虾仁中氯霉素残留量的气相色谱测定

建立了用配有电子俘获检测器(ECD)的气相色谱仪来测定虾仁中的氯霉素含量的方法.试样用乙酸乙酯提取,正己烷去杂,硅胶柱纯化,BSTFA+TMCS(99:1)试剂硅烷化.以GC ECD方式测定,外标法定量.当添加水平为0.2×10-9～1.0×10-9μg/kg时,回收率为70%～110%;相对标准偏差为1.0%～5.0%;线性相关系数r大于0.998.     

GC-ECD法快速测定饮用水中卤乙酸的方法研究

通过优化卤乙酸衍生化条件、改进色谱条件，建立了一种利用短程色谱柱快速测 定饮用水中5种卤乙酸的GC-ECD方法。方法的特点是色谱程序简单、运行时间短，色谱运行时间仅为10．8min，远少于通常的运行时间。方法的检出限较低，精密度较好，除MCAA外，MBAA、DCAA、TCAA和DBAA的检出限和相对标准偏差分别小于0．46μg／L和4％（n=7）；5种卤乙酸的加标回收率在86．6％～109．3％之间，满足EPA 6251B标准方法的要求。     

粮谷中灭草松残留量检测的GC及GC-MS/MS研究

试验证明GC-ECD及GC-MS／MS两种方法均能用于粮谷中残留除草剂灭草松的测定。GC-MS／MS法可同时进行定性和定量分析,测定结果的可靠性较高。GC-ECD法具有较高的灵敏度,用于定量分析的效果较好。提出一种可与上述两种方法接用的试样预处理方法。10 g试样用甲醇提取其中的测定组分,再用正己烷萃取除去脂肪。用稀盐酸调节水相的酸度至pH≤3, 用二氯甲烷将灭草松萃取至有机相。在45℃减压干燥除去溶剂,所得浓缩的残渣溶于0．2 mL甲醇中并进行甲烷化和纯化(用固相萃取法),所得残留灭草松溶于1 mL正己烷中供GC-ECD或 GC-MS／MS测定。用两种方法进行粮谷试样的分析,测定结果的RSD值依次为2．3％-4．7％和 3．5％-6．7％。用标准加入法测得两方法的回收率依次为77％-98％和80％-102％,方法的检出限为0．01 mg·kg-1。     

Dual-column GC analysis of mediterranean fish for ten organochlorine pesticides and sixty two chlorobiphenyls

The simultaneous analysis of α-HCH, β-HCH, γ-HCH, HCB, p,p′-DDD, p,p′-DDT, p,p′-DDE, o,p′-DDT, mirex, dieldrin and 62 chlorobiphenyl congeners on two parallel capillary GC columns of different polarity is described for nine Mediterranean fish species. Ten commercially available columns with stationary phases completely characterized in respect of their PCB elution patterns were considered for dual-column GC-ECD analysis. The combination of a 60 m × 0.25 mm i.d. column coated with a 0.25 μm film of 50% diphenyl dimethylsiloxane and a series combination of a 25 m × 0.25 mm i.d. column coated with a 0.25 μm film of 5% diphenyl dimethylsiloxane with a 25 m × 0.22 mm i.d. column coated with a 0.10 μm film of 1, 10-dicarba-closo-dodecarborane dimethylpolysiloxane furnished the highest number of separated chlorobiphenyl congeners (104). The dual-column GC system performed with high stability and reproducibility over a broad concentration range (1–3000 ng/g lipid) of the organochlorine compounds in the investigated fish.     

Comparison and Evaluation of Extraction Media and Their Suitability in a Simple Model to Predict the Biological Relevance of Heavy Metal Concentrations in Contaminated Soils

Abstract

The concentrations of heavy metals in agricultural soils are increasing gradually from various diffuse sources. The metals can transfer from contaminated soils into the growing plants or may affect the respiration rate of soil microorganisms.

In the first part of this paper, the following simple model to predict the biorelevant metal concentration in anthropogenically or artificially contaminated soils is reported: log M_p = α + β log [M_NaNO3] log M_R = α' + β' log [M_NaNO3] log M_P = log Metal concentration in test plant (mg/kg dry weight) log M_R = log percent Redution in the respiration or enzyme activity [M_NaNO3] = Metal concentration in NaNO3-soil extract (mg/kg soil) α and β & α' + β' = Intercepts and slopes of the linear regression lines.

The model has been tested in laboratory experiments, in growth experiments either in a greenhouse or in the field. Also, an attempt is made to present a theoretical interpretation.

Critical concentrations are calculated with the help of the relationship between metal concentration in soil solution [M_NaNO3] and metal concentration in plants. The critical concentration, which is able to induce either phyto- or zootoxic concentrations in the plant parts (productive or vegetative) or reduce their growth or to reduce significantly the growth of soil microorganisms, are found to be uniform in a wide range of soils (pH 3 to 8 and CEC 10–50 millimol/100g soil), the critical concentrations of NaNO₃ in soil extracts are comparable with the values obtained with plant growth experiments in nutrient solution and also with the concentrations obtained from soil respiration experiments reported in literature.     

Determination of traces of polychlorinated biphenyls in pigments

PCB patterns in a new pigment brand are characterized using GC-MS in the single ion monitoring (SIM) mode. Specific PCBs are then used as external standards for GC-ECD quantification. The following PCB isomers or groups of isomers have to be determined (CB = chlorobiphenyl): total diCBs, 3,3′ diCB, 2,4,5-triCB, 2,2′,4,4′-tetraCB, 2,2′,5,5′-tetraCB, total pentaCB, total hexaCB. Capillary gas chromatography is performed on preseparated solutions (LC) of pigment. An electron caputure detector (ECD) is used for PCB detection and quantification. Calibration is based on the peak areas of external standards and the PCB isomers in the samples, all normalized for internal standard peak areas. Total concentrations of diCB, hexaCB, or pentaCB in a sample are calculated by summing the individual PCB isomer concentrations within the correcsponding elution ranges. Determination limits lie in the range of 1 mg/PCB-isomer/kg pigment.     

A quick analytical method using direct solid sample introduction and GC-ECD for pesticide residues analysis in crops

In this work, an analytical method for GC using direct solid sample introduction was developed to tackle the problem regarding quick detection of pesticide residue in crops and large-scale screening of samples. 10 mg of the crop solid sample without sample pre-treatment was directly introduced into a modified split/splitless injector for GC analysis. A split/splitless injector was modified to quickly remove oxygen and low boiling-point matrices of the sample. The whole sampling procedure was simple and it required less than 5 min. The experimental parameters including injector-port temperature, removal of oxygen and low boiling point matrices, size and the amount of the solid sample, oven temperature program were studied. Satisfactory recoveries of 6 pesticides (methyl parathion, fenitrothion, aldrin, dieldrin, endosulfan, o,p′-DDT) were obtained in maize and rice sample. Relative standard deviation was less than 15%. Experimental results showed that the proposed method was quick and reliable for pesticide residues analysis in crops.     

茶叶中有机氯和拟除虫菊酯多种农药残留同时分析的样品前处理研究

建立了茶叶中同时分析12种有机氯和拟除虫菊酯类农药残留的样品提取和固相萃取(SPE)前处理方法.试样在超声条件下用正己烷提取后用自制弗罗里圭(florisil)/石墨化碳复合固相萃取小柱净化,然后采用气相色谱-电子捕获检测器(GC-ECD)测定.研究结果表明,当茶叶中农药加标在4.93～201.00 ng/g范围内时,添加回收率为68.9%～112.2%,相对标准偏差为2.43%～15.8%,方法的检出限范围在2.52～10.59 ng/g.     

Evaluation of two commercial capillary columns for the enantioselective gas chromatographic separation of organophosphorus pesticides

The separation of the enantiomers of 13 organophosphorus pesticides (OPPs) has been investigated by gas chromatography (GC) with flame ionisation detection (FID) using two different commercially available chiral columns, Chirasil-Val (l-valine-tert-butylamide) and CP-Chirasil-Dex CB (heptakis (2,3,6-tri-O-metil)-β-cyclodextrin). Using the Chirasil-Val column no chiral resolution was obtained for the OPPs investigated under any tested experimental condition. The use of the CP-Chirasil-Dex CB stationary phase enabled good individual enantiomeric separation of two OPPs, ruelene and trichlorfon and partial separation of naled, chloretoxyphos, isophenphos and metamidophos. Also, the obtained chromatographic results showed that Chirasil-Dex could resolve enantiomers through the combination of different mechanism (e.g. formation of inclusion complexes and/or interactions outside the cyclodextrin cavity).

Under optimised conditions, precision, linearity range and detection limits were evaluated for the enantiomers of ruelene and trichlorfon using CP-Chirasil-Dex CB column and electron capture detection (ECD). By using the GC-ECD method the enantiomers of these OPPs could be satisfactorily detected at very low concentration levels. The detection limits observed were 1.5 ng mL⁻¹ and 11.5 ng mL⁻¹ for the enantiomers of trichlorfon and ruelene, respectively.