特丁二甲硅烷基衍生化气相色谱-质谱法检测尿中4种苯氧羧酸类除草剂

建立了尿中2,4-滴(2,4-D)、2,4-滴丙酸(2,4-DP)2、甲4氯(MCPA)和2甲4氯丙酸(MCPP)4种苯氧羧酸类除草剂的气相色谱-质谱(GC-MS)分析方法。尿样加氯化钠饱和,酸化后用乙醚萃取,萃取物进行特丁二甲硅烷基(TBDMS)衍生化后分析。尿中4种除草剂的浓度在3~3 000 ng/mL范围内工作曲线的线性关系良好,检出限在1 ng/mL以下,3、100和1 000 ng/mL水平加标回收率在97.0%~102.2%之间,精密度在6.2%~14.2%之间。该法灵敏,可用于中毒者和职业接触者尿中苯氧羧酸类除草剂的分析。     

Determination of anabolic steroids by gas chromatography/negative-ion chemical ionization mass spectrometry and gas chromatography/negative-ion chemical ionization tandem mass spectrometry with heptafluorobutyric anhydride derivatization

A gas chromatography/mass spectrometry (GC/MS) method is described which uses negative ion chemical ionization (NCI) and tandem mass spectrometry (MS/MS) for the determination of eight anabolic steroids in human urine. Eight anabolic steroids were derivatized by heptafluorobutyric anhydride (HFBA), and were determined using GC/NCI-MS and GC/NCI-MS/MS. The linear correlation coefficients for calibration in NCI-MS/MS were in the range 0.9880-0.9988. This method of derivatization with HFBA for use with GC/NCI was useful in determinations of 19-norandrosterone, boldenone, 19-noretiocholanolone, 2-methylandrosterone, nandrolone, 1-methyleneandrosterone, 1-methylandrosterone, 4-dihydroboldenone and mesterolone. The detection limits of this procedure were 5-20 ppb at a signal-to-noise (S/N) ratio of 3.     

食品中胆固醇色谱／质谱／质谱的测定

确立了用色谱／质谱／质谱测定食品中胆固醇的一种新方法，试样经乙酸乙酯提取后，ＧＣ／ＭＳ／ＭＳ测定分析，以胆固醇分子离子为母离了，以其子离子为定量分析的碎片离子。线性好，回收率高，方法可靠。     

气相色谱-串联质谱法测定土壤中的邻苯二甲酸酯

建立了土壤中6种邻苯二甲酸酯的气相色谱-串联质谱(GC-MS/MS)分析方法。土壤样品用超声提取,以二氯甲烷-丙酮(1:1, v/v)混合溶液为提取溶剂,提取液经Florisil小柱净化后,经HP-5MS色谱柱(30 m×0.25 mm×0.25 μm)分离,利用MS/MS的多反应监测(MRM)模式进行定性和定量。结果表明本方法可对样品中的邻苯二甲酸酯进行分析,在10～1000 μg/L质量浓度范围内,线性关系良好,相关系数为0.9973～0.9976;6种邻苯二甲酸酯的相对标准偏差(RSD)不大于14.3%, 2 μg/kg和10 μg/kg两个加标水平的回收率为72.9%～106.2%; 6种目标化合物的检出限为0.1～0.5 μg/kg。该方法快速准确、背景干扰较少、分析灵敏度较高,适用于土壤样品中邻苯二甲酸酯的分析。     

Gas chromatographic/mass spectrometric analysis of the essential oil of Houttuynia cordata Thunb by using on-column methylation with tetramethylammonium acetate

This paper describes a simple and novel on-column derivatization procedure used with gas chromatography/mass spectrometry (GC/MS) for the analysis of essential oil of Houttuynia cordata Thunb (HCT), a traditional Chinese medicine. In the procedure, the essential oil was obtained by hydrodistillation, and the fatty acid components were derivatized with tetramethylammonium acetate (TMAA) at 250 degrees C and identified by GC/MS. Methylation improved the determination of both the fatty acids and the other components in the essential oil of HCT. To obtain optimum methylation conditions, several important factors were investigated with pentadecane as the internal standard and a GC inlet temperature of 250 degres C. Tetramethylammonium hydroxide (TMAH) and TMAA were compared as the derivatization agent, and a 2:1 ratio of TMAA to capric acid was evaluated. Fatty acid methyl esters produced good chromatographic peak shapes and did not interfere with the determination of dodecanal and caryophyllene. TMAA is a neutral methylation reagent, and it yielded no side reactions during derivatization. It was found that the fatty acid content of the essential oil was about 81%; among the methylated fatty acids found were capric acid, methyl (43.66%), methyl laurate (16.15%), methyl hexadecanoate (9.27%), undecanoic acid, methyl (5.62%), methyl oleate (1.98%), and methyl linoleate (1.40%). Other major constituents were (-)-beta-pinene (1.02%), beta-myrcene (1.62%), 1-terpinen-4-ol (1.59%), decanal (1.49%), and 2-undecanone (1.47%). The results obtained demonstrated good efficiency for the procedure. Pure chromatograms allowed quantitation, which was obtained by total volume integration. The on-column derivatization procedure was simple to perform, and it improved the sensitivity, the peak resolution, and the selectivity of the GC/MS determination.     

顶空衍生化固相微萃取法测定酱油中3-氯-1,2丙二醇

建立顶空衍生化固相微萃取测定酱油中3-氯-1,2丙二醇(3-MCPD)的方法。聚乙二醇-二乙烯基苯(CW-DVB)萃取纤维先顶空吸附苯基硼酸,然后同时萃取和衍生化样品顶空气体中的3-MCPD和内标物d5-3-MCPD,衍生化产物在进样口热解吸,GC-MS检测,内标法定量,特征离子为m/z196、201。结果表明,样品中3-MCPD质量浓度为0.01~1mg/kg时,工作曲线的线性良好(r=0.9994),添加回收率为89%~104%,检出限为0.01mg/kg。     

气相色谱—质谱法测定水中的二苯羟乙酸

本文报道用气相色谱－质谱法鉴定和定量测定水样中的二苯羟乙酸。对二苯羟乙酸及其甲基化产物的色谱行为进行了探讨。讨论了ＧＣ进样口污染对测定二苯羟乙酸甲酯的影响。应用本方法测定了国际实验室之间比较试验水样中的二苯羟乙酸，分析结果与ＨＰＬＣ方法相一致。     

Determination of pentachlorophenol and tribromophenol in sawdust by ultrasound-assisted extraction and MEKC

An ultrasonic bar-assisted extraction and CE separation procedure for the determination of pentachlorophenol (PCP) and 2,4,6-tribromophenol (TBP) residues in sawdust was developed and applied. For this purpose, micellar electrokinetic capillary chromatography (MEKC) was used and compared with a GC/MS methodology. This methodology allowed the quantification of PCP and TBP in a concentration range of 2.5-12.0 mg/kg for TBP and 2.8-12.0 mg/kg for PCP. Different sample treatment processes were evaluated in order to extract these compounds from sawdust. Better results were obtained when the residues were extracted with ultrasound-assisted hexane, filtered, evaporated, dissolved in Na(2)CO(3), and injected into the CE equipment. The optimal option for GC/MS was extraction with Na(2)CO(3 )followed by a derivation using acetic anhydride and liquid-liquid extraction with hexane. This method allowed the quantification of TBP and PCP in sawdust in a concentration range of 0.19-12.00 mg/kg and 0.14-12.00 mg/kg, respectively. The CE method was compared with the GC/MS as reference method. The results were shown to be statistically similar by both methods for PCP as well as for TBP.     

Analysis of cholesterol oxidation products by Fast gas chromatography/mass spectrometry

The aim of the present study was to set‐up a Fast gas chromatography/mass spectrometry method for the analysis of cholesterol oxidation products (COPs). A silylated mixture of seven oxysterol standards was injected into a Fast GC/MS system. A capillary GC column (10 m×0.1 mm internal diameter×0.1 μm film thickness) coated with 95% dimethyl‐ and 5% diphenyl‐polysiloxane, was used. The method gave a fast (total analysis time=3.5 min) and satisfactory resolution (R>1.2) of the COPs standards, with a good repeatability and sensitivity, similar to those of conventional GC/MS; recoveries were tested on mice liver. Fast GC/MS method suitability for COPs analysis in food was also tested on an oxidized sardine fillet, which had been previously saponified and purified by NH₂ solid‐phase extraction (SPE); a good repeatability and sensitivity was also obtained. The analytical performance of the Fast GC/MS method for the determination of COPs, together with the consequent significant reduction of the analysis time and consumables, demonstrates that Fast GC/MS represents a valid alternative to conventional GC/MS and evinces the great potential of such an analytical technique, which could be applied for both food and biological samples.     

Simple and sensitive method for determination of nitrated polycyclic aromatic hydrocarbons in diesel exhaust particles by gas chromatography-negative ion chemical ionisation tandem mass spectrometry

An extremely simple and sensitive method was developed for determination of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs; mono-nitro-PAHs and dinitropyrenes) in diesel exhaust particles (DEPs) by gas chromatography-negative ion chemical ionisation tandem mass spectrometry (GC/NCI/MS/MS). We used two types of column in GC/NCI/MS/MS analysis. A polar column was used for determination of mono-nitro-PAHs, and a non-polar column was used for determination of dinitropyrenes and mono-nitro-PAHs except nitrofluoranthenes. The proposed method requires no clean-up procedure. The limits of detection ranged from 0.01 to 0.09 pg for all compounds tested. The applicability of the method to DEP samples was validated using diesel particulate standard reference materials (SRMs). Although DEPs contain complex matrices, all compounds could be detected easily in SRM2975 (diesel particulate matter) and SRM1975 (diesel particulate extract) without a clean-up procedure. The RSDs were less than 5% for all compounds examined. The quantitative results for SRMs exhibited good agreement with the available data in the literature. These results indicate that the proposed GC/NCI/MS/MS method is useful for determination of nitro-PAHs in DEP samples.     

Biological monitoring of 3-phenoxybenzoic acid in urine by an enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay (ELISA) method was employed for determination of the pyrethroid biomarker, 3-phenoxybenzoic acid (3-PBA) in human urine samples. The optimized coating antigen concentration was 0.5 ng/mL with a dilution of 1:4000 for the 3-PBA antibody and 1:6000 for the enzyme conjugate. Urine samples were hydrolyzed with concentrated hydrochloric acid; extracted with dichloromethane and solvent-exchanged into a methanol/buffer solution, prior to analysis in a 96-microwell plate immunoassay. Quantitative recoveries of 3-PBA were obtained for fortified urine samples by ELISA (92 ± 18%) as well as by gas chromatography/mass spectrometry (GC/MS) (90 ± 13%). The overall method precision of these samples was within ±20% for both the ELISA and GC/MS methods. Analytical results from over one hundred urine samples showed that the ELISA and GC/MS data were highly correlated, with a correlation coefficient of 0.95. At the 10 ng/mL comparative concentration level, the false positive rate was 0% and the false negative rate was 0.8% for ELISA when using GC/MS as the reference method. The ELISA method has a suitable low detection limit for 3-PBA to assess pyrethroid exposures in non-occupational settings.     

Analysis of odorous trichlorobromophenols in water by in-sample derivatization/solid-phase microextraction GC/MS

The simultaneous determination of several odorous trichlorobromophenols in water has been carried out by an in-sample derivatization headspace solid-phase microextraction method (HS-SPME).The analytical procedure involved their derivatization to methyl ethers with dimethyl sulfate/NaOH and further HS-SPME and gas chromatography-mass spectrometry (GC/MS) determination. Parameters affecting both the derivatization efficiency and headspace SPME procedures, such as the selection of the SPME fiber coating, derivatization–extraction time and temperature, were studied. The commercially available polydimethylsiloxane (PDMS) 100 μm and Carboxen-polydimethylsiloxane-divinylbenzene (CAR-PDMS-DVB) fibers appeared to be the most suitable for the simultaneous determination of these compounds. The precision of the HS-SPME/GC/MS method gave good relative standard deviations (RSDs) run-to-run between 9% and 19% for most of them, except for 2,5-diCl-6-Br-phenol, 2,6-diCl-3-Br-phenol and-2,3,6-triBr-phenol (22%, 25% and 23%, respectively). The method was linear over two orders of magnitude, and detection limits were compound dependent but ranged from 0.22 ng/l to 0.95 ng/l. The results obtained for water samples using the proposed SPME procedure were compared with those found with the EPA 625 method, and good agreement was achieved. Therefore, the in-sample derivatization HS-SPME/GC/MS procedure here proposed is a suitable method for the simultaneous determination of odorous trichlorobromophenols in water.     

Comparison of GC–MS and MEKC methods for caffeine determination in preworkout supplements

In this study, GC–MS‐ and MEKC‐based methods for determination of caffeine (CAF) in preworkout supplements were developed and validated. The proposed protocols utilized minimal sample preparation (simple dilution and syringe filtration). The developed methods achieved satisfactory validation parameters, i.e. good linearity (R² > 0.9988 and R² > 0.9985 for GC–MS‐ and MEKC‐based method, respectively), satisfactory intra‐ and interaccuracy (within 92.6–100.7% for method utilizing GC–MS and 92.1–110.3% for protocol based on MEKC) and precision (CV < 15.9% and CV < 6.3% for GC–MS‐ and MEKC‐based method, respectively) and recovery (within 100.1–100.8% for method utilizing GC–MS and 101.5–106.2% for protocol based on MEKC). The LOD was 0.03 and 3 μg/mL for method utilizing GC–MS and MEKC, respectively. The CAF concentrations determined by GC–MS‐ and MEKC‐based methods were found to be in the range of 8.53–11.23 and 8.20–11.61 μg/mL, respectively. Taking into consideration information on the labels, the investigated supplements were found to contain from 110.0 to 167.3% of the declared CAF content, which confirmed the literature reports on incompatibility of the declared product compositions with real ones. Nevertheless, the consumption of examined supplements as recommended by producers did not lead to exceeding the CAF safe limit of 400 mg per day. Additionally, the MEKC‐based method allowed for detection and identification of vitamin B3 and B6 in all of the investigated supplement samples, which demonstrated that MEKC‐based protocols may be an appropriate assays for simultaneous determination of CAF and vitamins.     

Experimental design for the study of two derivatization procedures for simultaneous GC analysis of acidic herbicides and water chlorination by-products

Two well known derivatization procedures, pentafluorobenzylation and BF(3)/methanol esterification, were compared for their applications to GC analysis of acidic water micropollutants (chloroacetic and phenoxyalkanoic acids). A two-level factorial design was used to determine the influence of different parameters and their interactions on each derivatization process. The studied parameters are the reaction time, the amount of reagent (PFBBr) or catalyst (BF(3)) and the temperature. Considering pentafluorobenzylation, the most influential factors are the concentration of PFBBr and the interaction ;temperature-time', which improve the derivatization efficiency. However, a PFBBr concentration of 250 mg l(-1) in the reaction medium cannot be exceeded because of the increase in interfering by-products in GC/ECD. Moreover, chloroacetic acid derivatives are co-eluted with these compounds. This disadvantage was not observed in the operating conditions of GC/MS. The improved pentafluorobenzylation procedure allows the direct determination of the derivatives in GC/ECD without any purification step. The average detection limits are 1.6 and 80 mug l(-1), respectively in GC/ECD and in GC/MS. The reproducibility is 13%. For the BF(3)/methanol esterification, the interactions ;BF(3) concentration-temperature' and ;BF(3) concentration-reaction time' are significant and have a negative effect on the derivatization yield. A linear model was therefore proposed and validated in the experimental area under study. All the compounds studied were detected in GC/MS, and the average detection limit is 2 mug l(-1). The reproducibility is around 7%. Therefore, after optimization, BF(3)/methanol esterification followed by GC/MS is as sensitive as pentafluorobenzylation used with GC/ECD, and more reproducible.     

Simultaneous determination of dimethylarsinic acid and monomethylarsonic acid after derivatization with thioglycol methylate by gas chromatography/mass spectrometry

A gas chromatography/mass spectrometry (GC/MS) method has been developed to determine two methylated arsenic species in human urine samples. The yield of derivatization for dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) using thioglycol methylate (TGM) was measured. The detection limit for the derivatized DMA and MMA using the GC/MS method are 0.95 and 0.8 ng cm-3, respectively. This simple and rapid method has good precision and accuracy. Fragmentation routes of derivatized MMA and DMA are suggested on accurate mass measurements.     

Quantitative evaluation of benzene, toluene, and xylene in the larvae of Drosophila melanogaster by solid-phase microextraction/gas chromatography/mass spectrometry for potential use in toxicological studies

A simple, rapid, and solvent-free method for quantitative determination of benzene, toluene, and Xylene in exposed Drosophila larvae was developed using headspace solid-phase microextraction (HS-SPME) coupled to GC/MS. Larvae fed on standard Drosophila food mixed with benzene, toluene, and Xylene for 48 h were homogenized in Milli-Q water. Extraction of benzene, toluene, and Xylene was performed at 65 degrees C for 30 min on the SPME fiber (silica-fused). Subsequently, the fiber was desorbed in the GC injection port, followed by GC/MS analysis in the selected-ion monitoring mode. An external calibration curve was used for the quantification of benzene, toluene, and Xylene in the exposed organism. Recoveries were in the range of 78-82% (intraday) and 76-81% (interday) in larvae, and 91-96% (intraday) and 87-92% (interday) in the diet. LOD with an S/N of 3:1 and LOQ with an S/N of 10:1 were in the range of 0.01-0.023 and 0.034-0.077 microg/L, respectively. Percent RSD values for benzene, toluene, and Xylene were in the range of 0.50-0.81 (intraday) and 0.89-1.23 (interday) for retention time, and 2.16--3.85 (intraday) and 2.99-4.95 (interday) for peak concentration, showing good repeatability. This method was sensitive enough to quantitate benzene, toluene, and Xylene in small exposed organisms like Drosophila larvae. The SPME/GC/MS method developed may have wider applications in various in vivo toxicological studies.     

Determination of residues of 446 pesticides in fruits and vegetables by three-cartridge solid-phase extraction-gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry

A method was developed for determination of residues of 446 pesticides in fruits and vegetables through the use of cleanup by a 3-cartridge solid-phase extraction-gas chromatography/ mass spectrometry (GC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). Fruit and vegetable samples (20 g) were extracted with 40 mL acetonitrile, salted out, and centrifuged. Half of the supernatant was passed into an Envi-18 cartridge, eluted with acetonitrile, and cleaned up with Envi-Carb and aminopropyl Sep-Pak cartridges in series after concentration of the eluates. Pesticides were eluted with acetonitrile-toluene (3 + 1, v/v), and eluates were concentrated to 0.5 mL and then added into internal standards after solvent exchange with 2 mL hexane and used for determination of 383 pesticides by GC/MS. The other half of the supernatant was concentrated to 1 mL and cleaned up with Envi-Carb and aminopropyl Sep-Pak cartridges in series. Pesticides were eluted with acetonitrile-toluene (3 + 1, v/v), and the eluates were concentrated to 0.5 mL, dried with nitrogen gas, diluted to 1.0 mL with acetonitrile-water (3 + 2, v/v), and used for determination of 63 pesticides by LC/MS/MS. The limit of detection for the method was 0.2-600 ng/g depending on the individual pesticide. In the method, fortification recovery tests at high, medium, and low levels were conducted on 6 varieties of fruits and vegetables, i.e., apples, oranges, grapes, cabbage, tomatoes, and celery, with average recoveries falling within the range of 55.0-133.8% for 446 pesticides, among which average recoveries between 60.0-120.0% accounted for 99% of the results. The relative standard deviation was between 2.1-39.1%, of which a relative standard deviation of 2.1-25.0% made up 96% of the results. Experiments proved that the method was applicable for determination of residues of 446 pesticides in fruit and vegetables.     

尿中有机酸的毛细管气相色谱—质谱轮廓分析—用于苯丙酮尿症的诊断

应用毛细管气相色谱-质谱轮廓分析方法,测定了33例2.5～4.5岁健康儿童尿中有机酸种类及含量和8例拟诊为苯丙酮尿症儿童尿中的有机酸,结果表明患儿尿样中苯丙酮酸、苯乙酸、邻羟基苯乙酸、对羟基苯乙酸高于正常值10～470倍。为苯丙酮尿症的确诊提供了可靠方法。     

固相微萃取/气相色谱/质谱联用测定水中的2,4-二硝基苯酚

研究了水中痕量2,4-二硝基苯酚的固相微萃取（SPME）方法,得到了2,4-二硝基苯酚的SPME最佳萃取条件：水溶液调pH2,并用NaCl他和,在室温下直接萃取30min,气相色谱／质谱分析时,纤维探针在270℃下脱附3min。所建立的方法适于快速、方便地测定水中2,4-二硝基苯酚,不需浓缩和预处理。     

Application of tandem mass spectrometry combined with gas chromatography to the routine analysis of ethyl carbamate in stone-fruit spirits

Gas chromatography (GC) coupled to mass spectrometry (MS) operated in selected ion monitoring (SIM) mode is currently the method of choice for the determination of the toxic contaminant ethyl carbamate in alcoholic beverages. However, even after extensive sample cleanup over diatomaceous earth columns, the identity of ethyl carbamate often cannot be ascertained with confidence, due to inconsistent ratios of the SIM ions m/z 62, 74 and 44 because the qualifier ions are highly susceptible to interferences. Therefore, a new method combining GC and tandem MS using a triple-quadrupole instrument is introduced to determine ethyl carbamate in stone-fruit spirits. For quantitative analysis the characteristic transitions of m/z 74 --> 44 and m/z 62 --> 44 for ethyl carbamate as well as m/z 64 --> 44 for the deuterated internal standard ethyl carbamate-d5 were monitored in the multiple reaction monitoring (MRM) mode. In the validation studies, ethyl carbamate exhibited good linearity with a regression coefficient of 1.000. The limits of detection and quantitation were 0.01 and 0.04 mg/L. The recovery of the method was 100.4 +/- 9.4%. The precision never exceeded 7.8% (intraday) and 10.1% (interday) and the trueness never exceeded 11.3% (intraday) and 12.2% (interday) at any of the concentrations examined, indicating good assay accuracy. A good agreement of analytical results between a previously developed GC/MS SIM method and the GC/MS/MS MRM procedure was found (R=0.987). Regarding the validation data, the procedure is sensitive, selective and reproducible. The applicability of the developed method was demonstrated by the investigation of 70 stone-fruit spirits from commercial trade. The ethyl carbamate concentration of the samples ranged between 0.07 and 7.70 mg/L (mean 1.21 mg/L). The main advantage of the developed GC/MS/MS method is the reliability of the results without the need for time-consuming confirmatory analyses.