Headspace solid‐phase microextraction analysis of volatile compounds from spice essential oils in dry flavourings

The composition of volatile compounds in nine spices was analysed by means of headspace solid‐phase microextraction (HS‐SPME) from dry flavourings of the spice essential oils, to devise an effective method to determine the content of the essential oils. The HS‐SPME was combined with GC‐MS and GC‐FID for identification and quantification of the volatile compounds. The optimisation of the extraction conditions was carried out by response surface methodology. The evaluation of the analytical parameters indicated that the method had a high precision (coefficient of variations lower than 3%), it was linear (response factors were smaller than 5%) and recoveries were higher than 89%. In the ruggedness test, sample quantity and pre‐extraction time were the factors that stood out as the causing of the greater effects on the analytical results.     

Smoke and liquid smoke. Study of an aqueous smoke flavouring from the aromatic plant Thymus vulgaris L

An aqueous smoke flavouring from Thymus vulgaris L was obtained. The qualitative and quantitative composition of its dichloromethane extract was studied by gas chromatography and gas chromatography/mass spectrometry. In addition to the common smoke components such as aldehydes, ketones, diketones, esters, acids, furan and pyran derivatives, alkyl aryl ethers, phenol, guaiacol and syringol derivatives, some terpenic compounds were detected. Differences between this aqueous liquid smoke and others from various kinds of wood are due not only to the absence or presence of some compounds but also to the proportions of the different groups of components present in the mixture. Some aldehydes, esters, guaiacol and its derivatives and terpenic compounds contribute to the overall odour of this liquid smoke more significantly than the ketones, furan and pyran derivatives, acids, phenol and its derivatives and syringol. The yield in smoke components obtained from the pyrolysis of Thymus vulgaris L at 488 °C is of a similar order to that obtained from other woods. © 1999 Society of Chemical Industry     

气相色谱/质谱联用测定纺织品中5种苯酚类化合物

探讨了气相色谱/质谱(GC/MS)联用测定纺织品中4种含氯酚及邻苯基苯酚残留量的方法.样品经甲醇超声提取、浓缩后,用0.1 mol/L的硼砂溶液溶解,再经乙酸酐乙酰化后用正己烷提取,GC/MS测定,外标法定量.在0.05~2.5 mg/L,方法的线性关系良好,相关系数为0.999 0~0.999 5,加标回收率为89%~105%,相对标准偏差为1.46%~5.32%.该方法简便、快速、灵敏度高,完全可满足进出口纺织品中4种含氯酚及邻苯基苯酚残留量检测的要求.     

山楂红酒香气成分的GC/MS分析

利用溶剂萃取法对山楂红酒中的香气成分进行提取,采用气相色谱-质谱(GC/MS)技术对其进行分析.结果表明,在山楂红酒中共分离出73个峰,鉴定出37种化合物;酯类和醇类是山楂红酒中香气组成最复杂的两类化合物,其中主要成分为丁二酸乙酯、苯乙醇、丁二酸二乙酯、甲氧基乙酸乙酯、酒石酸二乙酯、2,3-丁二醇、乳酸乙酯、对羟基苯乙醇、棕榈酸甲酯、4-羟基丁酸内酯.     

固相萃取-气相色谱-质谱联用法测定啤酒大麦中抗蚜威、乙草胺、三唑酮的残留量

研究了气相色谱/质谱法测定啤酒大麦中杀虫剂抗蚜威、除草剂乙草胺、杀菌剂三唑酮3种农药残留的分析检测方法。样品以丙酮作为提取剂,采用超声波清洗器和旋涡混合器混合提取啤酒大麦中的农药残留,经500mg、3mL SupelcleanTML C-18固相萃取柱净化。同时采用SIM的扫描模式,有效地去除了一些杂质的干扰,提高了分析的选择性。该方法的添加回收率在88%～106%,相对偏差小于5.61%,检测限0.010～0.020μg/kg,可相对快捷地检测啤酒大麦中抗蚜威、乙草胺、三唑酮。     

柱上衍生气相色谱/质谱法测定纺织品中PFOS

全氟辛基磺酸(PFOS)很难通过常规方法从纺织品中分离、检出.采用超声-微波协同萃取仪提取样品中的PFOS,以四丁基氢氧化铵(TBAH)为衍生化试剂,与PFOS形成铵盐,再在柱上进行衍生化反应,形成PFOS丁酯,进而被气相色谱/质谱(GC/MS)联用仪检出.通过探索最佳衍生化反应条件,确立了柱上衍生GC/MS的检测方法,并对实际纺织样品中PFOS进行分离、检测,结果显示样品中的PFOS含量在0.59～11.27 mg/kg之间,能够满足国际法规对纺织品中PFOS的限量检测要求.     

尾巨桉木片水抽提物成分的GC/MS分析

采用冷水浸渍法从新鲜尾巨桉木片中提取有效成分,经浓缩、干燥、苯-甲醇溶解后,再用气相色谱/质谱法(GC/MS)联机分析技术,用色谱峰面积归一化法计算各组分的相对含量。共分离出35个峰,结合文献调研,鉴定出12个化合物,占总峰面积的53.67%。主要成分为2,6,10,15,19,23-六甲基-鲨烯(18.04%)、2,4’,5-三甲基二苯甲烷(7.68%)、二十五(碳)烷(5.93%)、2,6,10,14-四甲基-十五烷(5.10%)、十九(碳)烷(4.95%)、2,6,10,14-四甲基-十六烷(3.97%)、5,6-二氢5,6-二甲基苯-邻二氮(杂)萘(2.80%)、7,3’,4’-三甲氧基-槲皮素(1.53%)、6,10,14-三甲基-2-十五烷(1.02%)等。     

UPLC-ESI-MS/MS analysis of Sudan dyes and Para Red in food

An analytical method for the simultaneous determination of Sudan dyes (Sudan Red G, Sudan I, Sudan II, Sudan III, Sudan Red 7B and Sudan IV) and Para Red in food by ultra-performance liquid chromatography-electrospray tandem mass spectrometry (UPLC-ESI-MS/MS) was developed. Samples were extracted with acetonitrile, and water added into the extract. The supernatant was analysed by UPLC-MS/MS after refrigeration and centrifugation. The sample was separated on an Acquity BEH C₁₈ column, and detected by MS/MS with the multiple reaction monitoring mode. Matrix calibration was used for quantitative testing of the method. The linear matrix calibrations of Sudan dyes and Para Red were 2–50 and 10–250 ng g^?1, respectively, and the regression coefficients were >0.9945. The recoveries were 83.4–112.3% with good coefficients of variation of 2.0–10.8%. The limits of detection were between 0.3 and 1.4 ng g^?1 for the six Sudan dyes, and between 3.7 and 6.0 ng g^?1 for Para Red. The limits of quantification were between 0.9 and 4.8 ng g^?1 for the six Sudan dyes, and between 12.2 and 19.8 ng g^?1 for Para Red.     

Quantitative determination of mycotoxins in urine by LC-MS/MS

Naturally occurring mycotoxins are responsible for a wide array of adverse health effects. The measurement of urinary mycotoxin levels is a useful means of assessing an individual's exposure, but the development of sensitive and accurate analytical methods for detecting mycotoxins and their metabolites in urine samples is challenging. Urinary mycotoxins are present in low pg ml^–1 concentrations, and the chromatographic identification of their metabolites can be obscured by other endogenous metabolites. We developed an analytical method focused on the selection of two appropriate multiple-reaction monitoring transition for unambiguous identification and quantification of carcinogenic aflatoxin M₁ (AFM₁), ochratoxin A (OTA) and fumonisin B₁, B₂ (FB₁, FB₂) in urine samples from a small volunteer group in a pilot study. AFM₁, OTA, FB₁ and FB₂ were concentrated selectively, interfering substances were removed using an immunoaffinity column (IAC), and mycotoxins were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in combination with a stable-isotope standard-dilution assay (SIDA). The method was sensitive enough to measure mycotoxins and their metabolites at pg ml^–1 levels in urine. The combination of LC-MS/MS and SIDA was critical to distinguishing pseudo-OTα interference from genuine OTα. Twelve urine samples contained OTA ranging from 0.013 to 0.093 ng ml^?1 (mean = 0.031 ng ml^?1). AFM₁ were detected in one sample at a 0.002 ng ml^?1 level, while FB₁ and FB₂ were undetectable in all 12 samples. None of the samples in this pilot study contained a detectable level of OTα, despite the presence of OTA, and this may suggest the need for further epidemiological investigation of OTA exposure in the Korean population.     

地毯有机挥发物的ETC-ATD-GC/MS联用测试法

采用环境测试舱(ETC)、自动热脱附仪(ATD)和气相色谱/质谱(GC/MS)联用技术,建立了地毯中13种挥发性有机物(VOCs)的分析方法。该方法对VOCs单体的最小检出限(LODs)范围为0.008～0.4μg/m~3,方法的加标回收率为90%～106%,相对标准偏差(RSD)小于11%。将该方法用于多种市售地毯的VOCs测试,发现地毯释放VOCs的种类,与地毯底层材料有较大关联,沥青底胶层的方块地毯释放出较多的2-乙基-1-己醇,黄麻背衬地毯和聚酯背衬地毯释放出较多的苯乙烯和4-苯基环己烯,而薄层聚丙烯背衬地毯则释放出较多的直链或支链烷烃。     

气相色谱-质谱法测定酱油中氯丙醇类化合物

建立了酱油中两种氯丙醇类化合物检测的气相色谱-质谱分析方法.样品中加入两种稳定性氘代同位素内标,经基质固相分散萃取(MSPD)分步提取、净化,七氟丁酰基咪唑衍生化后进行GC/MS测定.两种氯丙醇化合物的线性范围均为10～1600 ng,检出限为5μg/kg;回收率为99.5%～110%,RSD%为3.8%～6.6%.该方法测定灵敏度高,定性准确,选择性好,稳定性高,适合于样品中多种痕量氯丙醇类化合物的同时测定.     

微波辅助顶空固相微萃取法分析新疆洋葱籽挥发性成分

采用微波辅助萃取与顶空固相微萃取联合的方法萃取新疆洋葱籽挥发性成分,并用气相色谱-质谱联用技术分析对新疆洋葱籽中的挥发性成分进行了鉴定,共分离出50种成分,确认了其中的42种成分,占挥发性成分的95.46%。采用面积归一法确定各成分的相对百分含量,其中主要为萜类化合物及其衍生物。     

Development of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of glucocorticoid residues in edible tissues of swine,cattle, sheep,and chicken

A confirmatory and quantitative method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine the presence of eight glucocorticoids (prednisone, prednisolone, hydrocortisone, methylprednisolone, dexamethasone, betamethasone, beclomethasone, and fludrocortisone) in the muscles and livers of swine, cattle, and sheep and the muscle of chicken is described. After deconjugation in alkali media, samples were extracted with ethyl acetate for glucocorticoids followed by solid-phase extraction clean-up and reconstitution in the LC mobile phase. The hydrolysis procedure with sodium hydroxide was used to reduce handling time. A single-step solid-phase extraction method was optimized which is suitable for the clean-up of the compounds of interest in many diverse tissue matrices. LC separations were performed on a C₁₈ column with gradient elution using acetonitrile and water (containing 0.2% formic acid) and the two epimers betamethasone and dexamethasone were successfully separated. LC-electrospray ionization (ESI)-MS/MS in negative mode with selected reaction monitoring (SRM) mode was performed to improve method sensitivity and reduce matrix interference. Two SRM transitions were used for each compound. The recovery of glucocorticoids spiked at levels of 0.5–16 µg kg^?1 ranged from 55% to 107%; the between-day relative standard deviations were no more than 15%. The limits of quantification were 0.5–2.0 µg kg^?1 in muscle and 1–4 µg kg^?1 in liver. The optimized procedure was successfully applied to monitor the food at the 2008 Summer Olympics Games in Beijing, China, demonstrating the method to be simple, fast, robust, and suitable for identification and quantification of glucocorticoids residues in foods of animal origin.     

固相微萃取-气相色谱/质谱联用技术分析茉莉精油化学成分

采用固相微萃取、气相色谱 -质谱联用技术分析了茉莉精油的化学成分 ,共分离、鉴定了 4 1种化学物质 ,占其挥发性成分的 99.4 3%。结果表明 ,茉莉精油中的主要成分为 :芳樟醇、苯甲基乙酸酯、N ,N -二丙基苯甲酰氨及α -金合欢烯等。     

Development of a novel solid-phase extraction,LC-MS/MS method for the analysis of ethyl carbamate in alcoholic beverages: application to South African wine and spirits

Ethyl carbamate (EC) is a known genotoxic carcinogen that is frequently present in alcoholic beverages and is therefore a public health concern. As a consequence, maximum concentration levels for EC in these commodities are legislated in several countries. Quantitative analytical methods are therefore essential to monitor EC levels in beverages. Most published analytical methods for the determination of EC in alcoholic beverages utilise elaborate sample pre-treatment procedures to obtain injectable samples, or yield low sensitivity, for example where direct injection is used. In addition, these procedures often require large volumes of toxic solvents and are not generally applicable to diverse alcoholic beverages. This paper describes a novel procedure for the determination of EC in wines, fortified wines and spirits. The procedure is based on reversed-phase solid-phase extraction (SPE) sample clean-up combined with normal-phase liquid chromatography-atmospheric pressure chemical ionisation tandem mass spectrometric (NP-LC-APCI-MS/MS) analysis. This method provides a rapid, robust and simple analytical procedure suitable for the analysis of a diverse range of alcoholic beverages. The accuracy of the method (expressed as average recovery from diverse matrices) is 94.5%, with limits of detection (LODs) ranging between 0.25 and 0.63?µg?l^?1 for different matrices. Benefits such as simplified sample preparation, low detection limits, low solvent consumption and good selectivity render the methodology ideally suited to study the occurrence of EC in diverse commodities. The method was applied to study the occurrence of EC in South African wines, fortified wines and spirits. South African wines, aged 1–9 years, contained 1.8–31?µg?l^?1 EC (RSD?=?69%, n?=?106), fortified wines aged 2–34 years contained 2.8–79?µg?l^?1 EC (RSD?=?89%, n?=?21), and brandies aged 3–20 years contained 4.4–95?µg?l^?1 EC (RSD?=?105%, n?=?26). Factors affecting the formation of EC in these commodities were investigated and storage temperature, alcohol content and pH were found to affect the rate of EC formation. Of these variables storage temperature has by far the greatest effect.     

气质联用-选择离子扫描测定卷烟主流烟气中糠醛的含量

利用超声波溶剂提取减压蒸馏对样品进行前处理,基于气质联用,采用全扫描与选择离子扫描相结合,同时测定卷烟主流烟气中糠醛、5-甲基糠醛的含量。主要对云南两地烟叶不同部位两种糠醛进行测定,测定结果表明,昆明红大下部烟叶以及玉溪1云上部烟叶中主流烟气中糠醛含量较其他烟叶相比含量较高。研究了分析标准曲线、精准度、回收率以及不同种类烟草样品中两种物质的含量差别。结果表明,所设定的实验条件下,由于选择定性定量离子的不同,二者之间定量没有干扰,相关系数为0.9995～0.9997,加标回收率为92%～96%,相对标准偏差RSD均小于4%。     

GC/MS characterisation of cyclodimers from p-coumaric and ferulic acids by photodimerisation—a possible factor influencing cell wall biodegradability

The cyclodimerisation of trans-p-coumaric (tCA; (E)-3-(4-hydroxyphenyl) propenoic acid) and trans-ferulic (tFA; (E)-3-(4-hydroxy-3-methoxyphenyl) propenoic acid) acids to form substituted truxillic and truxinic acids has been investigated since dimers of this type are present in graminaceous cell waits and are likely to be of importance in limiting wall biodegradability. Irradiation of a thin film of a mixture of tCA and tF A, under ‘daylight’ fluorescent tubes and incandescent lamps in a growth cabinet, produced three cyclodimers corresponding to 16 % conversion of monomers. Under the same conditions of irradiation, a thin film of FA alone yielded only 2% of F A-F A. When tF A crystals were irradiated, no dimerisation occurred, whereas tCA crystals were totally dimerised to CA-CA. Lower yields of dimers were obtained using UV irradiation. The dimers were shown, by capillary gas-liquid chromatography and mass spectrometry, to be derivatives of truxillic acid (t-2, c-4-diphenyl-r-1, t-3-cyclobutanedicarboxylic acid) composed of CA-CA, CA-FA and FA-FA, and to have gas chromatographic retention times identical to those of dimeric compounds found in grass cell walls. The results are considered in relation to dimerisation of phenolic acids in plant cell walls under the influence of sunlight.     

A robust GC-MS/MS method for the determination of chlorothalonil in fruits and vegetables

Chlorothalonil is a non-systemic fungicide that is easily degraded in contact with plants and soil or even by the effect of light and pH. A method for the determination of chlorothalonil in courgettes, strawberries, oranges, leeks and tomato by solvent extraction followed by GC-MS/MS with a triple quadrupole analyser was developed. The causes of chlorothalonil degradation during sample treatment were studied and minimised. The final method was based on extraction with acetone in the presence of 0.1?M EDTA sodium salt solution, and clean-up by SPE using OASIS HLB cartridges. Isotope-labelled hexachlorobenzene (HCB-¹³C₆) was added as an internal standard to the SPE extracts before analysis by GC-MS/MS (EI) (QqQ) analysis in order to correct for instrumental deviations. Quantification was performed by matrix-matched standard calibration using relative responses to the internal standard. Two MS/MS transitions were used for mass spectrometric determination of chlorothalonil to ensure reliable quantification and confirmation. The method was validated using blank samples (for all matrices) spiked at two levels. Recoveries between 77% and 110% and an RSD below 20% were obtained for 0.1 and 0.01?mg?kg^?1 spiking levels (n?=?5). The validated method was applied to treated and untreated samples collected from an experimental field where a chlorothalonil formulated was applied.     

UNE-EN ISO/IEC 17025:2005-accredited method for the determination of pesticide residues in fruit and vegetable samples by LC-MS/MS

A rapid, simple and sensitive multi-residue method was developed and validated for the simultaneous quantification and confirmation of 69 pesticides in fruit and vegetables using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted following the quick, easy, cheap, effective, rugged and safe method known as QuEChERS. Mass spectrometric conditions were individually optimised for each analyte in order to achieve maximum sensitivity in multiple reaction monitoring (MRM) mode. Using the developed chromatographic conditions, 69 pesticides can be separated in less than 17 min. Two selected reaction monitoring (SRM) assays were used for each pesticide to obtain simultaneous quantification and identification in one run. With this method in SRM mode, more than 150 pesticides can be analysed and quantified, but their confirmation is not possible in all cases according to the European regulations on pesticide residues. Nine common representative matrices (zucchini, melon, cucumber, watermelon, tomato, garlic, eggplant, lettuce and pepper) were selected to investigate the effect of different matrices on recovery and precision. Mean recoveries ranged from 70% to 120%, with relative standard deviations (RSDs) lower than 20% for all the pesticides. The proposed method was applied to the analysis of more than 2000 vegetable samples from the extensive greenhouse cultivation in the province of Almería, Spain, during one year. The methodology combines the advantages of both QuEChERS and LC-MS/MS producing a very rapid, sensitive, accurate and reliable procedure that can be applied in routine analytical laboratories. The method was validated and accredited according to UNE-EN-ISO/IEC 17025:2005 international standard (accreditation number 278/LE1027).     

Detection of endogenous steroid abuse in cattle: results from population studies in the UK

The use of steroids as growth-promoting agents in food production is banned under European Union legislation. Detecting the abuse of testosterone, nandrolone, boldenone, oestradiol and progesterone is complicated by the fact that these steroids are known to be endogenous in certain situations. In this study, the concentrations of characteristic metabolites of each of these steroids were quantified in populations of untreated steers and heifers. Steroid concentration population data were then used by a statistical model (the Chebyshev inequality) to produce threshold concentrations for screening and confirming the abuse of these steroids in steer and non-pregnant heifer urine. In addition to thresholds based on testing one animal (a ‘1 out of 1’ approach), new methods based on testing multiple animals from a herd (a ‘y out of n’ approach) allowed threshold concentrations to be significantly reduced and hence false compliances to be minimised. In the majority of cases, the suggested thresholds were found to be capable of confirming the abuse of endogenous steroids in steers and heifers. In the case of oestradiol abuse in the female, however, confirmation based on a threshold is not possible and alternative methods such as gas chromatography-combustion-isotope ratio mass spectrometry are required. In addition to the steer and heifer populations, a small number of pregnant animals were also tested, yielding insights into the biosynthetic pathways of some of the steroids.