Field method for the determination of hexavalent chromium by ultrasonication and strong anion-exchange solid-phase extraction

A simple, fast, sensitive, and economical field method was developed and evaluated for the determination of hexavalent chromium (CrVI) in environmental and workplace air samples. By means of ultrasonic extraction in combination with a strong anion-exchange solid-phase extraction (SAE-SPE) technique, the filtration, isolation, and determination of CrVI in the presence of trivalent chromium (CrIII) and potential interferents was achieved. The method entails (1) ultrasonication in basic ammonium buffer solution to extract CrVI from environmental matrixes; (2) SAE-SPE to separate CrVI from CrIII and interferences; (3) elution/acidification of the eluate; (4) complexation of chromium with 1,5-diphenylcarbazide; and (5) spectrophotometric determination of the colored chromium-diphenylcarbazone complex. Several critical parameters were optimized in order to effect the extraction of both soluble (K2CrO4) and insoluble (PbCrO4) forms of CrVI without inducing CrIII oxidation or CrVI reduction. The method allowed for the dissolution and purification of CrVI from environmental and workplace air sample matrixes for up to 24 samples simultaneously in less than 90 min (including ultrasonication). The results demonstrated that the method was simple, fast, quantitative, and sufficiently sensitive for the determination of occupational exposures of CrVI. The method is applicable for on-site monitoring of CrVI in environmental and industrial hygiene samples.     

On-line overpressure thin-layer chromatographic separation and electrospray mass spectrometric detection of glycolipids

On-line thin-layer chromatographic separation and electrospray mass spectrometry (TLC/ESI-MS) has been accomplished by direct linking of a commercial overpressure TLC instrument, OPLC 50, and a Q-TOF mass spectrometer. Mass spectrometric detection sensitivity and chromatographic resolution achieved by this configuration were assessed using acidic glycolipids as examples. Under the optimized conditions, a sensitivity of 5 pmol of glycosphingolipid was readily demonstrated for TLC/ESI-MS and 20 pmol for TLC/ESI-MS/MS production scanning to derive the saccharide sequence and long chain base/fatty acid composition of the ceramide. Initial preconditioning of TLC plates is necessary to achieve high sensitivity detection by reducing chemical background noise. Plates can be used repeatedly (at least 10 times) for analysis, although this may result in a minor reduction in TLC resolution. Following solvent development, separated components on the TLC plates can be detected in the conventional way by nondestructive staining or UV absorption or fluorescence and can be stored for on-line TLC/ESI-MS analysis at a later stage without reduction in mass spectrometric detection sensitivity and chromatographic resolution. Aspects for further improvement of OPLC instrumentation include use of narrower TLC plate dimensions and refined design of the eluate exit system.     

A solid-phase microextraction device for the analysis of electrochemical reaction products by gas chromatography/mass spectrometry

Presented is a solid-phase microextraction syringe-electrode assembly that may be used to identify electrode reaction products. After an electrochemical experiment, the electrode within this syringe-electrode assembly can be introduced into the injection port of a gas chromatograph. Electrochemical reaction products can be analyzed, provided they adhere to the electrode surface and are amenable to gas chromatographic/mass spectrometric analysis. We highlight the potential usefulness of this device using well-known electrochemical reaction of quinones.     

Nonretentive solid-phase extraction of phosphorylated peptides from complex peptide mixtures for detection by matrix-assisted laser desorption/ionization mass spectrometry

Widespread interest in protein phosphorylation has led to the development of a variety of methods for the analysis of phosphoproteomes of different types of organisms. Many applications involve pretreatment of the sample before mass spectrometric measurement and can crucially improve the detection efficiency of individual phosphopeptides. Despite intense research efforts, separation and extraction of phosphorylated peptides, especially multiphosphorylated ones, remain challenging tasks and need to be further explored and expanded with unconventional approaches. In this study, we describe the application of nonretentive solid-phase extraction (SPE) to the analysis of phosphopeptides using the highly cross-linked polystyrene-divinylbenzene material Strata-X. This study indicates that the procedure allows for the preferential extraction of phosphopeptides regardless of their extent of phosphorylation. The Strata-X material primarily retains nonphosphorylated peptides by hydrophobic interaction, whereas the inherent hydrophilicity of phosphorylated peptides leads to their partitioning into the aqueous phase. Phosphopeptides that were rapidly segregated out of tryptic digest mixtures and collected in the early aqueous fractions generated intense signals in mass spectra. The method was developed using SPE Strata-X columns, then suited for detection and sequencing of phosphopeptides by miniaturizing the system to the scale of custom-made microcolumns. This provided fast isolation of phosphopeptides from protein digests along with direct MALDI on-target deposition. The possibility of on-target washing during sample preparation is also presented.     

Determination of proanthocyanidins in grape products by liquid chromatography/mass spectrometric detection under low collision energy

A method has been established for the identification of proanthocyanidins and quantification of individual monoproanthocyanidins using liquid chromatography/electrospray ionization-mass spectrometric detection (LC/ESI-MSD) for raw grape products. The separated monoproanthocyanidins and oligoproanthocyanidins were individually analyzed and identified by their molecular ion peaks using LC/MS. Using HPLC/ESI-MSD, the proanthocyanidin monomers, (+)-catechin (C), (-)-epicatechin (EC), (-)-catechin gallate (CG), and (-)-epicatechin gallate (ECG) in grape products were successfully quantified by LC/MS/MS detection of protonated molecular ions and characteristic fragment ions for each component under the optimized low collision energy level of 20%. For the investigated concentration ranges of C (21.88-11,200 ng/mL), EC (21.10-10,800 ng/mL), CG (36.72-18,800 ng/mL), and ECG (39.84-20,400 ng/mL), good linearities (r2 > 0.99) for standard curves were obtained. Validation of this method showed an accuracy that was well below 15% and precision (RSD) within 8% for the four compounds. The method proposed here is simple, sensitive, and allows a direct sample preparation procedure. This is the first method that enables the determination of individual monoproanthocyanidins in grape products without any solid-phase extraction.     

Determination of alkylbenzyldimethylammonium chlorides in river water and sewage effluent by solid-phase extraction and gas chromatography/mass spectrometry

This study presents a modified method to analyze alkylbenzyldimethylammonium chlorides (ABDACs) in river water and sewage effluent. The method involves mixed samples with linear alkylbenzenesulfonates (LAS) as a counterion to enhance the extraction of ABDAC residues from an RP-18 solid-phase cartridge by formation of hydrophobic ion-pair complexes. The ABDACs were then eluted with methanol-ethyl acetate (1:1, v/v) and formed to their corresponding alkyldimethylamines by the Hofmann degradation with potassium tert-butoxide. The alkyldimethylamines were then identified and quantitated by gas chromatograph/mass spectrometry (GC/MS). The results indicate that, in the presence of LAS, debenzylation of ABDACs occurs selectively at a temperature higher than 90 degrees C to produce the corresponding nonionic alkyldimethylamines. The method proposed herein provides a high precision and sensitivity for ABDACs, to quantitation at < or =0.1 microg/L in 500 mL of the water samples. The average recovery of ABDAC spiked water samples was 95% with relative standard deviations (RSD, n = 7) of 9%. The RSDs of three replicate environmental sample analyses ranged from 5 to 11%. Direct HPLC method was applied to evaluate the GC/MS method, and compatible results were observed.     

Performance evaluation of an in-injection port thermal desorption/gas chromatographic/negative ion chemical ionization mass spectrometric method for trace explosive vapor analysis

A gas chromatographic method utilizing thermal desorption of Tenax TA and sol-gel sorbent traps has been developed and validated for the analysis of trace explosive vapor with negative ion chemical ionization mass spectrometric detection. Sorbent tubes were packed with Tenax TA and sorbent particles prepared in-house by the sol-gel process. Thermal desorption was performed within a split/splitless injection port with minimal instrument modification. Performance was characterized by relative thermal desorption recovery, precision (reproducibility), linearity of the calibration, and method detection limits. Method validation was performed with a series of dinitrotoluenes, dinitrobenzene, trinitrotoluene, trinitrobenzene, two aminodinitrotoluenes, three nitroesters, and two nitramines. The performance of Tenax TA and the sol-gel sorbents is evaluated based on the method validation data. The method was applied to the analysis of trace explosive vapor collected and concentrated with sol-gel solid sorbent traps from the headspace of a smokeless gunpowder sample.     

Determination of methylmercury and butyltin compounds in marine biota and sediments using microwave-assisted acid extraction,solid-phase microextraction,and gas chromatography with microwave-induced plasma atomic emission spectrometric detection

A method is described for the determination of methylmercury and butyltin compounds in marine sediment and tissue using microwave-assisted acid extraction or digestion and solid-phase microextraction (SPME) followed by analysis using gas chromatography with microwave-induced plasma atomic emission spectrometric detection (GC-MIP-AES). Using the SPME-GC-MIP-AES method, enrichment factors for methylmercury and butyltin compounds of 50-100 were achieved, as compared to the typical hexane extraction, and measurements in marine tissue and sediment matrixes were possible at 1-2 microg/kg (methylmercury) and 10-100 ng/kg (butyltins). The SPME-GC-MIP-AES method was validated using several marine sediment and tissue matrix certified reference materials (CRMs) with certified values for methylmercury and butyltin compounds. The SPME-GC-MIP-AES method was used to measure methylmercury in four marine tissue CRMs ranging from oyster tissue at 13.0 +/- 1.0 microg/kg to fish tissue at 397 +/- 13 microg/kg (as Hg dry mass). Results from the SPME-GC-MIP-AES method were used in conjunction with results from other techniques to assign certified values for methylmercury in oyster, mussel, and fish tissue CRMs. Mono-, di-, and tributyltin were measured in three sediment CRMs at concentration levels of (0.08 +/- 0.03)-(0.35 +/- 0.05) mg/kg (as Sn dry mass).     

Simultaneous measurement of urinary bisphenol A and alkylphenols by automated solid-phase extractive derivatization gas chromatography/mass spectrometry

Bisphenol A (BPA) and alkylphenols (APs) are widely used industrial chemicals. BPA is used to manufacture polycarbonate plastic and epoxy resins; APs are used to make alkylphenol ethoxylates, common nonionic surfactants. BPA and APs can leach into the environment during industrial production and after degradation of the polycarbonate plastics and nonionic surfactants. Environmental exposure to these phenolic compounds has been associated with adverse reproductive and developmental effects in wildlife. We developed a sensitive and robust method for measuring BPA and six APs; 3-tert-butylphenol, 4-tert-butylphenol, 4-n-octylphenol, 4-tert-octylphenol, 4-n-nonylphenol, and technical-grade nonylphenol in urine. The method is based on the use of automated solid-phase extraction (SPE) coupled to isotope dilution-gas chromatography/mass spectrometry (GC/MS). During the automated SPE process, the phenols are both extracted from the urine matrix and derivatized, using pentafluorobenzyl bromide, on commercially available styrene-divinylbenzene copolymer-based SPE cartridges. After elution from the SPE column, the derivatized phenols in the SPE eluate are analyzed by GC/MS. The method, validated on spiked pooled urine samples and on urine samples from exposed persons, has limits of detection of approximately 0.1 ng in 1 mL of urine.     

A device for automated direct sampling and quantitation from solid-phase sorbent extraction cards by electrospray tandem mass spectrometry

A new solid-phase extraction (SPE) device in the 96-well format (SPE Card) has been employed for automated off-line sample preparation of low-volume urine samples. On-line automated analyte elution via SPE and direct quantitation by micro ion spray mass spectrometry is reported. This sample preparation device has the format of a microtiter plate and is molded in a plastic frame which houses 96 separate sandwiched 3M Empore sorbents (0.5-mm-thickness, 8-microm particles) covered on both sides by a microfiber support material. Ninety-six discrete SPE zones, each 7 mm in diameter, are imbedded into the sheet in the conventional 9-mm pitch (spacing) of a 96-well microtiter plate. In this study one-quarter of an SPE Card (24 individual zones) was used merely as a convenience. After automated off-line interference elution of applied human urine from 24 samples, a section of SPE Card is mounted vertically on a computer-controlled X, Y, Z positioner in front of a micro ion spray direct sampling tube equipped with a beveled tip. The beveled tip of this needle robotically penetrates each SPE elution zone (sorbent disk) or stationary phase in a serial fashion. The eluted analytes are sequentially transferred directly to a microelectrosprayer to obtain tandem mass spectrometric (MS/MS) analysis. This strategy precludes any HPLC separation and the associated method development. The quantitative determination of Ritalin (methylphenidate) from fortified human urine samples is demonstrated. A trideuterated internal standard of methylphenidate was used to obtain ion current response ratios between the parent drug and the internal standard. Human control urine samples fortified from 6.6 to 3300 ng/mL (normal therapeutic levels have been determined in other studies to be between 50 and 100 ng/mL urine) were analyzed and a linear calibration curve was obtained with a correlation coefficient of 0.9999, where the precision of the quality control (QC) samples ranged from 9.6% at the 24 ng/mL QC level to 1.2% at the 3000 ng/mL QC level, and the accuracy for the four levels of QC samples ranged from 98.1% to 100.3%. The QC samples were prepared at four concentrations which included 24, 240, 1200, and 3000 ng/mL, respectively. The run time per sample in this work was 1.5 min not including the sample preparation time.     

Determination of nicotine and other minor alkaloids in international cigarettes by solid-phase microextraction and gas chromatography/mass spectrometry

Nicotine, nornicotine, anabasine, and anatabine are the most abundant alkaloids in tobacco. Along with the addictiveness of nicotine, other properties, including their occurrence in tobacco at relatively high concentrations, and as the primary precursors for the highly carcinogenic tobacco-specific nitrosoamines, make these chemicals important from a public health standpoint Therefore, developing a fast and accurate quantitative method to screen large numbers of cigarette samples for these alkaloids was important. This report describes the first use of headspace analysis using solid-phase microextraction combined with gas chromatography/mass spectrometry for the unambiguous detection of tobacco alkaloids. Detection and confirmation of each analyte isestablished by both chromatographic retention times and the ratio of reconstructed ion chromatogram peak areas from characteristic quantitation ion and confirmation ion. Twenty-eight cigarette brands from 14 countries were analyzed. Surprisingly, the minor alkaloids' response factors varied considerably among different styles of cigarettes. Accurate quantification was achieved using a three-point standard addition protocol. The standard addition approach was essential to obtain accurate measurements by minimizing matrix effects that would otherwise have contributed to quantitation bias. Significant differences in the alkaloid profiles were measured in the different cigarette brands. These results strongly suggest that such differences reflect variations associated with blend compositions, tobacco quality, and manufacturing practices.     

Membrane-assisted solvent extraction of triazines, organochlorine, and organophosphorus compounds in complex samples combined with large-volume injection-gas chromatography/mass spectrometric detection

The performance of the fully automated membrane-assisted solvent extraction was investigated for 47 environmental contaminants (among them 30 organochlorine compounds, 9 organophosphorus compounds, and 7 triazines). The extraction took place in a 20-mL headspace vial filled with the aqueous sample and containing a polypropylene membrane bag with 1 mL of cyclohexane as extractant. This device was handled by a multipurpose sampler, which enabled the sample to be mixed at a defined temperature with subsequent large-volume injection of the organic extract taken out of the membrane bag. After optimization of extraction parameters, the method was validated for the three compound classes, triazines and organochlorine and organophosphorus compounds, using spiked distilled water. Then, the extraction yield of these analytes from several complex samples such as a natural and a synthetic wastewater, a bacterial culture, and orange juice was determined and compared to a conventional liquid-liquid extraction. Furthermore, the possibility of reducing matrix interference by adding salt, methanol, or detergent during membrane-assisted solvent extraction was investigated.     

Determination of clenbuterol in bovine liver by combining matrix solid-phase dispersion and molecular imprinted solid-phase extraction followed by liquid chromatography/electrospray ion trap multiple-stage mass spectrometry

Matrix solid-phase dispersion (MSPD) is a new sample pretreatment for solid samples. This technique greatly simplifies sample pretreatment but, nonetheless, the extracts often still require an extra cleanup step that is both laborious and time-consuming. The potential of combining MSPD with molecularly imprinted solid-phase extraction (MISPE) was investigated in this study. Liver samples were ground in a mortar with C18 sorbent and the homogenized mixture packed into an SPE cartridge and placed on top of a MISPE cartridge. Subsequently, clenbuterol was eluted from the MSPD cartridge onto the MISPE cartridge using acetonitrile containing 1% acetic acid. The ability of the molecularly imprinted polymer to selectively adsorb analyte in acetonitrile was exploited for re-extracting clenbuterol directly from this acetonitrile extract via the double cartridge tandem system. The analyte was eluted from the MISPE cartridge using acidified methanol. A clear eluate was obtained, which was subsequently evaporated, redissolved, and analyzed by HPLC electrochemical detection (ECD) or ion trap mass spectrometry (LC/IT-MS). The MISPE cartridge used in this study was imprinted using bromoclenbuterol, a structural analogue of clenbuterol, as the template. These MISPE cartridges showed excellent stability. The complete extraction procedure was rapid, and recoveries exceeded 90% for the target analyte. The method detection limit for the LC/IT-MS procedure was < 0.1 microg/kg. This method, therefore, satisfies the stringent requirements of European Union regulation EEC 2377/90.     

High-throughput sequential injection method for simultaneous determination of plutonium and neptunium in environmental solids using macroporous anion-exchange chromatography, followed by inductively coupled plasma mass spectrometric detection

This paper reports an automated analytical method for rapid and simultaneous determination of plutonium and neptunium in soil, sediment, and seaweed, with detection via inductively coupled plasma mass spectrometry (ICP-MS). A chromatographic column packed with a macroporous anion exchanger (AG MP-1 M) was incorporated in a sequential injection (SI) system for the efficient retrieval of plutonium, along with neptunium, from matrix elements and potential interfering nuclides. The sorption and elution behavior of plutonium and neptunium onto AG MP-1 M resin was compared with a commonly utilized AG 1-gel-type anion exchanger. Experimental results reveal that the pore structure of the anion exchanger plays a pivotal role in ensuring similar separation behavior of plutonium and neptunium along the separation protocol. It is proven that plutonium-242 ((242)Pu) performs well as a tracer for monitoring the chemical yield of neptunium when using AG MP-1 M resin, whereby the difficulties in obtaining a reliable and practicable isotopic neptunium tracer are overcome. An important asset of the SI setup is the feasibility of processing up to 100 g of solid substrates using a small-sized (ca. 2 mL) column with chemical yields of neptunium and plutonium being ≥79%. Analytical results of three certified/standard reference materials and two solid samples from intercomparison exercises are in good agreement with the reference values at the 0.05 significance level. The overall on-column separation can be completed within 3.5 h for 10 g of soil samples. Most importantly, the anion-exchange mini-column suffices to be reused up to 10-fold with satisfactory chemical yields (>70%), as demanded in environmental monitoring and emergency scenarios, making the proposed automated assembly well-suited for unattended and high-throughput analysis.     

Improved performance and maintenance in gas chromatography/isotope ratio mass spectrometry by precolumn solvent removal

The crucial step in current concepts to interface isotope ratio mass spectrometry (IRMS) to gas chromatography (GC) is efficient solvent removal. This is due to the essential postcolumn conversion of the analytes into simple gases, which is performed by either combustion or pyrolysis. The capacity of this step merely suffices to convert the analytes. Already small amounts of solvent present in the respective furnace can cause severe damage. In conventional GC/IRMS interfaces, the solvent is removed after passage of the GC column. Either back-flushing or flow diversion is employed for this purpose. Both techniques necessitate the use of numerous components such as unions, tee pieces, valves, and capillary connections. Often this results in significant deterioration of the chromatographic resolution. In contrast, accurate GC/IRMS measurements require baseline separation of adjacent peaks. Moreover, maintenance of conventional interfaces may be tedious and time consuming, mostly because the numerous connections are prone to leakage. In order to avoid these drawbacks, we propose a concept to efficiently remove the solvent before passage of the GC column. It is based on the use of a cooled injection system operated in solvent vent mode, where the solvent elimination is supported by an auxiliary pump. Most unions and tee pieces thus can be removed. The chromatographic resolution is considerably enhanced. In particular, analysis of high-boiling and polar compounds can be improved. At the same time, the maintenance of the system is significantly facilitated. Under the chosen conditions, partial losses of low-boiling analytes during solvent elimination were not associated with significant isotope fractionation.     

Parallel detection of intrinsic fluorescence from peptides and proteins for quantification during mass spectrometric analysis

Direct mass spectrometric quantification of peptides and proteins is compromised by the wide variabilities in ionization efficiency which are hallmarks of both the MALDI and ESI ionization techniques. We describe here the implementation of a fluorescence detection system for measurement of the UV-excited intrinsic fluorescence (UV-IF) from peptides and proteins just prior to their exit and electrospray ionization from an ESI capillary. The fluorescence signal provides a quantifiable measure of the amount of protein or peptide present, while direct or tandem mass spectrometric analysis (MS/MS) on the ESI-generated ions provides information on identity. We fabricated an inexpensive, modular fluorescence excitation and detection device utilizing an ultraviolet light-emitting diode for excitation in a ～300 nL fluorescence detection cell integrated into the fused-silica separation column. The fluorescence signal is linear over 3 orders of magnitude with on-column limits of detection in the low femtomole range. Chromatographically separated intact proteins analyzed using UV-IF prior to top-down mass spectrometry demonstrated sensitive detection of proteins as large as 77 kDa.     

Improvements on enzymatic hydrolysis of human hair for illicit drug determination by gas chromatography/mass spectrometry

The use of ultrasound energy for accelerating the pronase E enzymatic hydrolysis of human hair for extracting illicit drugs has been novelty tested. The enzymatic extracts obtained after 30 min of sonication in an ultrasonic water bath were subjected to an optimized solid-phase extraction process, which involved a solution of 2.0% (v/v) acetic acid in methanol as eluting solution and concentration by N2 stream evaporation. A gas chromatography/mass spectrometry method was used to separate and determine cocaine, benzoylecgonine, codeine, morphine, and 6-monoacethylmorphine in 20 min. Variables affecting ultrasound-assisted pronase E hydrolysis such as hydrolysis temperature, hydrolysis time, enzyme concentration, catalyzer (1,4-dithiothreitol) concentration, ionic strength, pH, and ultrasound frequency were simultaneously evaluated by a Plackett-Burman design 2(8) PBD of resolution III. The most statistically significant variables were ionic strength and pH, which means that analyte extraction is mainly attributed to pronase E activity. The optimization or evaluation of all the factors has led to an accelerated pronase E hydrolysis of human hair, which can be completed in 30 min. Results have been found to be statistically similar to those obtained with conventional pronase E hydrolysis. The accelerated method was finally applied to several human hair samples from multidrug abusers.     

Analysis of nicotine and its oxidation products in nicotine chewing gum by a molecularly imprinted solid-phase extraction

Chromatographic stationary phases showing exceptional selectivity for nicotine can be prepared by the technique of molecular imprinting. Such phases were used in the search for a rapid cleanup step for nicotine and some of its oxidation products in chewing gum formulations. Thus, using an organic mobile phase, the nicotine analytes from chewing gums dissolved in nonpolar solvent were retained, whereas the nonpolar matrix eluted close to the void peak. A subsequent switch to an acidic mobile phase resulted in elution of the analytes as one sharp peak. Due to weak binding of the less basic oxidation products, other imprinted polymers were tested, and the solid-phase extraction procedure was optimized. Polymers were prepared using various functional and cross-linking monomers, templates, porogens and thermal treatments. This resulted in phases that, when compared with a nonimprinted or a C18 reversed-phase column, showed significantly higher recoveries of the analytes. Furthermore, no bleeding of template from the phases could be detected. The cleanup step was coupled off-line to reversed-phase HPLC, and the efficiency of the analysis was compared with and without the cleanup step. Three out of four analytes were quantitatively recovered using the imprinted phase, whereas, using the nonimprinted phase, only nicotine was recovered. Without the cleanup step, none of the analytes could be determined using the reversed-phase HPLC method.     

Target and nontarget screening of organic micropollutants in water by solid-phase microextraction combined with gas chromatography/high-resolution time-of-flight mass spectrometry

The potential of gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC/TOF-MS) for screening of organic pollutants in water has been explored. After optimization of the solid-phase microextraction (SPME) step, where parameters such as fiber selection and addition of salt were studied, this extraction technique was applied to the analysis of different types of water samples. Investigation of 60 target organic pollutants, including pesticides, octyl/nonyl phenols, pentachlorobenzene, and polycyclic aromatic hydrocarbons (PAHs) was carried out by evaluating the presence of up to five representative m/z ions per analyte, measured at high mass accuracy, and the attainment of their Q/q (Q, quantitative ion; q, confirmative ion) intensity ratio. This strategy led to the detection of 4-t-octylphenol, simazine, terbuthylazine, chlorpyrifos, terbumeton, and terbutryn in several water samples at low part-per-billion levels. Full spectrum acquisition data generated by the TOF-MS analyzer also allowed subsequent investigation of the presence of polybrominated diphenyl ethers and several fungicides in samples after MS data acquisition, without the need to reanalyze the water samples. In addition, nontarget analysis was also tested by application of a deconvolution software. Several organic pollutants that did not form a part of the list of contaminants investigated were identified in the water samples, thanks to the excellent sensitivity of TOF-MS in full spectrum acquisition mode and the valuable accurate mass information provided by instrument. Bisphenol A, the antioxidant 3,5-di-tert-butyl-4-hydroxy-toluene (BHT), its metabolite 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHT-CHO), the polycyclic musk galaxolide, and the UV filter benzophenone were some of the compounds present in the water samples analyzed. SPME in combination with GC/TOF-MS has been proved to be an attractive and powerful approach for the rapid screening of multiclass organic pollutants in water, with very little sample manipulation and no solvent consumption. This combination provides to the analyst with information-rich MS data that facilitates the reliable identification of many different organic compounds in samples.     

Catalyzed hydrolysis of nerve gases by metal chelate compounds and potentiometric detection of the byproducts

A new method for detection of nerve gases, Sarin and Soman, was proposed on the basis of their catalyzed hydrolysis by metal chelate compounds and potentiometric detection of the byproduct, fluoride ion. Diisopropyl fluorophosphate (DFP) was used as a nerve gas mimic. The copper ion chelates shift the potential of the fluoride ion-selective electrode to more positive stable potential, which is beneficial for lowering the detection limit. In the presence of DFP, the electrode potential decreases rapidly with time due to the catalyzed hydrolysis of DFP and the production of fluoride ion. This method is sensitive, selective, and reproducible. The detection limit for DFP is 2 x 10(-6) M with a potential drop between 40 and 60 mV.