Determination of metrifonate and dichlorvos in whole blood using gas chromatography and gas chromatography-mass spectrometry

Analytical methods for determining metrifonate and dichlorvos in whole blood and a sampling procedure suitable for pharmacokinetic studies in man are described. Metrifonate concentrations were determined after chloroform extraction using gas chromatography-nitrogen-phosphorus detection. The within-assay coefficients of variation were 4 and 9% at 19.4 and 0.8 mumol/l (limits of determination), respectively. Dichlorvos was determined using gas chromatography-mass spectrometry of toluene extracts. The within-assay coefficients of variation were 2 and 5% at 225 and 50 nmol/l (limits of determination), respectively. Since both substances are chemically unstable, the blood was collected by dripping it directly from the vein into 0.74 M phosphoric acid.     

Determination of fragrance allergens in cosmetics by size-exclusion chromatography followed by gas chromatography-mass spectrometry

A method using size-exclusion chromatography (SEC) combined with gas chromatography-mass spectrometry (GC-MS) was developed for the quantitation of 24 restricted allergenic fragrance compounds in cosmetic samples. To achieve reproducible results fragrance calibration has to be performed with propyl acetate as a solvent containing a constant proportion of matrix components. With the exception of hydroxycitronellal (66+/-5%) all compounds showed good recovery rates in the range of 90-120%. The mean accuracy (relative error) was 1+/-10% for all 24 compounds in five spiked creams (10 mg/kg per allergen) and 8+/-34% in a reference sample (4-15 mg/kg). The biggest benefit compared to other methods is the flexible clean up with SEC which allows the determination of a large range of compounds in difficult matrices with GC-MS.     

Determination and identification of amiloride in human urine by high-performance liquid chromatography and gas chromatography-mass spectrometry.

A simple and sensitive high-performance liquid chromatographic method was developed to screen and determine amiloride (I) in human urine. The detection limit of the method is 0.12 micrograms/ml and the recovery of amiloride from urine was 80.4-85.5% at different concentrations. The coefficients of variation were less than 2.8 and 4.4% for intra- and inter-assays, respectively. Total urinary excretion of I in 24 h after oral administration of 5 mg or 15 mg of I ranged from 22.0 to 33.3% of the total dose for three different subjects. I could be detected in urine up to at least 44 h after a 5-mg dose and 72 h after a 15-mg dose. A gas chromatographic-mass spectrometric (GC-MS) confirmatory method was established based on the methanolysis of I to methyl 3,5-diamino-6-chloropyrazine-carboxylate (II). The di-N-trimethylsilyl derivative of II showed very good GC-MS properties and provided reliable structure information for confirmation analysis of I. This is the first time that a reliable GC-MS method has been reported for the detection of urinary I.     

Determination of oxprenolol in human plasma by high-performance liquid chromatography, in comparison with gas chromatography and gas chromatography-mass spectrometry

A high-performance liquid chromatographic method for the quantitative assay of oxprenolol in human plasma is described. After addition of alprenolol as internal standard, the compounds are extracted from plasma at alkaline pH into an organic phase and back-extracted into an acidic aqueous phase. Separation of the plasma components and metabolites was achieved on a reversed-phase column. Concentrations down to 66 nmol/l (20 ng/ml) can be determined with UV detection at 222 nm. This technique compares favourably with gas chromatographic and gas chromatographic-mass spectrometric methods.     

Determination of eperisone in human plasma by gas chromatography-mass spectrometry.

A gas chromatographic-mass spectrometric method was developed to determine eperisone hydrochloride, 4'-ethyl-2-methyl-3-piperidinopropiophenone hydrochloride, in human plasma over the concentration range 0.2-40 ng/ml. Excellent sensitivity was achieved by selection of a favorable fragment ion, m/z 98, of eperisone and reduction of heat decomposition of eperisone by using a splitless injector and a shortened capillary column. The method described here allows the determination of plasma concentrations as low as 0.2 ng/ml, the concentration attained 6 h after a single oral administration of 50 mg. At eperisone hydrochloride concentrations higher than 0.5 ng/ml, the mean inter-day variation of accuracy of the assay was less than 12%.     

Determination of ink photoinitiators in packaged beverages by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry

A new analytical method, using gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) techniques, was developed for the determination in packaged food beverages of five ink photoinitiator residues: 2-isopropylthioxanthone (ITX), benzophenone, 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB), 1-hydroxycyclohexyl-1-phenyl ketone (IRGACURE 184) and ethyl-4-dimethylaminobenzoate (EDAB). Samples were extracted from selected beverages (milk, fruit juices and wine) and relative packagings, using n-hexane and dichloromethane, respectively, purified on solid-phase extraction (SPE) silica gel cartridges, and then analyzed in GC/MS and LC/MS. The recovery percentages, obtained spiking the beverage samples at concentrations of 4 and 10 microgl(-1) with a standard mixture of photoinitiators, were in the range 42-108% (milk), 50-84% (wine), and 48-109% (fruit juices). The repeatability of the method was assessed in all cases by the % of correlation value, that was lower than 19%. The lowest limits of detection (LODs) and limits of quantification (LOQs), obtained using GC/MS, were in the range 0.2-1 and 1-5 microgl(-1), respectively. The method was applied to the analysis of forty packaged food beverages (milk, fruit juices and wine samples). The most significant contamination was that of benzophenone, found in all samples in a concentration range of 5-217mugl(-1). Its presence was confirmed by an LC/Atmospheric-Pressure PhotoIonization (APPI)/MS/MS analysis. The photoinitiator (EHDAB) was found in eleven out of forty beverages in a concentration range of 0.13-0.8 microgl(-1). Less important was the ITX contamination, found in three out of forty samples in a range 0.2-0.24 microgl(-1). The work proposes a new method to analyze ink photoinitiator residues in polycoupled carton packaging and in contained food beverages.     

Determination of sorbic acid in urine by gas chromatography-mass spectrometry.

The average daily uptake of the common food preservative sorbic acid is estimated to range from 0.01 to 1.1 mg kg-1. Sorbic acid mainly is metabolised to carbon dioxide. Minor amounts are converted to trans,trans-muconic acid (ttMA) as well as excreted unchanged into the urine. Since urinary ttMA is a biomarker for the occupational and environmental exposure to benzene, there is an additional need for monitoring the uptake of sorbic acid, particularly at low, environmental benzene exposure levels. For this purpose, a simple, robust and rapid method for the determination of sorbic acid in urine at trace levels was developed. After addition of 10 ml of water and 5 ml of 8 M hydrochloric acid to 10 ml of the thawed urine, the sample was water steam distilled using an automated distillation device. A total of 100 ml of the distillate were solid-phase extracted. After washing, the sorbic acid was eluted with 4 ml methanol. The eluate was reduced under a stream of nitrogen to a volume of 300 microliters. After addition of 500 microliters boron trifluoride in methanol and incubation for 1 h at 60 degrees C, the resulting sorbic acid methyl ester was extracted three times with 1 ml heptane. To the combined heptane layers, sorbic acid ethyl ester was added as an internal standard. After reducing to a volume of 100 microliters in a stream of nitrogen, the final analysis was performed by GC-MS using the fragment ions m/z 126 for the analyte and m/z 140 for the internal standard. The limit of detection was 0.7 ng ml-1 urine and the R.S.D. of 69 duplicate determinations was 7.5%. In a controlled, experimental study and in a field study, we were able to show that urinary sorbic acid is a marker for the dietary uptake of sorbic acid and that sorbic acid is converted to ttMA. On average, 0.1% of the dietary sorbic acid is excreted unchanged into the urine. Excretion is complete within 24 h. We found that, on average, 0.23% of the oral dose of sorbic acid is excreted as urinary ttMA. There was a significant correlation between urinary excretions of sorbic acid and ttMA (r = 0.74, n = 69). We conclude that urinary sorbic acid can be used to correct the urinary ttMA level in order to determine the portion related to benzene exposure. This appears to be necessary particularly at low, environmental benzene levels.     

Determination of fipronil by solid-phase microextraction and gas chromatography-mass spectrometry.

A method for the determination of trace amounts of the insecticide fipronil was developed using solid-phase microextraction-gas chromatography-mass spectrometry and selected ion monitoring. Fipronil was extracted with a fused-silica fiber coated with 85 microm polyacrylate. The effects of pH, ionic strength, sample volume, extraction and desorption times as well as the extraction temperature were studied. Lindane was used as an internal standard. The linear concentration range of application was 0.3-100 ng ml(-1) of fipronil, with a relative standard deviation of 9.5% (for a level of 50 ng ml(-1)) and a detection limit of 0.08 ng ml(-1). The method was applied to check the eventual existence of fipronil above this limit in water and soil samples from Granada (Spain) as well as in human urine samples. The method validation was completed with spiked matrix samples. The method can be applied as a monitoring tool for water, soil and urine, in the investigation of environmental and occupational exposure to fipronil.     

GC-MS直接测定芥酸酰胺

通常衍生后的酰胺才能用气相色谱测定.在实验几种酰胺衍生化方法时发现衍生反应不彻底剩余的芥酸酰胺也能出峰.进一步实验表明:芥酸酰胺在295 ℃气化后可直接测定,该法以邻苯二甲酸二丁酯为内标,质量浓度在115.4～923.2 mg/L 范围内线性关系良好,样品回收率94.85%～98.04%,芥酸酰胺的检出限5.77 mg/L.     

Clinical applications of gas chromatography and gas chromatography-mass spectrometry of steroids.

This review article underlines the importance of gas chromatography-mass spectrometry (GC-MS) for determination of steroids in man. The use of steroids labelled with stable isotopes as internal standard and subsequent analysis by GC-MS yields up to now the only reliable measurement of steroids in serum. Isotope dilution GC-MS is the reference method for evaluation of routine analysis of serum steroid hormones. GC-MS is an important tool for detection of steroid hormone doping and combined with a combustion furnace and an isotope ratio mass spectrometer the misuse of testosterone by athletes can be discovered. Finally the so called urinary steroid profile by GC and GC-MS is the method of choice for detection of steroid metabolites in health and disease.     

气相色谱-质谱法测定水中痕量的四乙基铅

建立了气相色谱-质谱(GC-MS)测定水中痕量四乙基铅的分析方法。用正己烷萃取水样中的四乙基铅,萃取液浓缩后加入同位素内标萘-d8,采用GC-MS选择离子方式(SIM)进行检测,在200 mL水样中四乙基铅的检出限可达0.04 μg/L;添加回收率为92.2%～103%,准确度好;平行5次测定的相对标准差为4.4%～13.3%。结果表明: 方法简便、快速、准确、实用,可用于水中痕量四乙基铅的测定。     

气相色谱-质谱法检测涂料中的六溴环十二烷

建立了防火涂料中阻燃剂六溴环十二烷(HBCD)的气相色谱-质谱(GC-MS)分析方法。样品用二氯甲烷进行萃取,萃取液经有机滤膜过滤后,用气相色谱-质谱联用仪进行测定。在选择离子检测模式下以m/z 157、239、319、401为定性离子,m/z 239为定量离子进行结构确证和定量检测。在优化的实验条件下,六溴环十二烷标准溶液在5~100 mg/L的质量浓度范围内线性关系良好,相关系数大于0.999。对市售的空白丙烯酸树脂涂料样品及环氧树脂涂料样品进行加标回收试验,结果表明本方法的平均回收率为92.9%~116.3%, RSD不超过8%。方法的检出限(S/N=3)为30 μg/g,定量限(S/N=10)为100 μg/g。本方法简便、快速、准确性好、精密度高,能够满足检测工作的实际要求。     

气相色谱-质谱法测定化妆品中的三氯叔丁醇

建立了测定化妆品中三氯叔丁醇的气相色谱-质谱分析方法.膏霜、水剂、散粉、香波、唇膏等不同类型的化妆品样品加入50％甲醇-无水乙醇或无水乙醇超声提取后,样品提取液高速离心处理,取上清液经无水硫酸钠脱水,进行气相色谱-质谱定性及定量分析.选用DB-1701(30 m×0.25 mm×0.25μm)石英毛细管柱,程序升温,流...     

Determination of zopiclone in urine by gas chromatography-mass spectrometry

A procedure is described for the quantitative determination of zopiclone and the sum of its metabolites in urine using gas chromatography with the mass-spectrometric detection of their common hydrolysis product, 6-(5-chloro-2-pyridyl)-7-hydroxy-6,7-dihydro-5H-pyrrolo[3,4-b]pyrazine-5-on. The procedure is very sensitive. The detection limit for ions with a mass of 45–450 au detected in the full scanning mode is 70 ng/mL. The data of gas chromatography-mass spectrometry are presented for different derivatives of the hydrolysis product of zopiclone; these data can be used for the qualitative identification of zopiclone. The stability of zopiclone and its metabolites upon time was studied by analyzing urine samples from patients receiving therapeutic doses of this substance stored for 1, 3, and 6 months.     

Determination of selenoamino acids by gas chromatography-mass spectrometry

The application of the recently introduced ethylchloroformate derivatization method for the separation and determination of selenomethionine and selenocystein in selenium-enriched yeast and yeast-free tablets by means of a gas chromatography-mass spectrometry (GC-MS) system has been studied. The efficiency of three methods for the extraction of selenomethionine from the tablets were compared. Total selenium content of the same tablets were measured using inductively coupled plasma (ICP)-MS and it was found that in the selenized yeast tablets about 80% of the total selenium is present as selenomethionine. The results were in agreement with the values in the labels and with the literature. The accuracy of the total selenium analysis was controlled by the analysis of a reference material.     

蜂蜜中氯霉素残留的气质分析方法研究

氯霉素(chloramphenicol)又名左旋霉素,是一类广谱抗生素,作为药物常用于家禽疾病治疗和预防.氯霉素对人的造血系统、消化系统具有严重的毒性反应,有可能引发人的再生障碍性贫血.因此欧盟等国家规定蜂蜜及其它动物源食品中氯霉素的最高残留量不得超过0.1μg/kg.本文对蜂蜜样品的提取、净化和富集方法进行了较为系统地研究,建立了固相萃取-气相色谱-质谱联机分析蜂蜜中的氯霉素残留量的方法.对氯霉素在固相萃取柱上的保留行为进行了研究,优化固相萃取条件,发现在选定的条件下,不同浓度的氯霉素在硅胶柱和C18柱上的回收率均在90%以上,蜂蜜加标的回收率在80%～95%,相对标准偏差在7.2%～18.2%,最低检出限为0.1μg/kg.对氯霉素的三甲基硅烷化衍生物采用选择离子的模式进行检测(376,378,466、468、470),衍生物的峰面积与样品浓度在0.55～220 ng/mL范围内呈良好的线性关系,线性回归系数为0.9998.     

气相色谱-质谱联用法测定紫菜中扑草净的残留量

建立了固相萃取净化与气相色谱-质谱联用技术测定紫菜中扑草净除草剂残留量的检测方法。样品由乙腈溶剂提取浓缩后,活性炭和氨基柱双柱串联固相萃取净化,由气相色谱-质谱联用技术测定。方法定量限为2μg/kg,满足国外最低10μg/kg的限量要求;方法在10,40和100μg/kg 3个添加水平和不同人员操作条件下,回收率均稳定在90%~120%之间,RSD%≤7.1%。