Determination of pyrethroid metabolites in human urine by capillary gas chromatography-mass spectrometry

Summary An analytical method for the simultaneous determination of the pyrethroid metabolites cis and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid, cis 3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid, 3-phenoxybenzoic acid and 4-fluoro-3-phenoxybenzoic acid in human urine samples is described. The urine is subjected to acid-induced hydrolysis followed by exhaustive solvent extraction, covering both conjugated and free acids, followed by a common derivatisation step yielding the corresponding methyl esters. Quantitation was by diastereomeric, capillary gas chromatography-mass spectrometry. It appears that 4-fluoro-3-phenoxybenzoic acid is a characteristic urinary marker for cyfluthrin exposure. The limits of determination are 0.5–1.0 g L^–1 urine depending on the metabolites concerned. The applicability of the method was tested on urine samples from pest control operators exposed occupationally to cypermethrin and cyfluthrin.     

化妆品及香精中27种香料的气相色谱-质谱检测方法

建立了气相色谱-质谱同时检测化妆品及香精中27种香料的方法。采用甲醇作为提取溶剂，经弱极性毛细管柱分离，用气相色谱-质谱检测，离子源为电子轰击离子（EI）源。该方法对麝香二甲苯、羟基香茅醛和羟异己基3-环己烯基甲醛的检出限分别为1.2、15和15 mg/kg，其余香料的检出限为3.0 mg/kg。27种香料在相应的线性范围内线性关系良好，相关系数均大于等于0.996。在3个加标浓度下，麝香二甲苯的回收率为73.3%~76.1%，其余为81.5%~118%，相对标准偏差小于10%。采用建立的方法对69份香精或标示含香料化妆品进行检测，全部样品都检测出含有一种或多种香料。该方法适用于化妆品及香精中27种香料的测定。     

土壤中烃类污染物的超临界流体萃取

采用超临界流体萃取技术提取环境样品中的烃类污染物，以色谱－质谱联用仪测定了萃取物的化学成分，考察了影响萃取效率的主要因素。比传统的索氏萃取能更有效地从复杂环境样品中萃取分析物。     

高效液相色谱-串联质谱法测定小鼠组织中的新型抗心力衰竭化合物AF-HF001

建立了基于高效液相色谱-质谱联用技术的新型抗心力衰竭化合物AF-HF001在小鼠组织中的测定方法,并考察了其在小鼠体内的组织分布。采用液-液萃取对样品进行预处理,以Thermo Hypersil Gold C18色谱柱进行分离,流动相为乙腈-0.1%甲酸水溶液,梯度洗脱,采用选择性反应监测(SRM)正离子模式检测分析物。小鼠组织中AF-HF001含量在0.5~10μg/mL范围内线性关系良好(r>0.996),在加标量为1.5,4,10μg/mL的组织样品中,提取回收率大于58%,基质效应在100.38%~109.99%之间,日内和日间精密度RSD均小于15%。该方法为AF-HF001的体内分布研究及进一步药物研发提供了依据。初步结果表明,该化合物能够迅速到达心脏并迅速代谢,主要分布在肝脏组织中,其他组织中分布较少。     

Identification and quantification of 13 components in Angelica sinensis (Danggui) by gas chromatography-mass spectrometry coupled with pressurized liquid extraction

Angelica sinensis (Danggui in Chinese), a well-known traditional Chinese medicine, is also used as a health food product for women's care in Europe and America. Therefore, the demand for Danggui is enormous throughout the world. Due to the shortage of Angelica sinensis, Angelica acutiloba and Angelica gigas are commonly used as the substitutes of Danggui in the market of southeast Asia. However, the three common Angelica roots showed variation in their genetic and chemical composition. Up to date, it is thought that ferulic acid, ligustilide and other phthalides such as butylidenephthalide are the biologically active components of Danggui. In this paper, the contents of 13 compounds including ferulic acid, Z-ligustilide, E-ligustilide, Z-butylidenephthalide, E-butylidenephthalide, 3-butylphthalide, 3-butylidene-4-hydroxyphthalide, senkyunolide A, 6,7-epoxyligustilide, senkyunolide F, senkyunolide H, senkyunolide I, and 6,7-dihydroxyligustilide were determined or estimated by using gas chromatography-mass spectrometry (GC-MS) coupled with pressurized liquid extraction (PLE). The results showed that GC-MS coupled with PLE offered a simple, rapid and high sensitive method to analysis of components in Angelica root. And the contents of investigated compounds in Angelica sinensis, Angelica acutiloba and Angelica gigas, which are used as Danggui in China, Japan and Korea, respectively, were highly variant. It is thought that interaction of multiple chemical compounds contributes to the therapeutic effects of Chinese medicines. However, the overall clinical efficacy of these different Danggui has not been determined. Therefore, comparison of chemical components and pharmacological activities of different Angelica root is helpful to elucidate the mechanism of therapeutic effects of Danggui.     

A Large Volume Injection Procedure for GC-MS Determination of PAHs and PCBs

A simple on-column injection system for large volume of liquid samples for the GC-MS determination of traces of PAHs and PCBs has been investigated. A deactivated fused silica capillary 20 m × 0.53 mm I.D. and 2 meters of an HP5 column (0.53 mm,1 m film thickness) were used as retention gaps. Injection volumes of 80 L for PAHs and 90 L for PCBs, allow determination of 5–50 ng L^–1 PAHs and 11–44 ng L^–1 PCBs in hexane solution with an RSD of < 10%. The method has been used for the determination of PCBs and PAHs in soil sample.     

Direct capillary gas chromatographic analysis and thermal stability of bile acid esters of glucose

Summary This paper deals for the first time with a direct method for analysis of the α and β anomers of bile acid esters of glucose by capillary gas chromatography (CGC) without the need for a hydrolytic step. The bile acid esters were derivatized to their trimethylsilyl (TMS) ethers, which in turn were chromatographed on a short (7m) metal capillary column chemically coated with a thin (0.15 μm) film of thermostable, non-polar polydimethylsiloxane. Satisfactory CGC separation of the isomeric bile acid esters was achieved on the column; the β anomers eluted before the corresponding α isomers. Particularly noteworthy is that the α anomers are partially isomerized to the corresponding β anomers, and that both anomers are partially decomposed during CGC analysis, demonstrating the chemical specificity and thermal instability of the bile acid esters.     

Study on the Tautomer Interconversion of 3-Oxo Pentanoate During Gas Chromatography

Enol and keto tautomers of methyl 3-oxo pentanoate could be separated on a HP-5 capillary column. The chromatographic peaks were identified by examining characteristic mass ions arose from the corresponding enol and keto molecular ions. The study showed that the area percentage of enol tautomer is a function of temperature of the column. Treating the column as a reactor, the energy of activation for the on-column tautomerization could be extracted (35.1 kJ mol⁻¹) by monitoring the loss of the enol tautomer, because the reaction is found to obey pseudo first-order kinetics. The enthalpy and the entropy changes (ΔH = −3.98 kJ mol⁻¹, ΔS = −7.89 J K⁻¹mol⁻¹) for the enol-to-keto reaction in the stationary phase were also obtained.     

Degradation-fragmentation of marine plastic waste and their environmental implications: A critical review

This review critically evaluates the plastic accumulation challenges and their environmental (primarily) and human (secondarily) impacts. It also emphasizes on their degradation and fragmentation phenomena under marine conditions. In addition, it takes into account the leachability of the various chemical substances (additives) embedded in plastic products to improve their polymeric properties and extend their life. Regardless of their effectiveness in enhancing the polymeric function of plastic products, these additives can potentially contaminate air, soil, food, and water. Several findings have shown that, regardless of their types and sizes, plastics can be degraded and/or fragmented under marine conditions. Therefore, the estimation of fragmentation and degradation rates via a reliable developed model is required to better understand the marine environmental status. The main parameter, which is responsible for initiating the fragmentation of plastics, is sunlight/UV radiation. Yet, UV- radiation alone is not enough to fragment some plastic polymer types under marine conditions, additional factors are needed such as mechanical abrasion. It should be also mentioned that most current studies on plastic degradation and fragmentation centered on the primary stages of degradation. Thus, further studies are needed to better understand these phenomena and to identify their fate and environmental effects.     

Determination of Hormones and Non-ionic Surfactant Degradation Products in Small-Volume Aqueous Samples from Soil Columns Using LC-ESI-MS-MS and GC-MS

The leaching of two estrogens, 17β-estradiol and estrone, and two degradation products of non-ionic surfactants, octylphenol and nonylphenol, through a soil column were studied to estimate their transport behavior. Different concentration methods (lyophilization, solid phase extraction, and liquid–liquid extraction) were evaluated for analyzing these compounds in small effluent fractions (30–50 mL) collected. Liquid chromatography-mass spectrometry (LC-MS-MS) and gas chromatography-mass spectrometry (GC-MS) were employed for quantitative analysis of these compounds. After comparison, the lyophilization-LC-MS-MS method was found to be best suited for the analysis of the two estrogen hormones and the liquid–liquid extraction-GC-MS method best for the analysis of the two phenols in small samples in the soil column study. Because of their high sorption capacity, these compounds were mostly sorbed in the upper part of the soil column and were difficult to detect in column effluent.