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Analytica Chimica Acta (v.774, #)
High-performance liquid chromatographic determination of histamine in biological samples: The cerebrospinal fluid challenge – A review by Zhaopin Wang; Juanli Wu; Shihua Wu; Aimin Bao (pp. 1-10).
Display Omitted► Detection of histamine in the cerebrospinal fluid (CSF) is of clinical importance. ► HPLC for CSF-histamine measurement is a challenging task due to the low levels. ► There is solution for improvement of HPLC for CSF-histamine level measurement. ► It is important for simultaneous measurement of histamine and its metabolites.Histamine, a neurotransmitter crucially involved in a number of basic physiological functions, undergoes changes in neuropsychiatric disorders. Detection of histamine in biological samples such as cerebrospinal fluid (CSF) is thus of clinical importance. The most commonly used method for measuring histamine levels is high performance liquid chromatography (HPLC). However, factors such as very low levels of histamine, the even lower CSF-histamine and CSF-histamine metabolite levels, especially in certain neuropsychiatric diseases, rapid formation of histamine metabolites, and other confounding elements during sample collection, make analysis of CSF-histamine and CSF-histamine metabolites a challenging task. Nonetheless, this challenge can be met, not only with respect to HPLC separation column, derivative reagent, and detector, but also in terms of optimizing the CSF sample collection. This review aims to provide a general insight into the quantitative analyses of histamine in biological samples, with an emphasis on HPLC instruments, methods, and hyphenated techniques, with the aim of promoting the development of an optimal and practical protocol for the determination of CSF-histamine and/or CSF-histamine metabolites.
Keywords: High-performance liquid chromatography; Cerebrospinal fluid; Histamine; Tele-methylhistamine; Tele-methylimidazoleacetic acid
Recent developments in assessment of bio-accessible trace metal fractions in airborne particulate matter: A review by Azam Mukhtar; Andreas Limbeck (pp. 11-25).
Display Omitted► Survey of leaching agents used for sample extraction. ► Multi-step fractionation schemes. ► Dynamic extraction procedures. ► Analytical approaches for element specific measurement. ► Detailed compilation of published results.In the last years a great deal of research has been focused on the determination of harmful trace metals such as Cd, Co, Cr, Cu, Ni or Pb in airborne particulate matter (APM). However, the commonly applied determination of total element concentrations in APM provides only an upper-end estimate of potential metal toxicity. For improved risk assessment it is important to determine bio-accessible concentrations instead of total metal contents. The present review gives an overview of analytical procedures reported for measurement of bio-accessible trace metal fractions in APM. The different approaches developed for extraction of soluble trace metals in APM are summarized. Furthermore the analytical techniques applied for accurate determination of dissolved trace metals in the presence of complex sample matrix are presented. Finally a compilation of published results for bio-accessible trace metals in APM is included.
Keywords: Airborne particulate matter; Bio-accessible trace metals; Elemental analysis; Fractionation schemes; Dynamic extraction procedures
Quantitative analysis of morphine in dried blood spots by using morphine-d3 pre-impregnated dried blood spot cards by John Mommers; Ynze Mengerink; Erik Ritzen; Jos Weusten; Jac van der Heijden; Sjoerd van der Wal (pp. 26-32).
Display Omitted•Pre-impregnation by immersing the DBS card in an IS-solution was investigated.•We demonstrated equal results when using IS impregnated or non-impregnated cards.•We demonstrated that the impregnated IS homogeneity is acceptable (CV 5%).•We demonstrated that the IS homogeneity is not disturbed by blood spotting.Two different internal standard dried blood spot (DBS) pre-impregnation procedures (prior to blood spotting) were investigated. In the first procedure DBS pre-impregnation is performed by immersing the DBS card fully into an internal standard solution. In the second procedure pre-impregnation is performed by pipetting a certain volume of an internal standard solution onto the DBS card. Morphine-d3 was used as the model compound for all experiments. The pre-impregnation procedure by immersing was further investigated with respect to homogeneity of impregnation, influence of different blood spotting techniques and the influence of spotting different blood volumes on the internal standard distribution, calibration and stability of pre-impregnated cards. Finally, the immersing procedure was used for the analysis of morphine in dried blood spots and the results were compared to the conventional procedure in which the internal standard morphine-d3 was added to the extraction solvent. The new pre-impregnated cards couple simplicity of operation and convenient use in the field to results equivalent to the conventional procedure.
Keywords: Dried blood spot; Dried matrix spot; Pre-impregnation; Deuterated internal standard; Quantification; Morphine; Morphine-d3
Distribution of pesticides in n-hexane/water and n-hexane/acetonitrile systems and estimation of possibilities of their extraction isolation and preconcentration from various matrices by M.F. Zayats; S.M. Leschev; N.V. Petrashkevich; M.A. Zayats; L. Kadenczki; R. Szitás; H. Szemán Dobrik; N. Keresztény (pp. 33-43).
Display Omitted•The extraction of 150 pesticides in different systems has been investigated.•The highest and most scattered values of Lg P are observed in hexane/water system.•The minimal and leveled values of Lg P are observed in hexane/acetonitrile system.•Conditions of pesticides separation and recovery are estimated on the basis of Lg P.Distribution of 150 most widely used pesticides of different chemical classes (amides, anilinopirimidines, aromatics, benzenesulfonates, carbamates, dicarboximides, organophosphorus compounds, phenyl esters, phenylureas, pyrazoles, pyrethroids, pyrimidines, strobilurins, sulfamides, triazines, triazoles, etc.) in n-hexane/water and n-hexane/acetonitrile systems was investigated at 25°C. Distribution constants of pesticides ( P) have been calculated as ratio of pesticide concentration in n-hexane to its concentration in water or acetonitrile phase. HPLC and GC methods were used for pesticides determination in phases. It was found that the overwhelming majority of pesticides are hydrophobic, i.e. in n-hexane/water system Lg P≫0, and the difference in Lg P values can reach 9.1 units. Replacement of water for acetonitrile leads to dramatic fall of Lg P values reaching 9.5 units. The majority of Lg P values in this case are negative and their differences is strongly leveled in comparison with a hexane/water system. Thus, maximal difference in pesticides Lg P values for n-hexane/acetonitrile system is 3.2 units. It is shown that n-hexane can be used for selective and efficient extraction and preconcentration of pesticides from water matrices. On the other hand, acetonitrile is effective for the isolation and preconcentration of pesticides from hydrocarbon and vegetable oil matrices. The distribution constants described in the paper may be effectively used for the estimation of possibilities of extraction isolation, preconcentration and separation of pesticides.
Keywords: Extraction; Distribution; Constant; Pesticide; Recovery; Acetonitrile; Hexane; Separation; Preconcentration; Sample preparation
One-step synthesis of agarose coated magnetic nanoparticles and their application in the solid phase extraction of Pd(II) using a new magnetic field agitation device by Mehdi Safdarian; Payman Hashemi; Mohsen Adeli (pp. 44-50).
The steps of the proposed MSPE-MFA method for the preconcentration of Pd(II).•A new one-step method was proposed for the preparation of agarose coated magnetic nanoparticles (ACMNPs).•A new magnetic field agitation device was designed for direct stirring of the magnetic particles in the solution.•The ACMNPs were functionalized by iminodiacetic acid and successfully applied to the preconcentration of Pd(II) in natural waters.A magnetic solid phase extraction method based on agarose coated magnetic nanoparticles)ACMNPs(coupled to a new magnetic field agitation (MFA) device was developed and investigated for the separation, preconcentration and determination of Pd(II) in aqueous solutions. For the first time, the formation of the nanoparticles and their encapsulation in agarose micro-flakes was conducted in a single step. For this purpose, preparation of the magnetic iron oxide nanoparticles was performed in an alkaline agarose solution. The sizes of Fe3O4 nanoparticles and agarose micro-flakes were 10–14nm and 90–130μm, respectively. The nanomagnetic agarose particles were functionalized by iminodiacetic acid and subjected to magnetic field agitation in the MFA device. The influence of different analytical parameters such as pH, ionic strength, type and volume of desorption solvent and amount of the adsorbent on the preconcentration of Pd(II) were investigated. Eight replicated analysis at the optimized conditions, resulted in a recovery of 94.1% with an RSD of 5.2% for Pd(II). The detection limit of the method (3 σ) was 47ngL−1 for the analyte. The method was successfully applied to the determination of Pd(II) in natural water samples.
Keywords: Agarose coated magnetic nanoparticles; Magnetic field agitation; Magnetic solid phase extraction; Palladium determination; Electrothermal atomic absorption spectrometry
Novel coatings for stir bar sorptive extraction to determine pharmaceuticals and personal care products in environmental waters by liquid chromatography and tandem mass spectrometry by Núria Gilart; Núria Miralles; Rosa Maria Marcé; Francesc Borrull; Núria Fontanals (pp. 51-60).
•Three commercial coatings for SBSE to extract PPCPs in wastewaters were tested.•EG Silicone coating provided better recoveries than PA and PDMS ones for PPCPs.•SBSE (EG Silicone Twister®)/LC–MS/MS method was validated with low detection limits.•A group of pharmaceuticals and personal care products were detected in wastewaters.Two new commercially available polar coatings for stir bar sorptive extraction (SBSE), consisting of polyacrylate (PA) with a proportion of polyethyleneglycol (PEG) (Acrylate Twister®) and PEG modified silicone (EG Silicone Twister®), were evaluated and compared with the classic coating based on polydimethylsiloxane (PDMS Twister®) for the extraction of a group of pharmaceuticals and personal care products (PPCPs) from wastewater samples.The SBSE parameters, such as sample pH, agitation speed, extraction temperature, extraction time, desorption solvent and time, were optimised in order to achieve suitable sorption of the target analytes. The EG Silicone coating enabled more efficient extraction of some polar compounds as well as improving the sorption of apolar compounds, in comparison with the other two coatings.Finally, the method of SBSE followed by liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) using the EG Silicone coating was validated achieving good linearity ( r2>0.994, except for CBZ ( r2>0.989)), precision (%RSD<17%) and low limits of quantification (LOQs) (20–40ngL−1). The SBSE/LC–MS/MS methodology was applied for the determination of PPCPs in wastewater samples.
Keywords: Commercial polar coatings; Stir bar sorptive extraction; Tandem mass spectrometry; Pharmaceuticals and personal care products; Wastewaters
Quantitative analysis of differentially expressed saliva proteins in human immunodeficiency virus type 1 (HIV-1) infected individuals by Nawei Zhang; Zhenyu Zhang; Shan Feng; Qingtao Wang; Daniel Malamud; Haiteng Deng (pp. 61-66).
Display Omitted► A high-throughput method for profiling and quantification of the differentially expressed proteins in saliva samples was developed. ► Identified that DMBT1, S100A7, S100A8, S100A9 and alpha defensin were up-regulated in saliva from HIV-1 seropositive patients. ► Established analytical strategies are translatable to the clinical setting.In the present study, we have established a new methodology to analyze saliva proteins from HIV-1-seropositive patients before highly active antiretroviral therapy (HAART) and seronegative controls. A total of 593 and 601 proteins were identified in the pooled saliva samples from 5 HIV-1 subjects and 5 controls, respectively. Forty-one proteins were found to be differentially expressed. Bioinformatic analysis of differentially expressed salivary proteins showed an increase of antimicrobial proteins and decrease of protease inhibitors upon HIV-1 infection. To validate some of these differentially expressed proteins, a high-throughput quantitation method was established to determine concentrations of 10 salivary proteins in 40 individual saliva samples from 20 seropositive patients before HAART and 20 seronegative subjects. This method was based on limited protein separation within the zone of the stacking gel of the 1D SDS PAGE and using isotope-coded synthetic peptides as internal standards. The results demonstrated that a combination of protein profiling and targeted quantitation is an efficient method to identify and validate differentially expressed salivary proteins. Expression levels of members of the calcium-binding S100 protein family and deleted in malignant brain tumors 1 protein (DMBT1) were up-regulated while that of Mucin 5B was down-regulated in HIV-1 seropositive saliva samples, which may provide new perspectives for monitoring HIV-infection and understanding the mechanism of HIV-1 infectivity.
Keywords: HIV-1; Saliva; Quantitation; Limited separation; Proteomics
Fibrinolysis and thrombosis of fibrinogen-modified gold nanoparticles for detection of fibrinolytic-related proteins by Jyun-Wei Jian; Wei-Chane Chiu; Huan-Tsung Chang; Pang-Hung Hsu; Chih-Ching Huang (pp. 67-72).
Display Omitted► We developed two simple assays for plasmin, plasminogen, urokinase, and α2-plasmin. ► The sensors used fibrinogen-modified gold nanoparticles. ► Plasmin activity was determined in a biological medium mimic solution. ► Plasmin and plasminogen were determined in serum using a thrombin-modified sensor.Fibrinolysis (plasmin-mediated cleavage of fibrin structures) is a process in which fibrin clots can be removed from blood vessels, allowing the return of normal vascular function. Although several methods have been developed to measure plasmin activity and plasminogen (the plasmin precursor) concentrations, they are only moderately sensitive and quantitative and require large amounts of reagents, limiting their applicability. We developed two simple, label-free homogeneous assays using gold nanoparticles (Au NPs) for detection of fibrinolysis-related proteins and their activator (urokinase that converts plasminogen to plasmin) and inhibitor (α2-plasmin inhibitor that inhibits plasmin and plasminogen bound to fibrin). We used a fibrinolysis-based sensor, based on plasmin-mediated cleavage of fibrinogen-modified Au NPs (Fib-Au NPs) leading to aggregation of Au NPs, to determine plasmin activity in a biological medium mimic solution. A combination of thrombin (Thr) and Fib-Au NPs allowed us to analyze plasmin activity and plasminogen concentrations in serum through Thr-induced agglutination of Fib-Au NPs. The limit of detection (LOD; S/N=3) of this sensor for plasmin in serum was 0.4nM (ca. 1.7×10−4unitmL−1). These label-free assays offer several advantages over conventional assays, including allowing rapid and simple readings with the naked eye or measurement by UV–vis absorption spectroscopy.
Keywords: Gold nanoparticles; Label-free assays; Fibrinolysis; Plasminogen; Thrombin; Serum samples
Miniaturized electrochemical system for cholinesterase inhibitor detection by Anthony J. Veloso; Paul M. Nagy; Biao Zhang; Devjani Dhar; Anqi Liang; Tarek Ibrahim; Svetlana Mikhaylichenko; Isabelle Aubert; Kagan Kerman (pp. 73-78).
Display Omitted► Acetylcholinesterase inhibitor activity was measured on label-free electrodes. ► Electrochemical detection was validated against Ellman's colorimetric assay. ► FDA approved acetylcholinesterase inhibitor was implemented as a positive control. ► The IC50 values determined for Donepezil were comparable between assays. ► IC50 were determined using cholinesterases extracted homogenates of C57BL/6J mice.The utility of a simple, low-cost detection platform for label-free electrochemical characterization of acetylcholinesterase (AChE) inhibition is demonstrated as a potential tool for screening of small-molecule therapeutic agents for Alzheimer's disease (AD). Technique validation was performed against the standard Ellman's colorimetric assay using the clinically established cholinesterase inhibitor (ChEI), Donepezil (Aricept®). Electrochemical measurements were obtained by differential pulse voltammetry (DPV) performed using a portable potentiostat system for detection of the enzymatic product, thiocholine (TCh), by direct oxidation on unmodified gold screen-printed electrodes. The IC50 profiles for Donepezil measured in vitro were found to be comparable between both colorimetric and electrochemical detection methods for the analysis of purified human erythrocyte-derived AChE (28±7nM by DPV; 26±8nM by Ellman's method). The selectivity of this unmodified electrode system was compared to a range of biological sulfur-containing compounds including cysteine, homocysteine, glutathione and methionine as well as ascorbic acid. Preliminary studies also demonstrated the potential applicability of this electrochemical technique for the analysis of Donepezil in crude cholinesterase samples from anterior cortex homogenates of C57BL/6J mice.
Keywords: Abbreviations; AD; Alzheimer's disease; AChE; acetylcholinesterase; ATChI; acetylthiocholine iodide; ChEI; cholinesterase inhibitor; IC; 50; inhibitory concentration 50; DPV; differential pulse voltammetry; DTNB; 5,5′-dithiobis-2-nitrobenzoic acid; TCh; thiocholine; TNB; 5-thio-2-nitrobenzoate; V; i; inhibited reaction velocity; V; o; control reaction velocityAlzheimer's disease; Label-free; Electrochemical sensor; Differential pulse voltammetry; Acetylcholinesterase; Inhibitor
Colorimetric and fluorescent chemosensor for citrate based on a rhodamine and Pb2+ complex in aqueous solution by Chun-Yan Li; Yu Zhou; Yong-Fei Li; Xue-Fei Kong; Chun-Xiang Zou; Chao Weng (pp. 79-84).
•A novel rhodamine compound was synthesized and used to recognize citrate.•The chemosensor can be applied to detect citrate by color and fluorescent changes.•The chemosensor has been used for citrate in real samples successfully.In this paper we unveil a novel rhodamine compound based fluorescent chemosensor (1-Pb2+) for colormetric and fluorescent detection of citrate in aqueous solution. This is the first fluorescent chemosensor for citrate based on rhodamine compound. The comparison of this method with some other fluorescence methods for citrate indicates that the method can detect citrate in aqueous solution by both color changes and fluorescent changes with long emission wavelength. In the new developed sensing system, 1-Pb2+ is fluorescent due to Pb2+-induced fluorescence enhancement of 1. However, the addition of citrate may release 1 into the solution with quenching of fluorescence. The chemosensor can be applied to the quantification of citrate with a linear range covering from 1.0×10−7 to 5.0×10−5M and a detection limit of 2.5×10−8M. The experiment results show that the response behavior of 1-Pb2+ towards citrate is pH independent in medium condition (pH 6.0–8.0). Most importantly, the fluorescence changes of the chemosensor are remarkably specific for citrate in the presence of other anions (even those that exist in high concentration), which meet the selective requirements for practical application. Moreover, the response of the chemosensor toward citrate is fast (response time less than 1min). In addition, the chemosensor has been used for determination of citrate in urine samples with satisfactory results.
Keywords: Fluorescence; Chemosensor; Rhodamine; Pb; 2+; Citrate
An ultrasensitive streptavidin-functionalized carbon nanotubes platform for chemiluminescent immunoassay by Zhanjun Yang; Juan Shen; Juan Li; Jing Zhu; Xiaoya Hu (pp. 85-91).
•An ultrasensitive chemiluminescent (CL) immunoassay strategy was developed.•This assay was preformed based on a streptavidin-functionalized MWCNTs platform.•The sensitivity displays 7.9-fold increase compared to that without MWCNTs.•This method provides a promising approach for ultrasensitive CL immunoassay.An ultrasensitive chemiluminescent (CL) immunoassay system was developed for the detection of tumor marker. This sandwich CL assay method was for the first time designed based on a highly efficient streptavidin-functionalized multi-walled carbon nanotubes (MWCNTs) platform. The glass slide was firstly silylanized with 3-gycidoxypropyltrimethoxysilane (GPTMS) to generate surface epoxy group functionality. Subsequently, the MWCNTs/chitosan solution was mixed with streptavidin solution, and a certain amount of the resulting suspension was dropped on the surface of the epoxy-activated glass substrate to form a firm streptavidin-functionalized MWCNTs platform. The biofunctionalized-MWCNTs platform shows large reactive surface area and excellent biocompatibility. The capture antibody can be efficiently immobilized on the biosensing platform surface based on the highly selective recognition of streptavidin to biotinylated antibody. Using α-fetoprotein (AFP) as model analyte, the proposed method exhibits wide linear range of 0.001–0.1ngmL−1 with a low detection limit down to 0.52pgmL−1. The CL immunoassay system displays 7.9-fold increase in the detection sensitivity compared to the immunosensor without using MWCNTs. Moreover, the resulting immunosensor demonstrates excellent specificity, good reproducibility, and acceptable stability. This streptavidin-functionalized MWCNTs platform opens a novel and promising avenue for fabricating ultrasensitive CL immunoassay system.
Keywords: Carbon nanotubes; Streptavidin; Functionalization; Chemiluminescent; Immunoassay; Tumor marker
A visual detection of protein content based on titration of moving reaction boundary electrophoresis by Hou-Yu Wang; Cheng-Ye Guo; Chen-Gang Guo; Liu-Yin Fan; Lei Zhang; Cheng-Xi Cao (pp. 92-99).
•A novel moving reaction boundary model formed with base and immobilized protein.•The moving reaction boundary titration developed for protein content assay.•Determining protein content via visual boundary displacement signal.•Weak influence of non-protein nitrogen reagents on the developed method.•Fast and sensitive analytical method as compared with classic Kjeldahl methodA visual electrophoretic titration method was firstly developed from the concept of moving reaction boundary (MRB) for protein content analysis. In the developed method, when the voltage was applied, the hydroxide ions in the cathodic vessel moved towards the anode, and neutralized the carboxyl groups of protein immobilized via highly cross-linked polyacrylamide gel (PAG), generating a MRB between the alkali and the immobilized protein. The boundary moving velocity ( VMRB) was as a function of protein content, and an acid–base indicator was used to denote the boundary displacement. As a proof of concept, standard model proteins and biological samples were chosen for the experiments to study the feasibility of the developed method. The experiments revealed that good linear calibration functions between VMRB and protein content (correlation coefficients R>0.98). The experiments further demonstrated the following merits of developed method: (1) weak influence of non-protein nitrogen additives (e.g., melamine) adulterated in protein samples, (2) good agreement with the classic Kjeldahl method ( R=0.9945), (3) fast measuring speed in total protein analysis of large samples from the same source, and (4) low limit of detection (0.02–0.15mgmL−1 for protein content), good precision (R.S.D. of intra-day less than 1.7% and inter-day less than 2.7%), and high recoveries (105–107%).
Keywords: Electrophoresis; Moving reaction boundary; Protein content; Titration