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Analytica Chimica Acta (v.733, #)
Miniaturized nucleic acid amplification systems for rapid and point-of-care diagnostics: A review by Farhan Ahmad; Syed A. Hashsham (pp. 1-15).
Display Omitted► Analysis of the parameters responsible for rapid microPCR is performed. ► Progress and requirement of completely integrated microPCR systems are discussed. ► Current status of microLAMP systems is presented. ► Advantages of microLAMP over microPCR towards rapid and POC diagnostics are discussed.Point-of-care (POC) genetic diagnostics critically depends on miniaturization and integration of sample processing, nucleic acid amplification, and detection systems. Polymerase chain reaction (PCR) assays have extensively applied for the diagnosis of genetic markers of disease. Microfluidic chips for microPCR with different materials and designs have been reported. Temperature cycling systems with varying thermal masses and conductivities, thermal cycling times, flow-rates, and cross-sectional areas, have also been developed to reduce the nucleic acid amplification time. Similarly, isothermal amplification techniques (e.g., loop-mediated isothermal amplification or LAMP), which are still are emerging, have a better potential as an alternative to PCR for POC diagnostics. Isothermal amplification techniques have: (i) moderate incubation temperature leading to simplified heating and low power consumption, (ii) yield high amount of amplification products, which can be detected either visually or by simple detectors, (iii) allow direct genetic amplification from bacterial cells due to the superior tolerance to substances that typically inhibit PCR, (iv) have high specificity, and sensitivity, and (v) result in rapid detection often within 10–20min. The aim of this review is to provide a better understanding of the advantages and limitations of microPCR and microLAMP systems for rapid and POC diagnostics.
Keywords: Polymerase chain reaction; Loop-mediated isothermal amplification; Miniaturized nucleic acid analysis system; Point-of-care; Diagnostics; Microfluidics
Systematic ratio normalization of gas chromatography signals for biological sample discrimination and biomarker discovery by Benoist Lehallier; Jérémy Ratel; Mohamed Hanafi; Erwan Engel (pp. 16-22).
Display Omitted► We developed a novel processing procedure of GC data dubbed systematic ratio normalization (SRN). ► SRN consists in selecting the most discriminative inter-compound log-ratios. ► SRN enables to improve the discrimination of groups of biological samples. ► SRN uncovers the most biologically relevant biomarkers. ► SRN emphasizes the factor-of-interest while diminishing the weight of disturbance factors.The present paper introduces a new gas chromatography data processing procedure dubbed systematic ratio normalization (SRN) enabling to improve both sample set discrimination and biomarker identification. SRN consists in (1) calculating, for each sample, all the log-ratios between abundances of chromatography-analyzed compounds, then (2) selecting the log-ratio(s) that best maximize the discrimination between sample-sets. The relevance of SRN was evaluated on two data sets acquired through gas chromatography–mass spectrometry as part of separate studies designed (i) to discriminate source-origins between vegetable oils analyzed via an analytical system exposed to instrument drift (data set 1) and (ii) to discriminate animal feed between meat samples aged for different durations (data set 2). Applying SRN to raw data made it possible to obtain robust discrimination models for the two data sets by enhancing the contribution to the data variance of the factor-of-interest while stabilizing the contribution of the disturbance factor. The most discriminant log-ratios were shown to employ the most relevant biomarkers presenting relative independence of the factor-of-interest as well as co-behavior of the disturbance effects potentially biasing the discrimination, such as instrument drift or sample biochemical changes. SRN can be run a posteriori on any data set, and might be generalizable to most of separating methods.
Keywords: Systematic ratio normalization; Discrimination; Biomarker; Gas chromatography–mass spectrometry; Volatile compounds
Electrochemical determination of arsenic(III) on mercaptoethylamine modified Au electrode in neutral media by Dongyue Li; Jing Li; Xiaofang Jia; Yanchao Han; Erkang Wang (pp. 23-27).
In this work, the mercaptoethylamine modified Au electrode (MEA/Au electrode) was investigated for arsenic detection by differential pulse anodic stripping voltammetry (DPASV). This method offers obvious advantages that it not only suppresses the Cu(II) interference, but also can detect the As(III) in natural water samples at the original pH with high stability and good reproducibility.Display Omitted► A simple, sensitive sensing platform for As(III) has been fabricated in neutral media. ► The as-prepared sensor suppresses the Cu(II) interference. ► This method monitors As(III) at the original pH of natural water samples. ► This method was successfully applied for the determination of As(III) in real samples. ► The as-prepared sensor has high stability and good reproducibility.A simple, rapid and sensitive sensing platform for the detection of As(III) has been fabricated in neutral media based on the mercaptoethylamine modified Au electrode. A wide detection range of 0.2–300μgL−1 and a low detection limit of 0.02μgL−1 were obtained with a preconcentration time of 100s under optimal conditions. Compared with previous studies, this work shows obvious advantages that it not only suppresses the Cu(II) interference, but also can detect the As(III) in natural water samples at the original pH avoiding high concentration acidic media. Moreover, the practical application of the proposed method was verified in the lake water sample determination.
Keywords: Anodic stripping voltammetry; Arsenic(III); Copper(II) interference; Neutral media
Enzymatic single-drop microextraction for the assay of ethanol in alcohol-free cosmetics using microvolume fluorospectrometry detection by Noelia Cabaleiro; Inmaculada de la Calle; Carlos Bendicho; Isela Lavilla (pp. 28-33).
Display Omitted► An enzyme-based assay in drop format is performed for ethanol determination in alcohol-free cosmetics. ► An aqueous drop containing ADH and NAD is used as a probe to extract ethanol. ► Fluorescence changes are monitored by microvolume fluorospectrometry. ► Matrix effects from the cosmetic sample are not present using the headspace-SDME mode. ► LODs better than those obtained by other enzymatic-based methods are reached.A green assay based on the development of an enzymatic reaction in drop format under headspace single-drop microextraction conditions is described for the first time. An aqueous drop containing the enzyme alcohol dehydrogenase and the cofactor β-Nicotinamide adenine dinucleotide has been used as fluorescence probe for determining ethanol in alcohol-free cosmetics by microvolume fluorospectrometry. Experimental parameters affecting the microextraction performance were carefully optimized. Under the conditions employed, the contribution of other alcohols was found to be negligible. After 10min of microextraction, a detection limit of 0.04μgg−1 ethanol, a repeatability, expressed as relative standard deviation, of 5.3% for a 0.05mM ethanol standard and a preconcentration factor of 391, were reached. Accuracy of the proposed methodology was evaluated by comparison of calibration slopes corresponding to external calibration with aqueous standards and standard addition calibration. The method was successfully applied to different alcohol-free cosmetics (external calibration was carried out in all cases). Additional advantages such as simplicity and high sample throughput can be highlighted. The greenness profile of proposed methodology was established using NEMI criteria (US National Environmental Methods Index).
Keywords: Headspace-single-drop microextraction; Enzymatic probe; Ethanol assay; Alcohol-free cosmetics; Microvolume fluorospectrometry; Green method
On-line micro-volume introduction system developed for lower density than water extraction solvent and dispersive liquid–liquid microextraction coupled with flame atomic absorption spectrometry by Aristidis N. Anthemidis; Constantina Mitani; Paschalia Balkatzopoulou; Paraskevas D. Tzanavaras (pp. 34-37).
Display Omitted► A dispersive liquid–liquid micro extraction method for lead and copper determination. ► A micro-volume transportation system for extractant solvent lighter than water. ► Analysis of natural water samples.A simple and fast preconcentration/separation dispersive liquid–liquid micro extraction (DLLME) method for metal determination based on the use of extraction solvent with lower density than water has been developed. For this purpose a novel micro-volume introduction system was developed enabling the on-line injection of the organic solvent into flame atomic absorption spectrometry (FAAS). The effectiveness and efficiency of the proposed system were demonstrated for lead and copper preconcentration in environmental water samples using di-isobutyl ketone (DBIK) as extraction solvent. Under the optimum conditions the enhancement factor for lead and copper was 187 and 310 respectively. For a sample volume of 10mL, the detection limit (3s) and the relative standard deviation were 1.2μgL−1 and 3.3% for lead and 0.12μgL−1 and 2.9% for copper respectively. The developed method was evaluated by analyzing certified reference material and it was applied successfully to the analysis of environmental water samples.
Keywords: Dispersive liquid–liquid microextraction; On-line; Atomic spectrometry; Copper; Lead
Direct analysis in real time mass spectrometry and multivariate data analysis: A novel approach to rapid identification of analytical markers for quality control of traditional Chinese medicine preparation by Shanshan Zeng; Lu Wang; Teng Chen; Yuefei Wang; Huanbiao Mo; Haibin Qu (pp. 38-47).
Display Omitted► DART-MS combined with PCA was used to rapidly identify markers of herbal preparation. ► Salvianolic acids and saccharides were simultaneously determined with DART-MS. ► DART-MS spectra obtained from batches of Danshen injections were processed using PCA. ► Candidate markers of Danshen injection were recognized from the contribution plots.The paper presents a novel strategy to identify analytical markers of traditional Chinese medicine preparation (TCMP) rapidly via direct analysis in real time mass spectrometry (DART-MS). A commonly used TCMP, Danshen injection, was employed as a model. The optimal analysis conditions were achieved by measuring the contribution of various experimental parameters to the mass spectra. Salvianolic acids and saccharides were simultaneously determined within a single 1-min DART-MS run. Furthermore, spectra of Danshen injections supplied by five manufacturers were processed with principal component analysis (PCA). Obvious clustering was observed in the PCA score plot, and candidate markers were recognized from the contribution plots of PCA. The suitability of potential markers was then confirmed by contrasting with the results of traditional analysis methods. Using this strategy, fructose, glucose, sucrose, protocatechuic aldehyde and salvianolic acid A were rapidly identified as the markers of Danshen injections. The combination of DART-MS with PCA provides a reliable approach to the identification of analytical markers for quality control of TCMP.
Keywords: Direct analysis in real time; Mass spectrometry; Analytical marker; Traditional Chinese medicine preparation; Principal component analysis
Selective melamine detection in multiple sample matrices with a portable Raman instrument using surface enhanced Raman spectroscopy-active gold nanoparticles by Laura C. Mecker; Katherine M. Tyner; John F. Kauffman; Sergey Arzhantsev; Daniel J. Mans; Connie M. Gryniewicz-Ruzicka (pp. 48-55).
Display Omitted► Initial work for field deployable screening of melamine in multiple matrices. ► Without extensive sample preparation, colorimetric screening offered false results. ► Surface enhanced Raman spectroscopy was performed with a portable Raman system. ► Gold nanoparticles as SERS substrates offered selective detection of melamine. ► Limits of detection in seven food and pharmaceutical matrices were 100–200mgL−1.Melamine adulteration of food and pharmaceutical products is a major concern and there is a growing need to protect the public from exposure to contaminated or adulterated products. One approach to reduce this threat is to develop a portable method for on-site rapid testing. We describe a universal and selective method for the detection of melamine in a variety of solid matrices at the 100–200μgL−1 level by surface enhanced Raman spectroscopy (SERS) with gold nanoparticles. With minimal sample preparation and the use of a portable Raman spectrometer, this work will lead to field-based screening for melamine adulteration. Citrate coated gold nanoparticles (Au NPs) were investigated for both colorimetric and Raman-based responses. Several non-hazardous solvents were evaluated in order to develop a melamine extraction procedure safe for field applications. Au NP agglomerates formed by the addition of isopropanol (IPA) prior to sample introduction enhanced the Raman signal for melamine and eliminated matrix interference for substrate formation. The melamine Raman signal resulted in a 105 enhancement through the use of Au NP agglomerates. To our knowledge, we have developed the first portable SERS method using Au NPs to selectively screen for the presence of melamine adulteration in a variety of food and pharmaceutical matrices, including milk powder, infant formula, lactose, povidone, whey protein, wheat bran and wheat gluten.
Keywords: Melamine; Nanoparticles; Surface enhanced Raman spectroscopy
Tracking growth hormone abuse in sport: A comparison of distinct isoform-based assays by J. Bosch; M. Ueki; G. Such-Sanmartín; J. Segura; R. Gutiérrez-Gallego (pp. 56-63).
Display Omitted► Detection of recombinant human growth hormone abuse in sport. ► Comparison between different immunoassays employed. ► Dissection of the antibody specificity of all antibodies by SPR. ► Final validation with a dedicated human clinical trial.Detecting recombinant human growth hormone (rhGH) abuse in sport remains one of the major challenges in doping control. We have compared two different approaches to detect the hGH (human growth hormone) abuse. The first measures the concentrations of the 22kDa hGH isoform (rec assay) and pituitary derived isoforms (pit assay) and a ratio rec/pit is obtained. The second measures the concentrations of 22 and 20kDa hGH isoforms and also a ratio 22/20kDa is derived.Using a single set (nine healthy male subjects, 7 days, 0.026mg/kg/day of rhGH, 2 week wash out period) both approaches were compared. To quantify the agreement between the immunoassays, B.A. (Bland–Altman) analysis and P.r. (Pearson correlation) were used. To fully understand the assay readings, all relevant antibodies were characterised by surface plasmon resonance (SPR).In either approach the ratio numerator produces similar results and the denominator determines both signal-amplitude and time-frame of possible application. The rec vs pit approach displays a higher distinctive capacity to detect hGH abuse but the complex binding properties of the capture antibodies make it very difficult to evaluate the precise contributions of the individual hGH variants to the assay result. In the 22 vs 20 approach, the 20kDa hGH concentration measures determine its applicability.Both approaches are based on a different principle, should be preferably applied within 24h after rhGH administration, and are perfectly comparable given the results obtained. The reduced time frame of application indicates that their principle application should be preferably in an out-of-competition setting.
Keywords: Abbreviations; hGH; human growth hormone; WADA; World Anti Doping Agency; rhGH; recombinant hGH; phGH; pituitary hGH; mAb; monoclonal antibody; NIBSC; National Institute for Biological Standards and Control; SPR; surface plasmon resonance; WOO; window of opportunity; ILMA; immunoluminometric assay; LIA; luminiscent immuno assayGrowth hormone; Isoform; Marker proteins; Immunoassay; Doping
Development and evaluation of a loop-mediated isothermal amplification method in conjunction with an enzyme-linked immunosorbent assay for specific detection of Salmonella serogroup D by Hadi Ravan; Razieh Yazdanparast (pp. 64-70).
Display Omitted► Detection of Salmonella serogroup D serovars by LAMP-ELISA technique. ► LAMP-ELISA provides a detecting method with a minimum equipment dependency. ► LAMP-ELISA provides an accurate and easy-to-use method for detection of pathogens.Loop-mediated isothermal amplification in conjunction with enzyme-linked immunosorbent assay (LAMP-ELISA) provides a sensitive, specific and cost-effective method for detection of etiological causes of infections. The present study developed a reliable LAMP-ELISA diagnostic kit for identification of Salmonella serogroup D strains and evaluated its potential use in the detection of Salmonella serovars Enteritidis and Typhi. The LAMP-ELISA assay used a serogroup D/A-specific primer set to amplify a region of the prt gene, followed by hybridization of the digoxigenin-labeled products to a highly specific oligonucleotide probe for exact identification of serogroup D serovars. Among the bacteria tested, a positive reaction was only observed for strains belong to Salmonella serogroup D. The detection limit of the LAMP-ELISA assay was 4CFU per tube, which was lower than PCR-ELISA assay with the same target gene (50CFU per tube). Finally, the technique was successfully applied to an artificially contaminated meat sample with a detection limit 103CFUmL−1, which was 10 times more sensitive than PCR-ELISA. Overall, the LAMP-ELISA assay could be used as a sensitive alternative method to PCR-ELISA for the specific detection of Salmonella serogroup D serovars in routine food microbiology or clinical laboratories worldwide.
Keywords: LAMP enzyme-linked immunosorbent assay; PCR enzyme-linked immunosorbent assay; Salmonella; serogroup D; prt; gene
Organoboron compounds as Lewis acid receptors of fluoride ions in polymeric membranes by Martyna Jańczyk; Agnieszka Adamczyk-Woźniak; Andrzej Sporzyński; Wojciech Wróblewski (pp. 71-77).
Display Omitted► Organoboron Lewis acid receptors for fluoride anions in ion-selective electrodes. ► Super-Nernstian potentiometric response of PVC membrane based on phenylboronic acid. ► Mechanism of the electrode response proposed and supported by19F NMR studies. ► Variation of the stoichiometry of the boronic acid/fluoride complexes in membrane. ► Nernstian response measured for membranes based on phenylboronic acid ester.Newly synthesized organoboron compounds – 4-octyloxyphenylboronic acid (OPBA) and pinacol ester of 2,4,6-trifluorophenylboronic acid (PE-PBA) – were applied as Lewis acid receptors of fluoride anions. Despite enhanced selectivity, the polymer membrane electrodes containing the lipophilic receptor OPBA exhibited non-Nernstian slopes of the responses toward fluoride ions in acidic conditions. Such behavior was explained by the lability of the B–O bond in the boronic acids, and the OH−/F− exchange at higher fluoride content in the sample solution. In consequence, the stoichiometry of the OPBA–fluoride complexes in the membrane could vary during the calibration, changing the equilibrium concentration of the primary anion in membrane and providing super-Nernstian responses. The proposed mechanism was supported by19F NMR studies, which indicated that the fluoride complexation proceeds more effectively in acidic solution leading mainly to PhBF3− species. Finally, the performances of the membranes based on the phenylboronic acid pinacol ester, with a more stable B–O bond, were tested. As it was expected, Nernstian fluoride responses were recorded for such membranes with worsened fluoride selectivity.
Keywords: Organoboron compounds; Boronic acids; Lewis acid receptors; Fluoride receptors; Ion-selective electrodes
Label-free sensing of pH and silver nanoparticles using an “OR” logic gate by Dik-Lung Ma; Hong-Zhang He; Victor Pui-Yan Ma; Daniel Shiu-Hin Chan; Ka-Ho Leung; Hai-Jing Zhong; Lihua Lu; Jean-Louis Mergny; Chung-Hang Leung (pp. 78-83).
Display Omitted► A DNA logic gate for silver nanoparticles and pH has been constructed. ► A platinum(II) complex produces a luminescence response to the analyte. ► The logic gate performs “OR” operations with a switch-on luminescent output. ► The system selectively detects nanomolar silver nanoparticles in aqueous solution.Many natural phenomena are associated with the presence of two or more separate variables. We report here an “OR” DNA logic gate based on a luminescent platinum(II) switch-on probe for silver nanoparticles and pH, both of which may be considered putative indicators of pollution. The modulation of metal complex/double-stranded DNA complex phosphorescence by Ag+ and H+ was used to construct a simple, rapid and label-free method for the label-free detection of pH and nanomolar Ag+ ions and nanoparticles in aqueous solutions with high selectivity.
Keywords: Label-free detection; Logic gate; Silver nanoparticle; Platinum(II) complex; Luminescent probe
Simultaneous electrokinetic and hydrodynamic injection with on-line sample concentration via micelle to solvent stacking in micellar electrokinetic chromatography by Joselito P. Quirino; Agnes T. Aranas (pp. 84-89).
Display Omitted► Simultaneous electrokinetic and hydrodynamic injection with micelle to solvent stacking was shown. ► Up to 4000-fold improvement in peak height of cationic drugs compared to typical injection. ► LODs were from 0.6 to 4.2ngmL−1 in micellar electrokinetic chromatography. ► Detection of ngmL−1 drugs spiked in inlet effluent was achieved without off-line concentration. ► To maintain a stable stacking boundary, mild conditions for injection was required.Simultaneous electrokinetic and hydrodynamic injection (SEHI) of organic cations (tricyclic antidepressant and beta blocker drugs) with on-line sample concentration using micelle to solvent stacking (MSS) was studied in micellar electrokinetic chromatography. Compared to conventional injection, >300-fold improvements in signals were obtained by hydrodynamic injection. However, with SEHI the amount of sample ions introduced into the capillary was increased which afforded a higher gain of up to 4000-fold without compromise to separation efficiency. The electrokinetic injection at negative polarity (anode at the detector end) introduced the micelle bound analytes. The hydrodynamic injection also maintained the MSS boundary inside the capillary. The stability of the MSS boundary affected SEHI where mild conditions that were low voltage as well as pressure injection were desired. The limits of detection were in the range from 0.6–4.2ngmL−1. A strategy for optimization was described and the method was applied to the ngmL−1 analysis of spiked wastewater after simple dilution and centrifugation.
Keywords: On-line sample concentration; Micelle to solvent stacking; Capillary electrophoresis; Cations; Drugs; Simultaneous electrokinetic and hydrodynamic injection
Bioconjugation of trypsin onto gold nanoparticles: Effect of surface chemistry on bioactivity by Helmut Hinterwirth; Wolfgang Lindner; Michael Lämmerhofer (pp. 90-97).
Display Omitted► Size and spacer affect bioactivity of nanoparticulate trypsin reactor. ► Increase of GNP's size increases activity of bound trypsin. ► Increase of spacer length increases amount and activity of immobilized enzyme by factor 6. ► Decrease of digestion time up to less than 1h when trypsin immobilized onto GNPs. ► Reduced auto-digestion compared to trypsin in-solution.The systematic study of activity, long-time stability and auto-digestion of trypsin immobilized onto gold nanoparticles (GNPs) is described in this paper and compared to trypsin in-solution. Thereby, the influence of GNP's size and immobilization chemistry by various linkers differing in lipophilicity/hydrophilicity and spacer lengths was investigated with regard to the bioactivity of the conjugated enzyme. GNPs with different sizes were prepared by reduction and simultaneous stabilization with trisodium citrate and characterized by UV/vis spectra, dynamic light scattering (DLS), ζ-potential measurements and transmission electron microscopy (TEM). GNPs were derivatized by self-assembling of bifunctional thiol reagents on the nanoparticle (NP) surface via dative thiol-gold bond yielding a carboxylic acid functionalized surface. Trypsin was either attached directly via hydrophobic and ionic interactions onto the citrate stabilized GNPs or immobilized via EDC/NHS bioconjugation onto the carboxylic functionalized GNPs, respectively. The amount of bound trypsin was quantified by measuring the absorbance at 280nm. The activity of bound enzyme and its Michaelis Menten kinetic parameter K m and v max were measured by the standard chromogenic substrate Nα-Benzoyl-DL-arginine 4-nitroanilide hydrochloride (BApNA). Finally, digestion of a standard protein mixture with the trypsin-conjugated NPs followed by analysis with LC–ESI-MS and successful MASCOT search demonstrated the applicability of the new heterogenous nano-structured biocatalyst. It could be shown that the amount of immobilized trypsin and its activity can be increased by a factor of 6 using a long hydrophilic spacer with simultaneous reduced auto-digestion and reduced digestion time. The applicability of the new trypsin bioreactor was proven by digestion of casein and identification of α- as well as κ-casein by subsequent MASCOT search.
Keywords: Enzyme immobilization; Self-assembling monolayer; Enzyme activity; Protein digestion; Auto-digestion; Mass spectrometryAbbreviations; GNP; gold nanoparticle; GNP-trypsin; GNP immobilized trypsin; DLS; dynamic light scattering; TEM; transmission electron microscopy; SPR; surface plasmon resonance; PEG; polyethylene glycol; MHA; 16-mercaptohexadecanoic acid; EDC; N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride; NHS; N-hydroxysuccinimide; BApNA; N; α; -benzoyl-DL-arginine 4-nitroanilide hydrochloride; ZP; zeta potential
Determination of relative molecular weights of fluorescent components in dissolved organic matter using asymmetrical flow field-flow fractionation and parallel factor analysis by C.W. Cuss; C. Guéguen (pp. 98-102).
Typical fractogram and deconvolution fractions for leachate DOM (top) showing EEMs captured at (1) low, (2) intermediate and (3) high molecular weight. The peak label is based on Coble's nomenclature (1996).Display Omitted► Correlation between fluorescing components with molecular weight fractions. ► Size- and sample-dependencies of PARAFAC components are found. ► Tyrosine-like constituents are smaller in size than the humic-like constituents.Dissolved organic matter in aquatic systems is of variable structure and composition. Asymmetrical flow field-flow fractionation coupled to UV/vis diode array and fluorescence detectors (AF4–DAD–EEM) was used to assess the size and optical properties of dissolved organic matter. The results were analyzed using parallel factor analysis (PARAFAC) and statistical fractogram deconvolution to correlate fluorescing components with molecular weight fractions. This coupling, which is shown for the first time in this work, is a powerful method capable of revealing novel information about the size properties of PARAFAC components. Tyrosine/polyphenol-like fluorescence (peak B) was significantly correlated ( p<0.05) with the smallest size group (relative molecular weight=310±10Da), microbial humic-like and terrestrial visible humic-like fluorescence (peaks M, C, A) with the intermediate size group (1600±150Da), and terrestrial fulvic-like and tryptophan/polyphenol-like fluorescence (peaks A and T) with the largest size group (4300±660Da).
Keywords: Parallel factor analysis; Dissolved organic matter; Excitation–emission matrix; Deconvolution; Fluorescence; Chemometrics
Analytical evaluation of BEA zeolite for the pre-concentration of polycyclic aromatic hydrocarbons and their subsequent chromatographic analysis in water samples by Walter B. Wilson; Andréia A. Costa; Huiyong Wang; José A. Dias; Sílvia C.L. Dias; Andres D. Campiglia (pp. 103-109).
Display Omitted► BEA zeolite is used to pre-concentrate polycyclic aromatic hydrocarbons from water samples. ► The pre-concentration obtained with BEA have led to excellent analytical figures of merit. ► One milliliter aliquots are sufficient to obtain excellent precision at the parts-per-trillion concentration. ► The limits of detection varied between 1.1 (anthracene) and 49.9ngL−1 (indeno[1,2,3-cd]pyrene). ► The recovery values meet the criterion for regulated polycyclic aromatic hydrocarbons.The analytical performance of BEA – a commercial zeolite – is evaluated for the pre-concentration of fifteen Environmental Protection Agency – polycyclic aromatic hydrocarbons and their subsequent HPLC analysis in tap and lake water samples. The pre-concentration factors obtained with BEA have led to a method with excellent analytical figures of merit. One milliliter aliquots were sufficient to obtain excellent precision of measurements at the parts-per-trillion concentration level with relative standard deviations varying from 4.1% (dibenzo[a,h]anthracene) to 13.4% (pyrene). The limits of detection were excellent as well and varied between 1.1 (anthracene) and 49.9ngL−1 (indeno[1,2,3-cd]pyrene). The recovery values of all the studied compounds meet the criterion for regulated polycyclic aromatic hydrocarbons, which mandates relative standard deviations equal or lower than 25%. The small volume of organic solvents (100μL per sample) and amount of BEA (2mg per sample) makes sample pre-concentration environmentally friendly and cost effective. The extraction procedure is well suited for numerous samples as the small working volume (1mL) facilitates the implementation of simultaneous sample extraction. These are attractive features when routine monitoring of numerous samples is contemplated.
Keywords: Zeolites; Beta powder; Polycyclic aromatic hydrocarbons; Solid-phase extraction; High-performance liquid chromatography; Water analysis