静态顶空气相色谱法测定有机残留溶剂二甲基亚砜

建立了高灵敏度、高精确度的静态顶空气相色谱结合氢火焰离子化检测器测定药物辅料中二甲基亚砜残留溶剂的方法.以液体石蜡为溶解溶剂,优化了顶空瓶的液相体积,并对顶空气相色谱的关键实验参数:自动进样时间、顶空加压时间、顶空平衡温度、顶空平衡时间及气相柱温箱升温程序等进行了优化.在最优条件下,确定了方法的检出限和定量限分别为1....     

顶空气相色谱法测定离子交换树脂中8种有机溶剂残留

建立了功能食品加工用离子交换树脂中甲基异丙基甲酮、丁酸甲酯、3-戊酮、1,3-二乙基苯、1,4-二乙基苯、1,2-二氯乙烷、间二氯苯、甲基丙烯酸甲酯8种有机残留物的顶空气相色谱检测方法,研究了不同类型树脂中的有机残留物种类及含量,为食品和药品中安全使用离子交换树脂提供依据.优化了样品的提取溶剂和顶空气相色谱条件,样品经...     

顶空气相色谱法测定制药工业污水中的甲苯

采用顶空气相色谱法测定制药工业污水中的甲苯含量.顶空瓶中的制药工业污水样品在顶空仪上加热平衡后,其顶空气体进入气相色谱仪中分离和检测.方法的检出限为0.002 mg/mL,测定结果的相对标准偏差为3.27%～9.26%(n=5),回收率为92.7%～97.0%.与GB/T 11890-1989相比,本方法操作简便快速、检测限低,具有较高的进样稳定性,结果计算更加科学准确.     

一种顶空气相色谱测定乳液聚合过程单体转化率的新方法

介绍了一种通过顶空气相色谱技术测定乳液聚合过程中单体转化率的新方法.通过对聚合乳液样品进行称量方式的采样和大比例的稀释,将已稀释的待测溶液移入顶空瓶中,在设定温度下达到气液平衡后进入气相色谱中测定,其消除了采样的波动性和顶空气相色谱测定的误差,并导出了由顶空气相色谱对样品中单体的测定信号直接计算聚合过程转化率的方程式.该方法具有实验操作简单、快速、检测准确等优点,非常适合乳液聚合反应动力学和机理的研究.     

全蒸发顶空气相色谱法测定聚乙烯醇中甲醇的含量

建立了全蒸发顶空气相色谱法测定聚乙烯醇中甲醇含量的方法. 采用固定相为100%的二甲基聚硅氧烷石英毛细管柱,以氮气为载气,流速为1.0 mL/min,分流比为1:100,检测器温度为200 ℃,进样口温度为150 ℃,顶空进样,平衡温度为120 ℃,平衡时间为90 min,相关系数r为0.9979. 在此色谱条件下被测物均能得到很好的分离,甲醇峰面积与检测浓度呈良好的线性关系. 方法的检测限为0.011 mg,回收率为98.15%. 采用改变气固相比的方法测定了顶空色谱下的气固相分配系数,在0.02~0.4之间,方法符合全蒸发顶空气相色谱法应用条件. 实验建立的色谱方法灵敏、准确、简单、方便、高效. 方法可同时对9个样品进行测定,适合于企业大批量聚乙烯醇中甲醇含量的测定.     

顶空气相色谱标准加入法测定自来水中的一溴二氯甲烷和二溴一氯甲烷

用于测定水中三卤甲烷的方法主要有吹扫捕集热解吸法和液液萃取法,固相微萃取技术与顶空法相结合也被应用于测定水中的挥发性卤代烃。我国水和废水标准方法规定用静态顶空外标方法测定三卤甲烷。作者曾报道了改变相比／顶空色谱法测定水中氯仿及其分配常数的方法。本文主要研究顶空气相色谱标准加入法测定城市自来水中的一溴二氯甲烷和二溴一氯甲烷。与顶空气相色谱外标法比较,该法避免了水样基体及色谱条件对测定结果的影响。与顶空气相色谱内标法比较,该法不用另外选择内标物,操作方便。     

改变相比/顶空气相色谱法测定水中苯的分配常数及其含量

推导了改变气液相比/顶空气相色谱法测定水中苯的分配常数及其含量的基本关系式。采用全挥发技术制备气体标样测定校正因子。通过测定3个不同相比的顶空浓度,计算顶空浓度倒数与相比之间的线性回归方程,测定了23 ℃时苯在纯水中的分配常数为5.878(亨利常数为0.170),与文献值的误差为5.22%。实际测定水样中苯的质量浓度为0.348 mg/L,与配制值0.357 mg/L的相对误差为2.52%。方法检出限可达3.5×10-3 mg/L。     

改变相比/顶空气相色谱法测定变压器油中溶解气体的分配常数

采用改变相比/顶空气相色谱法测定了甲烷、乙炔、乙烯、乙烷和丙烷在变压器油中的分配常数。顶空瓶中的气体样品经石英毛细管送到气相色谱仪的六通进样阀样品管中,然后进行分离和定量。采用标准曲线法定量,通过测定5个不同相比时轻烃组分的顶空浓度,计算顶空浓度倒数与相比之间的线性回归方程,测定了20 ℃和50 ℃时烃类气体在变压器油中溶解气体的分配常数。除甲烷外,计算所得的分配常数与文献值基本吻合,油中溶解气体浓度的实验值与实际值之间的相对误差小于4.14%,表明用此方法可以测定不同温度下变压器油中溶解气体的分     

顶空气相色谱法测定杏脯中二氧化硫

建立顶空气相色谱测定杏脯中二氧化硫残留的方法,探讨了气液体积比、加酸量、平衡温度和平衡时间对检测结果的影响。向450 mL顶空瓶内加入5 g样品、10 g石蜡、200 mL水及25 mL盐酸溶液,于75℃平衡20 min后放至室温,抽取0.5 mL顶空气体进行定性定量分析检测。该方法标准工作曲线线性相关系数r~2为0.992,检出限和定量限分别为0.1,1.0 mg/kg,测定结果的相对标准偏差为1.9%~3.2%(n=6),样品加标回收率为89.4%~94.3%。该法操作简便、快捷,灵敏度高,人为误差小,满足杏脯中二氧化硫残留的批量检测要求。     

气相色谱法同时测定塑料食品包装袋中4种有机残留物

食品塑料包装袋中的有机残留物甲苯是一种对人体有害的化合物.包装食品用的塑料制品.其含量为卫生和食品监督部门所严格控制.其中的异丙醇、丁酮和乙酸乙酯虽毒性不大,但它们的大量使用以及在环境中的行为不甚明了,因此建立一种同时测定4种组分的分析方法是十分必要的.有关顶空气相色谱法同时测定食品塑料包装袋中的4种残留组分的研究还未见报道.本文研究了一种简便、快速、准确的静态顶空气相色谱法,可同时测定塑料食品包装袋中的甲苯、异丙醇、丁酮和乙酸乙酯.该法操作简便,灵敏度高,重现性好,结果令人满意.     

Determination of partition behavior of organic surrogates between paperboard packaging materials and air

The suitability of recycled paperboard packaging materials for direct food contact applications is a major area of investigation. Chemical contaminants (surrogates) partitioning between recycled paper packaging and foods may affect the safety and health of the consumer. The partition behavior of all possible organic compounds between cardboards and individual foodstuffs is difficult and too time consuming for being fully investigated. Therefore it may be more efficient to determine these partition coefficients indirectly through experimental determination of the partitioning behavior between cardboard samples and air. In this work, the behavior of organic pollutants present in a set of two paper and board samples intended to be in contact with foods was studied. Adsorption isotherms have been plotted and partition coefficients between paper and air have been calculated as a basis for the estimation of their migration potential into food. Values of partition coefficients (Kpaper/air) from 47 to 1207 were obtained at different temperatures. For the less volatile surrogates such as dibutyl phthalate and methyl stearate higher Kpaper/air values were obtained. The adsorption curves showed that the more volatile substances are partitioning mainly in air phase and increasing the temperature from 70 to 100 degrees C their concentrations in air (Cair) have almost doubled. The analysis of surrogates was performed with a method based on solvent extraction and gas chromatographic-flame ionization detection (GC-FID) quantification.     

A New Cell for Single Sided Headspace Sampling and Evaluation of Barrier Function in Laminated Paperboard

A new cell for single sided headspace sampling has been developed for the analysis of volatile organic compounds from food packaging paperboard and laminated paperboard. The cell, which samples the volatile organic compounds over a selected surface, is useful for determining the barrier function of laminated paperboards with respect to volatile compounds. The analysis of volatile organic compounds is carried out by purge and trap capillary gas chromatography in combination with mass spectrometric detection and compound identification. The new sampling cell was constructed to facilitate specific analysis of organic compounds from only one side of a laminated paperboard. The construction and the operating principles of the new sampling device are described. The repeatability of the single sided headspace procedure was found to be quite good. Relative standard deviations of about 5–7% were obtained for the major compounds quantified in replicate headspace analyses of a laminated paperboard. The volatile compounds released from the inner side of a food packaging paperboard sample with different surface composition on the two sides were determined. The barrier function against volatile organic compounds of some laminated paperboards was investigated employing the new headspace cell.     

Analysis of volatile organic compounds in human urine by headspace gas chromatography-mass spectrometry with a multipurpose sampler.

A multipurpose sampler (Gerstel MPS), designed for liquid large volume, gaseous and headspace samples was used for the GC-MS analysis of organic volatiles in human urine. Headspace sampling with a volume-, temperature- and speed-controlled gas-tight syringe was combined with a temperature-controlled cold injection system (CIS) for cold trapping, enrichment and focusing of analytes. Regular 2-ml GC vials filled with 1 ml acidified urine were used as headspace sampling vials. A 100-vial autosampler tray was equipped with an additional temperature and heating time controlled "preheating station" for five vials. Profiles of organic volatiles in human urine were determined and 34 components identified. Trimethylamine (TMA) and 4-heptanone as two metabolites of medical interest were quantified. Calibration curves and intra assay imprecision for 4-heptanone concentrations in the range of 40 to 800 ng/ml showed a correlation coefficient of r = 0.9980 and a relative standard deviation (RSD) between 3.0 and 3.4%. Calibration curves and intra-assay imprecision for TMA concentrations in the range of medical interest from 0.5 to 20 micrograms/ml showed a correlation coefficient of r = 0.9968 and a RSD between 4.1 and 6.8%. The high practicability of the multipurpose sampler for both gaseous and liquid samples together with the here shown good reproducibility and sensitivity make this single CIS-GC-MS system very attractive for routine clinical use in metabolic profiling of organic volatiles (headspace) and non-volatiles (liquid).     

Headspace solid phase microextraction (HSSPME) for the determination of volatile and semivolatile pollutants in soils

We have investigated the use of headspace solid phase microextraction (HSSPME) as a sample concentration and preparation technique for the analysis of volatile and semivolatile pollutants in soil samples. Soil samples were suspended in solvent and the SPME fibre suspended in the headspace above the slurry. Finally, the fibre was desorbed in the Gas Chromatograph (GC) injection port and the analysis of the samples was carried out. Since the transfer of contaminants from the soil to the SPME fibre involves four separate phases (soil-solvent-headspace and fibre coating), parameters affecting the distribution of the analytes were investigated. Using a well-aged artificially spiked garden soil, different solvents (both organic and aqueous) were used to enhance the release of the contaminants from the solid matrix to the headspace. It was found that simple addition of water is adequate for the purpose of analysing the target volatile organic chemicals (VOCs) in soil. The addition of 1 ml of water to 1 g of soil yielded maximum response. Without water addition, the target VOCs were almost not released from the matrix and a poor response was observed. The effect of headspace volume on response as well as the addition of salt were also investigated. Comparison studies between conventional static headspace (HS) at high temperature (95 degrees C) and the new technology HSSPME at room temperature ( approximately 20 degrees C) were performed. The results obtained with both techniques were in good agreement. HSSPME precision and linearity were found to be better than automated headspace method and HSSPME also produced a significant enhancement in response. The detection and quantification limits for the target VOCs in soils were in the sub-ng g(-1) level. Finally, we tried to extend the applicability of the method to the analysis of semivolatiles. For these studies, two natural soils contaminated with diesel fuel and wood preservative, as well as a standard urban dust contaminated with polyaromatic hydrocarbons (PAHs) were tested. Discrimination in the response for the heaviest compounds studied was clearly observed, due to the poor partition in the headspace and to the slow kinetics of all the processes involved in HSSPME.     

化妆品中挥发性有机溶剂的通用检测方法

以化妆品配方中常见及禁用的36种有机溶剂为研究模板,建立了化妆品中挥发性有机溶剂残留评价初筛知识库、确证知识库和定量方法。初筛知识库包括双柱保留指数知识库和NIST质谱库。双柱保留指数知识库以保留指数为定性指标,选择极性的VF-1301ms和非极性的DB-5ms两根色谱柱,用顶空气相色谱-质谱法考察了36种有机溶剂在两种色谱分离系统中的保留特性。利用NIST MS search 2.0作为检索工具,同时建立了36种挥发性有机溶剂的顶空气相色谱-质谱定量方法。样品经60 ℃、30 min静态顶空后以连接了VF-1301ms石英毛细管色谱柱的气相色谱-质谱仪检测,外标法定量。方法检出限为0.01~3.3 μg/g,加标回收率为60.77%~126.60%。该方法从通用性的角度,为化妆品中挥发性有机溶剂残留的筛查、鉴别和定量提供方法,部分解决了测定化妆品中挥发性有机溶剂时需要针对不同检测目标建立不同方法以及潜在溶剂存在备选筛查的问题。     

Comparison of perchloroethylene extraction techniques in soil gas survey quantification

Subsurface pollution by volatile organic compounds has emerged as a widespread problem in industrialized countries. This study compares static headspace technique and methanol extraction/purge-and-trap analysis followed by thermal desorption/gas chromatography in attempts for quantification of gas survey results in the determination of these chemicals in soil. Several soils were contaminated with aqueous solution of perchloroethylene (PCE) (140 mg L⁻¹) using a vapor treatment method. Soil spiking took place up to 24 h in desiccator by exposing individual soil samples contained in open 40 mL glass vials to PCE evaporated from the solution. After exposure the samples were stored and analyzed within 2 days. The achieved results strongly suggest that gas extraction can provide quantitative results, regarding PCE concentration in soils, which are not significantly different from liquid based extraction analysis.      

Multiple headspace extraction-capillary gas chromatography (MHE-CGC) for the quantitative determination of volatiles in contaminated soils

A multiple headspace extraction-capillary gas chromatographic method for the quantitative, accurate, and rapid determination of volatiles in multicontaminated soil samples has been developed. A thick film fused silica column has been used and a nine-step multiple headspace extraction (MHE) determination performed. Calibration was achieved by introducing 1 μl of a standard solution of mixed volatiles into empty headspace vials, the presence of the matrix being unnecessary in multiple headspace extraction. Accuracy of determination by MHE-CGC and a simple method employing standard additions have been compared.     

Design and testing of a new sampler for simplified vacuum-assisted headspace solid-phase microextraction

The design and testing of a new and low-cost experimental setup used for vacuum-assisted headspace solid-phase microextraction (Vac-HSSPME) is reported here. The device consists of a specially designed O-ring seal screw cap offering gas-tight seal to commercially available headspace vials. The new polytetrafluoroethylene (PTFE) cap was molded by a local manufacturer and had a hole that could tightly accommodate a septum. All operations were performed through the septum: air evacuation of the sampler, sample introduction and HSSPME sampling. The analytical performance of the new sampler was evaluated using 22 mL headspace vials with 9 mL water samples spiked with polychlorinated biphenyls (PCBs). Several experimental parameters were controlled and the optimized conditions were: 1000 rpm agitation speed; 30 min extraction time; 40 °C sampling temperature; polydimethylsiloxane-divinylbenzene (PDMS-DVB) fiber. The lack of accurate Henry's law constant (K_H) values and information regarding how they change with temperature was a major limitation in predicting the phase location of evaporation resistance during Vac-HSSPME. Nevertheless, the combined effects of system conditions indicated the increasing importance of gas phase resistance with increasing degree of PCBs chlorination. Stirring enhancements were not recorded for the higher chlorinated PCBs suggesting that the hyperhydrophobic gas/water interface was the preferred location for these compounds. Analytically, the developed method was found to yield linear calibration curves with limits of detection in the sub ng L⁻¹ level and relative standard deviations ranging between 5.8 and 14%. To compensate for the low recoveries of the higher chlorinated PCB congeners in spiked river water the standard addition methodology was applied. Overall, the compact design of the new and reusable sample container allows efficient HSSPME sampling of organic analytes in water within short extraction times and at low sampling temperatures compared to other published HSSPME methods.     

Applications of a GC autosampler modified for headspace sampling

A GC autosampler designed for liquid injection was modified for static headspace sampling. The modification was very simple and involved replacement of the standard 10-μL syringe with a 100-μL gas-tight syringe. Liquid samples (0.2-1.0 mL) were placed in 2-mL vials, normally used for liquid sampling and an aliquot of the head-space above the liquid was withdrawn and injected into the GC. All parts of the sampling system were at ambient temperature. The system was found to be useful for several applications. Among those discussed in this paper are determination of ethanol in the blood or urine of individuals suspected of driving while intoxicated, residual organic solvents in pharmaceuticals, and screening of effluent waters from industrial plants for acrylonitrile.     

顶空气相色谱法测定化妆品中15种挥发性有机溶剂残留

建立了化妆品中15种挥发性有机溶剂残留的顶空气相色谱测定方法。样品经60 ℃、30 min静态顶空后,采用气相色谱-氢火焰离子化检测器进行检测,外标法定量。加标回收试验结果表明: 15种挥发性有机溶剂残留平均回收率为62.8%～116%,相对标准偏差均小于5%。方法的检出限为0.09～0.68 mg/kg。该方法可有效克服基体干扰,一次进样可同时分离和测定化妆品中15种挥发性有机溶剂,准确灵敏,简单快速,适用于化妆品中挥发性有机溶剂残留的检测。