; Biothiols
A fluorescent molecular switch for room temperature operation based on oligonucleotide hybridization without labeling of probes or targets by Melissa Massey; Ulrich J. Krull (pp. 182-190).
Display Omitted► A molecular switch triggered by oligonucleotide hybridization is evaluated. ► Chaotrope suppresses undesired electrostatic binding of intercalating dye. ► Chaotrope concurrently allows single base mismatch discrimination. ► Operation at room temperature and in solid-phase assay is reported.A molecular switch was prepared by self-assembly. Neutravidin served as a template that allowed for a biotinylated probe oligonucleotide to be placed adjacent to a biotinylated long-chain linker that was terminated with thiazole orange (TO). Hybridization of probe oligonucleotide with target to form double-stranded DNA resulted in intercalation of the adjacent TO probe. This was a reversible process that could be tracked by fluorescence intensity changes. Formamide was used as a denaturant for double-stranded DNA, and could be used to depress thermal denaturation temperatures. In this work formamide had a dual function, providing for control of hybridization selectivity at room temperature, while concurrently ameliorating non-specific adsorption to improve signal-to-noise when using thiazole orange as a fluorescence signalling agent to determine oligonucleotide hybridization. Room temperature single nucleotide polymorphism (SNP) discrimination for oligonucleotide targets was achieved both in solution and for molecular switches that were immobilized onto optical fibers. In solution, a concentration of 18.5% formamide provided greater than 40-fold signal difference between single-stranded DNA and double-stranded DNA, in contrast to only a 2-fold difference in the absence of formamide. Selectivity for SNP determination in solution was demonstrated using targets of varying lengths including a 141-base PCR amplicon. The improved signal-to-noise achieved by use of formamide is likely due to preferential displacement of dye molecules that are otherwise electrostatically bound to the polyanionic nucleic acid backbone.
Keywords: Fluorescence; Thiazole orange; Molecular switch; Single nucleotide polymorphism; Amplicon; Formamide
A fluorescent molecular switch for room temperature operation based on oligonucleotide hybridization without labeling of probes or targets by Melissa Massey; Ulrich J. Krull (pp. 182-190).
Display Omitted► A molecular switch triggered by oligonucleotide hybridization is evaluated. ► Chaotrope suppresses undesired electrostatic binding of intercalating dye. ► Chaotrope concurrently allows single base mismatch discrimination. ► Operation at room temperature and in solid-phase assay is reported.A molecular switch was prepared by self-assembly. Neutravidin served as a template that allowed for a biotinylated probe oligonucleotide to be placed adjacent to a biotinylated long-chain linker that was terminated with thiazole orange (TO). Hybridization of probe oligonucleotide with target to form double-stranded DNA resulted in intercalation of the adjacent TO probe. This was a reversible process that could be tracked by fluorescence intensity changes. Formamide was used as a denaturant for double-stranded DNA, and could be used to depress thermal denaturation temperatures. In this work formamide had a dual function, providing for control of hybridization selectivity at room temperature, while concurrently ameliorating non-specific adsorption to improve signal-to-noise when using thiazole orange as a fluorescence signalling agent to determine oligonucleotide hybridization. Room temperature single nucleotide polymorphism (SNP) discrimination for oligonucleotide targets was achieved both in solution and for molecular switches that were immobilized onto optical fibers. In solution, a concentration of 18.5% formamide provided greater than 40-fold signal difference between single-stranded DNA and double-stranded DNA, in contrast to only a 2-fold difference in the absence of formamide. Selectivity for SNP determination in solution was demonstrated using targets of varying lengths including a 141-base PCR amplicon. The improved signal-to-noise achieved by use of formamide is likely due to preferential displacement of dye molecules that are otherwise electrostatically bound to the polyanionic nucleic acid backbone.
Keywords: Fluorescence; Thiazole orange; Molecular switch; Single nucleotide polymorphism; Amplicon; Formamide
Multiplex competitive microbead-based flow cytometric immunoassay using quantum dot fluorescent labels by Hye-Weon Yu; In S. Kim; Reinhard Niessner; Dietmar Knopp (pp. 191-198).
Display Omitted► First time, duplex competitive bead-based flow cytometric immunoassay was developed using ODs. ► Antibody-coated QD detection probes and antigen-immobilized microspheres were synthesized. ► The two model target analytes were low molecular weight compounds of microbial and chemical origin. ► The determination of different water types was possible after simple filtration of samples.In answer to the ever-increasing need to perform the simultaneous analysis of environmental hazards, microcarrier-based multiplex technologies show great promise. Further integration with biofunctionalized quantum dots (QDs) creates new opportunities to extend the capabilities of multicolor flow cytometry with their unique fluorescence properties. Here, we have developed a competitive microbead-based flow cytometric immunoassay using QDs fluorescent labels for simultaneous detection of two analytes, bringing the benefits of sensitive, rapid and easy-of-manipulation analytical tool for environmental contaminants. As model target compounds, the cyanobacterial toxin microcystin-LR and the polycyclic aromatic hydrocarbon compound benzo[a]pyrene were selected. The assay was carried out in two steps: the competitive immunological reaction of multiple targets using their exclusive sensing elements of QD/antibody detection probes and antigen-coated microsphere, and the subsequent flow cytometric analysis. The fluorescence of the QD-encoded microsphere was thus found to be inversely proportional to target analyte concentration. Under optimized conditions, the proposed assay performed well within 30min for the identification and quantitative analysis of the two environmental contaminants. For microcystin-LR and benzo[a]pyrene, dose–response curves with IC50 values of 5μgL−1 and 1.1μgL−1 and dynamic ranges of 0.52–30μgL−1 and 0.13–10μgL−1 were obtained, respectively. Recovery was 92.6–106.5% for 5 types of water samples like bottled water, tap water, surface water and seawater using only filtration as sample pretreatment.
Keywords: Quantum dot; Flow cytometry; Competitive immunoassay; Multiplexing; Benzo[a]pyrene; Microcystin-LR
Multiplex competitive microbead-based flow cytometric immunoassay using quantum dot fluorescent labels by Hye-Weon Yu; In S. Kim; Reinhard Niessner; Dietmar Knopp (pp. 191-198).
Display Omitted► First time, duplex competitive bead-based flow cytometric immunoassay was developed using ODs. ► Antibody-coated QD detection probes and antigen-immobilized microspheres were synthesized. ► The two model target analytes were low molecular weight compounds of microbial and chemical origin. ► The determination of different water types was possible after simple filtration of samples.In answer to the ever-increasing need to perform the simultaneous analysis of environmental hazards, microcarrier-based multiplex technologies show great promise. Further integration with biofunctionalized quantum dots (QDs) creates new opportunities to extend the capabilities of multicolor flow cytometry with their unique fluorescence properties. Here, we have developed a competitive microbead-based flow cytometric immunoassay using QDs fluorescent labels for simultaneous detection of two analytes, bringing the benefits of sensitive, rapid and easy-of-manipulation analytical tool for environmental contaminants. As model target compounds, the cyanobacterial toxin microcystin-LR and the polycyclic aromatic hydrocarbon compound benzo[a]pyrene were selected. The assay was carried out in two steps: the competitive immunological reaction of multiple targets using their exclusive sensing elements of QD/antibody detection probes and antigen-coated microsphere, and the subsequent flow cytometric analysis. The fluorescence of the QD-encoded microsphere was thus found to be inversely proportional to target analyte concentration. Under optimized conditions, the proposed assay performed well within 30min for the identification and quantitative analysis of the two environmental contaminants. For microcystin-LR and benzo[a]pyrene, dose–response curves with IC50 values of 5μgL−1 and 1.1μgL−1 and dynamic ranges of 0.52–30μgL−1 and 0.13–10μgL−1 were obtained, respectively. Recovery was 92.6–106.5% for 5 types of water samples like bottled water, tap water, surface water and seawater using only filtration as sample pretreatment.
Keywords: Quantum dot; Flow cytometry; Competitive immunoassay; Multiplexing; Benzo[a]pyrene; Microcystin-LR
Investigation of polar organic solvents compatible with Corona Charged Aerosol Detection and their use for the determination of sugars by hydrophilic interaction liquid chromatography by Joseph P. Hutchinson; Tomas Remenyi; Pavel Nesterenko; William Farrell; Elizabeth Groeber; Roman Szucs; Greg Dicinoski; Paul R. Haddad (pp. 199-206).
Response plot for the Corona Charged Aerosol Detector using different amounts of acetone in the mobile phase and different concentrations of a non-volatile test analyte.Display Omitted► Alternative, green solvents to acetonitrile were investigated with a Corona CAD. ► 3D models were formed relating analyte concentration, mobile phase composition and response. ► The separation performance of alternative solvents was compared using HILIC. ► Similar analytical performance could be attained with alternative solvents such as acetone. ► Combines benefits of green separation methods with universal detection techniques.A range of organic solvents (ethanol, isopropanol and acetone) has been investigated as alternatives to acetonitrile and methanol when used in conjunction with Corona Charged Aerosol Detection (Corona CAD). These solvents have been evaluated with regard to their effect on the response of the Corona CAD. Three dimensional response surfaces were constructed using raw data showing the relationship between detector response, analyte concentration and percentage of organic solvent in the mobile phase, using sucralose or quinine as the test analyte. The detector response was non-linear in terms of analyte concentration for all solvents tested. However, detector response varied in an approximately linear manner with percentage of organic solvent over the range 0–40% for ethanol or isopropanol and 0–80% for acetone and methanol. The chromatographic performance of the various solvents when used as aqueous–organic mobile phases was evaluated for isocratic and gradient separations of sugars and sugar alcohols by hydrophilic interaction liquid chromatography (HILIC) using an Asahipak NH2P-504E column coupled with Corona CAD detection. It was found that whilst acetonitrile provided the highest column efficiencies and lowest detection limits of the solvents studied, acetone also performed well and could be used to resolve the same number of analytes as was possible with acetonitrile. Typical efficiencies and detection limits of 5330platesm−1 and 1.25μgmL−1, respectively, were achieved when acetone was used as the organic modifier. Acetone was utilised successfully as an organic modifier in the HILIC separation of carbohydrates in a beer sample and also for a partially digested dextran sample.
Keywords: Charged aerosol detector; Hydrophilic interaction chromatography; Carbohydrates; Green chemistry
Investigation of polar organic solvents compatible with Corona Charged Aerosol Detection and their use for the determination of sugars by hydrophilic interaction liquid chromatography by Joseph P. Hutchinson; Tomas Remenyi; Pavel Nesterenko; William Farrell; Elizabeth Groeber; Roman Szucs; Greg Dicinoski; Paul R. Haddad (pp. 199-206).
Response plot for the Corona Charged Aerosol Detector using different amounts of acetone in the mobile phase and different concentrations of a non-volatile test analyte.Display Omitted► Alternative, green solvents to acetonitrile were investigated with a Corona CAD. ► 3D models were formed relating analyte concentration, mobile phase composition and response. ► The separation performance of alternative solvents was compared using HILIC. ► Similar analytical performance could be attained with alternative solvents such as acetone. ► Combines benefits of green separation methods with universal detection techniques.A range of organic solvents (ethanol, isopropanol and acetone) has been investigated as alternatives to acetonitrile and methanol when used in conjunction with Corona Charged Aerosol Detection (Corona CAD). These solvents have been evaluated with regard to their effect on the response of the Corona CAD. Three dimensional response surfaces were constructed using raw data showing the relationship between detector response, analyte concentration and percentage of organic solvent in the mobile phase, using sucralose or quinine as the test analyte. The detector response was non-linear in terms of analyte concentration for all solvents tested. However, detector response varied in an approximately linear manner with percentage of organic solvent over the range 0–40% for ethanol or isopropanol and 0–80% for acetone and methanol. The chromatographic performance of the various solvents when used as aqueous–organic mobile phases was evaluated for isocratic and gradient separations of sugars and sugar alcohols by hydrophilic interaction liquid chromatography (HILIC) using an Asahipak NH2P-504E column coupled with Corona CAD detection. It was found that whilst acetonitrile provided the highest column efficiencies and lowest detection limits of the solvents studied, acetone also performed well and could be used to resolve the same number of analytes as was possible with acetonitrile. Typical efficiencies and detection limits of 5330platesm−1 and 1.25μgmL−1, respectively, were achieved when acetone was used as the organic modifier. Acetone was utilised successfully as an organic modifier in the HILIC separation of carbohydrates in a beer sample and also for a partially digested dextran sample.
Keywords: Charged aerosol detector; Hydrophilic interaction chromatography; Carbohydrates; Green chemistry
On-line amino acid-based capillary isoelectric focusing-ESI-MS/MS for protein digests analysis by Guijie Zhu; Liangliang Sun; Ping Yang; Norman J. Dovichi (pp. 207-211).
Display Omitted► Amino acids are used as ampholytes. ► Dramatic decrease in interfering background signal compared to commercial ampholytes. ► Improved detection limits.Six amino acids with pIs that ranged from 3.2 to 9.7 were used as ampholytes to establish a pH gradient in capillary isoelectric focusing. This amino acid-based capillary isoelectric focusing (cIEF) was coupled with ESI-MS/MS using an electrokinetically pumped sheath-flow interface for peptide analysis. Amino acid-based isoelectric focusing generates a two-order of magnitude lower background signal than commercial ampholytes in the important m/ z range of 300–1800. Good focusing was achieved for insulin receptor, which produced ∼10s peak width. For 0.1mgmL−1 bovine serum albumin (BSA) digests, 24±1 peptides (sequence coverage 47±4%) were identified in triplicate analysis. As expected, the BSA peptides were separated according to their pI. The concentration detection limit for the BSA digests is 7nM and the mass detection limit is 7fmole. A solution of six bovine protein tryptic digests spanning 5 orders of magnitude in concentration was analyzed by amino acid based cIEF-ESI-MS/MS. Five proteins with a concentration range spanning 4 orders of magnitude were identified in triplicate runs. Using amino acid based cIEF-ESI-MS/MS, 112 protein groups and 303 unique peptides were identified in triplicate runs of a RAW 264.7 cell homogenate protein digest. In comparison with ampholyte based cIEF-ESI-MS/MS, amino acid based cIEF-ESI-MS/MS produces higher resolution of five acidic peptides, much cleaner mass spectra, and higher protein spectral counts.
Keywords: Capillary isoelectric focusing; Electrospray; Mass spectrometry; Protein analysis
On-line amino acid-based capillary isoelectric focusing-ESI-MS/MS for protein digests analysis by Guijie Zhu; Liangliang Sun; Ping Yang; Norman J. Dovichi (pp. 207-211).
Display Omitted► Amino acids are used as ampholytes. ► Dramatic decrease in interfering background signal compared to commercial ampholytes. ► Improved detection limits.Six amino acids with pIs that ranged from 3.2 to 9.7 were used as ampholytes to establish a pH gradient in capillary isoelectric focusing. This amino acid-based capillary isoelectric focusing (cIEF) was coupled with ESI-MS/MS using an electrokinetically pumped sheath-flow interface for peptide analysis. Amino acid-based isoelectric focusing generates a two-order of magnitude lower background signal than commercial ampholytes in the important m/ z range of 300–1800. Good focusing was achieved for insulin receptor, which produced ∼10s peak width. For 0.1mgmL−1 bovine serum albumin (BSA) digests, 24±1 peptides (sequence coverage 47±4%) were identified in triplicate analysis. As expected, the BSA peptides were separated according to their pI. The concentration detection limit for the BSA digests is 7nM and the mass detection limit is 7fmole. A solution of six bovine protein tryptic digests spanning 5 orders of magnitude in concentration was analyzed by amino acid based cIEF-ESI-MS/MS. Five proteins with a concentration range spanning 4 orders of magnitude were identified in triplicate runs. Using amino acid based cIEF-ESI-MS/MS, 112 protein groups and 303 unique peptides were identified in triplicate runs of a RAW 264.7 cell homogenate protein digest. In comparison with ampholyte based cIEF-ESI-MS/MS, amino acid based cIEF-ESI-MS/MS produces higher resolution of five acidic peptides, much cleaner mass spectra, and higher protein spectral counts.
Keywords: Capillary isoelectric focusing; Electrospray; Mass spectrometry; Protein analysis