Quantitative analysis of triphenylboron in environmental water samples by liquid chromatography/mass spectrometry.

Liquid chromatography/mass spectrometry (LC/MS) has been applied to the analysis of triphenylboron, which has been produced as a substitute for organotin compounds, in water. Although commercial triphenylboron compounds are produced as pyridinyl complexes, the chemical form in water is supposed to be mainly triphenylboron after liberating pyridine. The triphenylborons were extracted from water with an Empore C18 extraction disk under acidic condition, and the extracts were introduced directly into a liquid chromatograph-mass spectrometer equipped with a negative ion electrospray ionization interface. Identification of the compounds was performed with specific ions produced from the triphenylboron, and a quantitative analysis was carried out using the peak areas. The average recoveries from distilled water, seawater and river water at 0.30 ng/ml were 92.3, 100 and 85.3%, respectively. A detection limit of 0.023 ng/ml for triphenylboron was achieved.     

Determination of endocrine-disrupting compounds in environmental samples using gas and liquid chromatography with mass spectrometry

This paper describes certain applications for endocrine-disrupting compounds determination. LC-MS was applied using an electrospray ionization (ESI) technique in positive mode for alcohol polyethoxylates and nonylphenol and octylphenol polyethoxylates (NPEOn and OPEOn), and in negative mode for 4-nonylphenol (4-NP) and 4-octylphenol (4-OP) to determine targeted compounds in wastewater and sludge. GC-MS and GC-MS-MS were used to determine 4-NP, 4-tert.-octylphenol (4-t-OP), bisphenol A, estradiol-17beta, estriol estrone, testosterone, 17alpha-ethynylestradioL cholesterol, coprostan-3-ol, coprostan and coprostan-3-one in both surface water and wastewater after derivatization with N,O-bis(trimethyl-silyl)trifluoroacetamide (BSTFA). Extraction from the water samples was by an SPE technique, using either a copolymeric (Oasis HLB) or C18 silica sorbents, depending on the target contaminants. Extraction from the sludge samples was by a Soxtec system using methanol. Percentage recoveries for most of the selected compounds, using either a copolymeric (Oasis HLB) or C18 silica sorbents, were satisfactory (>60%). Quantification limits for the target compounds were at ppb levels in both water and sludge samples when using LC-ESI-MS in both positive and negative modes. They reached ppt levels in water when using GC-MS (in large volume injection mode) and GC-MS-MS. The results revealed 4-NP, NPEOn and AEOs in sludge samples at a concentration range of 1.3-8.5 microg/g, and NPEOn, OPEOn and other compounds, such as coprostan and bisphenol A, in surface water and/or wastewater samples at concentrations ranging from the ppt to ppb levels.     

New liquid chromatography/electron ionization mass spectrometry methods in water analysis

A method to extract and analyze organic compounds from water is presented. A solid phase micro-trap (micro-SPE) directly connected to the micro-analytical column is used. Sensibility and specificity needed for trace analysis are guaranteed by mass spectrometric electron ionization (EI) detection. A new micro-HPLC/EI-MS interface called Capillary-EI (Cap-EI) is described. The ultimate evolution of this interface is also presented: in this extremely simplified interface the analytes are nebulized, vaporized and ionized in the small volume of the ion source. This interface, called Direct-EI, exploits nano- and micro-HPLC columns with a mobile phase flow rates ranging from 0.3 to 1.5 microL/min. Contemporary use of micro SPE, Cap-EI or Direct-EI gives us a powerful technique to identify and quantify organic pollutants at part per billion level (ppb).     

Quantitative determination of acetylcholine in microdialysis samples using liquid chromatography/atmospheric pressure spray ionization mass spectrometry

A fast, simple and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed for the determination of acetylcholine in rat brain microdialysis samples. The chromatographic separation was achieved in 3 min on a reversed-phase column with isocratic conditions using a mobile phase containing 2% (v/v) of acetonitrile and 0.05% (v/v) of trifluoroacetic acid (TFA). A stable isotope-labeled internal standard was included in the analysis and detection was carried out with a linear ion trap mass spectrometer using selected reaction monitoring (SRM). Analyte ionization was performed with an atmospheric pressure chemical ionization (APCI) source without applying discharge current (atmospheric pressure spray ionization). This special ionization technique offered significant advantages over electrospray ionization for the analysis of acetylcholine with reversed-phase ion-pairing chromatography. The lower limit of quantification was 0.15 nM (1.5 fmol on-column) and linearity was maintained over the range of 0.15-73 nM, providing a concentration range that is significantly wider than that of the existing LC/MS methods. Good accuracy and precision were obtained for concentrations within the standard curve range. The method was validated and has been used extensively for the determination of acetylcholine in rat brain microdialysis samples.     

Sonic spray ionization interface for liquid chromatography-mass spectrometry

A sonic spray ionization (SSI) interface for liquid chromatography-mass spectrometry (LC-MS) analysis was optimized for analysis of 2-[(1R)-3-[bis(1-methylethyl)amino]-1-phenylpropyl]-4-methyl-phenol (tolterodine), used as a model drug substance, and the influence of different parameter settings was evaluated using factorial design. A comparison between SSI and electrospray ionization (ESI) was made for tolterodine, tolterodine metabolites, and a set of steroids.SSI was found to give slightly poorer repeatability and broader peaks for tolterodine compared to ESI. However, there was no significant difference in chromatographic peak shape, and the repeatability using SSI was similar to that obtained using ESI if a ratio (area of tolterodine/area of metabolite) was used. In this study, the sensitivity was higher using SSI. For the analysis of pregnanolone, less water loss was obtained using SSI, probably due to less energy being transferred to the analyte upon ionization.     

Countering matrix effects in environmental liquid chromatography-electrospray ionization tandem mass spectrometry water analysis for endocrine disrupting chemicals

In recent years, despite the increasing success of liquid chromatography (LC) coupled to tandem mass spectrometry (MS), reports on matrix susceptibility have shown the limitations of the this powerful analytical technique. Matrix effects (MEs) result from co-eluting residual matrix components affecting the ionization efficiency of target analytes and can lead to erroneous results. The present work evaluates the matrix effect of environmental water samples on 35 endocrine disrupting chemicals (EDCs) in negative and positive LC-ESI-MS/MS. It was shown that mobile-phase additives could significantly influence matrix effects. Addition of acids resulted in a severe signal suppression (average ME%: <65%), and 1 mM ammonium formate increased the average ME% to 84%. The importance of an efficient sample clean-up and internal standardization also was demonstrated. Cleaner extracts resulted in reduced matrix effects (average ME%: 89%) and labeled internal standards proved to have a beneficial effect especially on signal reproducibility (average CV% 4.2% versus 2.6%). The results from the present work indicate that evaluation of matrix effects should become an integrated part of quantitative LC-ESI-MS/MS method development and validation.     

Solid-phase microextraction liquid chromatography/tandem mass spectrometry for the analysis of chlorophenols in environmental samples

Liquid chromatography with atmospheric pressure chemical ionisation mass spectrometry (LC/APCI-MS), using negative ion detection in a triple quadrupole instrument, was used for the determination of chlorophenols (CPs) in environmental samples. In-source collision-induced dissociation (CID) was compared with MS/MS fragmentation. In general, less fragmentation was observed in MS/MS as compared with in-source CID, with the latter providing more intense fragment ions due to chemical ionisation. Under MS/MS conditions [M - H - HCl](-) was the main fragment ion observed for all compounds except for pentachlorophenol, which showed no fragmentation. For multiple reaction monitoring (MRM) acquisition mode, the transition from [M - H](-) to [M - H - HCl](-) was selected, leading to detection limits down to 0.3 ng injected. Direct and headspace-solid-phase microextraction (HS-SPME) were used as preconcentration procedures for the analysis of CPs in wood and in industrially contaminated soils. CPs were quantified by standard addition, which led to good reproducibility (RSD between 4 and 11%) in both SIM and MRM modes, and detection limits down to ng/g. The combination of MS/MS and in-source CID allowed confirmation of the presence of CPs in environmental samples.     

Quantitative determination of three sulfonamides in environmental water samples using liquid chromatography coupled to electrospray tandem mass spectrometry

An analytical method was developed to detect the three sulfonamides para-toluenesulfonamide (p-TSA), ortho-toluenesulfonamide (o-TSA) and benzenesulfonamide (BSA) in environmental water samples at concentrations down to 0.02 microg/L using liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). Wastewater, surface water, groundwater and drinking water samples from Berlin (Germany) were analysed for all three compounds which appear to be ubiquitously present in the aquatic environment. p-TSA was found in high concentrations in the wastewater (<0.02-50.8 microg/L) and in groundwater below a former sewage farm (<0.02-41 microg/L), and in lower concentrations in the surface water (<0.02 to 1.15 microg/L) and drinking water (<0.02-0.27 microg/L). o-TSA and BSA were detected in considerably lower concentrations. The study makes clear that p-TSA should be monitored because of its comparatively high concentration in Berlin's drinking water.     

高效液相色谱-电喷雾串联质谱法检测环境水样中22种抗生素类药物

建立了高效液相色谱-电喷雾串联质谱(HPLC-ESI MS/MS)分析环境水样中22种抗生素类药物的方法。采用HLB固相萃取柱对环境水样中的目标化合物进行富集、净化,然后以6 mL氨水-甲醇(5:95, v/v)溶液洗脱。收集的洗脱液经氮气吹干至1 mL,然后进行HPLC-ESI MS/MS分离分析。色谱流动相A相为甲醇-乙腈(1:1, v/v), B相为0.3%(体积分数)甲酸水溶液(含0.1%(体积分数)甲酸铵,pH 2.9);色谱柱为XTerra MS C18柱。质谱检测采用正离子扫描,多反应监测模式。分别以自来水和污水作为基质,22种抗生素类药物的加标平均回收率分别为54.9%～130%和57.4%～138%,相对标准偏差(n=3)分别为2.85%～28.6%和2.02%～23.2%;方法的检出限为0.05～0.5 ng/L。将建立的方法应用于北京市高碑店湖和小清河水样的分析,结果表明在两个水样中均有部分抗生素类药物检出。     

Two-dimensional analysis of phospholipids by capillary liquid chromatography/electrospray ionization mass spectrometry

A phospholipid mixture extracted from cultured cells was directly analyzed by capillary (Cap) liquid chromatography (LC)/electrospray ionization (ESI) mass spectrometry (MS). Using a quadrupole mass spectrometer, we analyzed positive molecular ions, negative molecular ions, positive fragment ions and negative fragment ions under four different functions. In the analysis of the elution patterns of the phospholipids, a two-dimensional map, in which the first dimension is elution time and the second dimension is mass, proved useful. Consequently, four different maps can be obtained by each of four different functions. Among them, from negative fragment ions at high cone voltage in the negative ion mode, ions that originated from acyl fatty acid and phosphorylcholine, phosphorylethanolamine and cyclic inositol phosphate can be detected at specific elution times. The map from positive fragment ions at high cone voltage in the positive ion mode indicated ions such as diradylglycerol and derivatives of 1-alkyl or 1-alkenyl cyclic phosphatidic acid from phosphatidylethanolamine (PE), and phosphorylcholine from choline-containing phospholipids. The map produced from positive molecular ions indicated choline-containing phospholipids such as phosphatidylcholine, sphingomyelin, lysophosphatidylcholine and PE. The map of negative molecular ions effectively indicated acidic phospholipids such as phosphatidylinositol. We were able to obtain more than 500 molecular species of phospholipids by this method within a few hours immediately after extraction from culture cells using a mixture of chloroform and methanol (2:1). In this context, we concluded that the combination of Cap-LC and ESIMS seems to be very effective in the analysis of phospholipid classes and their molecular species.     

Quantitative analysis of imazamox herbicide in environmental water samples by capillary electrophoresis electrospray ionization mass spectrometry

Capillary electrophoresis-mass spectrometry (CE-MS) with an electrospray ionization interface was applied for the quantitative analysis of imazamox pesticide in well water, potable water, and pond water. The detector response for imazamox was determined to be linear over the concentration range of 50-1 ng/ml. The limits of quantitation and detection of the method were determined to be 200 and 20 ng/l for imazamox compound in each type of water sample, respectively. The total sample preparation and CE-MS analysis time was under 2 h.     

Development of a solid-phase extraction with capillary liquid chromatography tandem mass spectrometry for analysis of estrogens in environmental water samples

Capillary liquid chromatography (cLC) hyphenated with tandem mass spectrometry (MS-MS) was used to separate and quantitate trace concentrations of five estrogens in aqueous samples. New C(18)-based sorption materials bound to the silica support by monomeric and polymeric mechanisms were compared and tested for solid-phase extraction (SPE) of selected analytes with respect to optimization of their preconcentration yield. Application of an endcapped, monomer-bound preconcentration Discovery DSC-18Lt column under the optimized conditions provides yields in the range from 95 to 100% with a high repeatability (n=3, RSD≤7.2%). Using the electrospray ionization in the positive mode (ESI+), the cLC-MS-MS system (the Zorbax SB C18 capillary column and a binary mobile phase of acetonitrile and water containing 0.1% formic acid in both the components) was optimized to attain a sufficient retention of the early eluting estriol, a satisfactory resolution of the analytes and the maximum sensitivity of the determination. Both the isocratic and gradient elution were used and the optimized gradient method permitted analyses of aqueous environmental samples in 14 min within a linearity range from 6.1 to 25.0 (LOQ of analytes) to 500 ng/L and with a very good linearity (r>0.9981) for all the estrogens studied. The detection limits are in the range from 3.0 to 6.8 ng/L (1 μL injection volume). Six environmental water samples were analyzed and the studied estrogens were found in the Vltava river sample collected in Prague (13.2 ng/L for 17β-estradiol) and in the inlet to the wastewater treatment plant in Prague, at an overall concentration of 371.4 ng/L.     

High-resolution liquid chromatography/electrospray ionization time-of-flight mass spectrometry combined with liquid chromatography/electrospray ionization tandem mass spectrometry to identify polyphenols from grape antioxidant dietary fiber

Grape antioxidant dietary fiber (GADF) is a dietary supplement that combines the benefits of both fiber and antioxidants that help prevent cancer and cardiovascular diseases. The antioxidant polyphenolic components in GADF probably help prevent cancer in the digestive tract, where they are bioavailable. Mass spectrometry coupled to liquid chromatography is a powerful tool for the analysis of complex plant derivatives such as GADF. We use a combination of MS techniques, namely liquid chromatography/electrospray ionization time-of-flight mass spectrometry (LC/ESI-TOF-MS) and liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) on a triple quadrupole, for the identification of the polyphenolic constituents of the soluble fraction of GADF. First, we separated the mixture into four fractions which were tested for phenolic constituents using the TOF system in the full scan mode. The high sensitivity and resolution of the TOF detector over the triple quadrupole facilitate the preliminary characterization of the fractions. Then we used LC/ESI-MS/MS to identify the individual phenols through MS/MS experiments (product ion scan, neutral loss scan, precursor ion scan). Finally, most of the identities were unequivocally confirmed by accurate mass measurements on the TOF spectrometer. LC/ESI-TOF-MS combined with MS/MS correctly identifies the bioactive polyphenolic components from the soluble fraction of GADF. High-resolution TOF-MS is particularly useful for identifying the structure of compounds with the same LC/ESI-MS/MS fragmentation patterns.     

Determination of paramethoxyamphetamine and other amphetamine-related designer drugs by liquid chromatography/sonic spray ionization mass spectrometry

Paramethoxyamphetamine (PMA) is an amphetamine-like designer drug that has emerged recently on the European illicit drug market. This drug has a wicked reputation, as a number of lethal intoxications have occurred. A method using high-performance liquid chromatography coupled to ion trap based mass spectrometry (LC/MS) is described for the determination of this compound together with 3,4-methylenedioxymethamphetamine (XTC or MDMA), amphetamine and 3,4-methylenedioxyamphetamine (MDA) in human matrices. A liquid/liquid extraction (LLE) was applied to whole blood, urine and postmortem tissues. Reversed-phase liquid chromatography was performed on a narrow-bore phenyl-type column at a flow rate of 0.3 mL/min. A switch box allowed disposal of early-eluting irrelevant material to waste, protecting the mass spectrometer from contamination. The column effluent was directed into an ion trap mass spectrometer by a sonic spray ionization (SSI) interface. The method was validated for all three matrices, proving the applicability of SSI even when dealing with complex biological matrices. The within-and between-day precisions were less than 17.5% and accuracy was below 16.2%. Weighted (1/x) quadratic calibration curves were generated ranging from 10 to 1000 ng/mL (blood and urine) or 20 to 2000 ng/g (tissue) and correlation coefficients (r(2)) always exceeded 0.995. In addition, the mass spectrum of PMA is given together with a proposed fragmentation pattern for the obtained LC/MS spectrum. This information can be useful for future identification of PMA with LC/MS in biological matrices as well as in confiscated powders or tablets.     

Stability studies of propoxur herbicide in environmental water samples by liquid chromatography-atmospheric pressure chemical ionization ion-trap mass spectrometry

Liquid chromatography-atmospheric pressure ionization ion-trap mass spectrometry has been investigated for the analysis of polar pesticides in water. The degradation behavior of propoxur, selected as a model pesticide belonging to the N-methylcarbamate group, in various aqueous matrices (Milli-Q water, drinking water, rain water, seawater and river water) was investigated. Two interfaces of atmospheric pressure ionization, atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI), were compared during the study. Propoxur and its transformation product (N-methylformamide) were best ionized as positive ions with both APCI and ESI, while another transformation product (2-isopropoxyphenol) yielded stronger signals as negative ions only with APCI. In addition, the effects of various pH, matrix type and irradiation sources (sunlight, darkness, indoor lighting and artificial UV lamp) on the chemical degradation (hydrolysis) were also assessed. From the kinetic studies of degradation, it was found that the half-life of propoxur was reduced from 327 to 161 h in Milli-Q water with variation of irradiation conditions from dark to sunlight exposure. Degradation rates largely increased with increasing pH. The half-life of the target compound dissolved in Milli-Q water under darkness decreased from 407 to 3 h when the pH of Milli-Q water was increased from 5 to 8.5. These suggest that hydrolysis of propoxur is light-intensity and pH-dependent. In order to mimic contaminated natural environmental waters, propoxur was spiked into real water samples at 30 microg/l. The degradation of propoxur in such water samples under various conditions were studied in detail and compared. With the ion trap run in a time-scheduled single ion monitoring mode, typical limits of detection of the instrument were in the range of 1-10 microg/l.     

Derivatization reagents in liquid chromatography/electrospray ionization tandem mass spectrometry

Liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) is one of the most prominent analytical techniques owing to its inherent selectivity and sensitivity. In LC/ESI-MS/MS, chemical derivatization is often used to enhance the detection sensitivity. Derivatization improves the chromatographic separation, and enhances the mass spectrometric ionization efficiency and MS/MS detectability. In this review, an overview of the derivatization reagents which have been applied to LC/ESI-MS/MS is presented, focusing on the applications to low molecular weight compounds.     

分散液相微萃取-气相色谱/质谱快速分析水中的硝基苯类化合物

建立了分散液相微萃取.气相色谱,质谱快速分析水中硝基苯、对硝基苯、1,3一二硝基苯和2,4-二硝基氯苯的新方法.将含有18μL氯苯(萃取荆)的0.25 mL丙酮(分散剂)作为萃取体系,快速注入到5.0 mL水溶液中.在4000r/min下离心2.0 min后,得到(10.0±0.5)μL沉积相(氯苯),取底部沉积相1.0μL进行气相色谱,质谱分析.方法线性范围0.5～50μg/L(r2=0.9986～0.9994),检出限0.2～0.5μg/L,相对标准偏差4.2%～7.3%(n=5).将该方法用于环境水样的测定,加标回收率72.9%～89.6%.