贻贝中有机氯残留的气相色谱分析

建立了贻贝中有机氯农药残留的气相色谱法,方法检测限：666为0．315×10^-3mg／kg,DDT为4．60×10^-3mg／kg,分别添加5．0×10^-3、10．0×10^-3和50．0×10^-3mg／kg三个浓度水平加标回收范围为82．6—108％,RSD为1．03—7．84％。该方法具备较高的灵敏度和准确度,适合实验室分析。     

QuEChERS/GC测定蔬菜中24种有机磷农药残留

对QuEChERS农药多残留同时分析方法进行了样品提取及净化方面的改进,建立了蔬菜中24种有机磷类农药残留QuEChERS/GC同时分析的方法.样品用0.1%醋酸的乙腈提取,净化采用分散固相萃取的方式,采用DB-1701(30m×0.32mm×0.25μm)毛细管柱分离,FPD(P)检测.24种农药的浓度范围在0.002～0.05mg/kg时,回收率在79%～103.5%之间,RSD为1.1%～5.6%.各农药的检测限:苯硫磷为0.01mg/kg,三硫磷、三唑磷为0.004mg/kg,其他21种为0.002mg/kg.该方法步骤简单,消耗费用低,净化效果好,具有良好的灵敏度、回收率和重现性.     

Measurement of pesticide residues in food based on diffuse reflectance IR spectroscopy

This paper describes nondestructive pesticide measurement of agricultural products based on Fourier transform infrared diffuse reflectance spectroscopy (FT-IR-DRS). Both FT-IR-DRS spectra and the concentration of the pesticide residues are measured for real lettuce samples. Thereafter, the calibration models to estimate the residual concentration of the pesticides are derived by the partial least square regression of the spectra. Cross validations of the calibration models are also carried out. By using this method, it takes two minutes to measure the multi-elements of pesticide residues in a sample lettuce head. Food safety inspection could be enhanced based on FT-IR-DRS.     

Automated resolution of nontarget analyte signals in GC x GC-TOFMS data using parallel factor analysis

We previously reported a method for the automated (objective) selection of a PARAFAC model having an appropriate number of factors for mathematical resolution of signal from a target analyte in GC x GC-TOFMS data (i.e., for an analysis in which the identity of the analyte is known a priori). While the previous target method has been successfully applied in several studies, the target method requires that the identity of the analyte be known. Also, multiple applications of the target method are required in cases where several analytes of interest are present in a single subsection of the chromatogram. Thus, having to know the analyte identity a priori restricts the applicability of the automated implementation of PARAFAC. The method presented in this report generalizes the previous method to allow analysis of one or more nontarget analyte signals in a subsection of a GC x GC-TOFMS chromatogram (i.e., for analyses when identities of analyte and interferences are not known a priori), thereby addressing and overcoming the limitations of the target method. Herein, we put the nontarget analyte PARAFAC method into theoretical context and illustrate the mechanics of the method using simulated data. We use real experimental GC x GC-TOFMS data to demonstrate the broad applicability of the method, with various analysis situations selected to illustrate challenging chemical analysis scenarios.     

蔬菜中吡虫啉农药残留分析方法

针对蔬菜中吡虫啉残留分析没有国标可执行的问题,着手对此进行了一些研究,提出了一种简单、快速且较为经济的对残留量的检测分析方法.用二氯甲烷,采用匀浆法提取,并用安捷伦的C18柱(500 mg;6 mL)进行净化.用高效液相色谱仪测定,外标法定量.其特点是方法简便、快速,结果准确.检测波长269nm;色谱柱C18 XDB 250mm×4.6min×5μm;流动相:乙腈:水=40:60(V/V);该方法标准曲线相关系数0.99999.     

Potential analytical applications of interfacing a GC to an FT-ICR MS: fingerprinting complex sample matrixes

Details of interfacing a high-pressure gas chromatograph to the internal ion source of a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) are described. We present our preliminary results and potential analytical applications of GC/FT-ICR for analyzing complex biological and environmental sample matrixes, such as petroleum mixtures. Based on GC/FT-ICR data, rapid characterization of various automobile gasoline samples is possible. Comparison between acquired data from the GC/FT-ICR MS (in broadband mode) and a commercial GC quadrupole mass spectrometer (QMS) (over a wide mass range) indicates that sensitivity of the GC/FT-ICR MS is an order of magnitude lower. High mass resolution and mass measurement accuracy of FT-ICR MS can be utilized for unambiguous molecular formula identification of unknown analytes.     

基质固相分散萃取-气相色谱同时测定茶叶中有机氯及拟除虫菊酯类农药残留

建立了气相色谱-电子捕获检测器(GC-μECD)同时测定茶叶中14种有机氯和8种拟除虫菊酯类农药残留。采用基质固相分散(Matrix Solid Phase Disperse,MSPD)技术对茶叶样品进行前处理,用气相色谱-电子捕获检测器快速定性定量分析。MSPD集提取、过滤、净化于一步完成,避免了样品均化、转溶、乳化、浓缩造成待测农药组分的损失,大大提高了方法的准确性和精密度。添加回收实验结果表明:22种农药的平均回收率为83.5%~112.6%,相对标准偏差为2.5%~10.6%,方法检出限为0.002~0.02mg/kg。该方法灵敏度、准确度和精密度均符合农药残留测定的要求。     

QuEchERS法测定蔬菜中有机磷类农药多残留分析

本文运用农药多残留分析中的一种简便、快速、价格低廉的分析方法—QuEchERS法。其采用一种新的样品前处理方法,从蔬菜中提取净化残留农药(包括11种有机磷农药),运用GC/MS进行分析检测,根据有机磷农药种类差异,其最小检出限在5.6~18.2μg/kg之间,回收率在67.7%~105.3%之间,相对标准偏差不大于10.6%,实验表明本方法适用蔬菜中有机磷农药多残留分析。     

植物药材农药残留药典标准分析研究

该文系统研究我国药典与主要发达国家药典中涉及植物药材农药残留限量及检测技术的相关规定,探讨我国药典标准在农药残留规定方面的不足。结果表明:我国药典的农药残留限量标准缺乏针对性和实效性,应重视登记使用农药和国际关注的农药种类;检测技术则应以定性准确、灵敏度高为特点的质谱技术作为检测手段制定农药残留检测标准方法。     

Use of liquid chromatography coupled to quadrupole time-of-flight mass spectrometry to investigate pesticide residues in fruits

In this paper, the potential of coupling liquid chromatography with hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF) for the determination of pesticides in a variety of fruit samples (orange peel and flesh, banana skin and flesh, strawberry and pear) has been explored. The quantitative application at residue levels has been proven for two insecticides (buprofezin and hexythiazox), which were satisfactorily determined at three concentration levels, 0.1, 1, and 5 mg/kg, obtaining a suitable linearity range (correlation coefficient>0.99) of more than 2 orders of magnitude. Satisfactory recoveries have been obtained for both compounds at the three levels tested in all sample matrices, with lowest calibration levels (LCL) of 0.075 and 0.01 mg/kg. The excellent potential of QTOF for identification purposes is illustrated by the high number of identification points (IPs) earned, up to 21, at the highest concentration of 5 mg/kg, or between 11 and 21 at the 0.1 and 1 mg/kg levels. The application of LC-QTOF MS to real samples revealed the presence of several positives at concentrations close to the LCL, all of which were confirmed with more than 11 IPs. The potential of QTOF for elucidation of nontarget analytes has also been demonstrated by the finding of one transformation product (TP) of buprofezin in a banana skin sample. This TP was identified by obtaining the full scan product ion spectra at different collision energies with acceptable accurate mass deviation. The work performed in this paper illustrates the suitability and excellent confirmatory potential of LC-QTOF MS for pesticides residues analysis in food samples.     

气相色谱法测定茶叶中多种有机磷农药残留

建立了气相色谱法测定茶叶中多种有机磷农药残留的方法。样品经二氯甲烷提取后以1.0μL注入色谱分析柱,130～190℃程序升温检测,样品最小检测浓度0.005～0.040mg/kg,平均回收率88%～95%,RSD<5.0%(n=6)。     

毛细管柱气相色谱法测定土壤中有机磷农药残留

运用毛细管柱气相色谱及外标法定量测定土壤中的氧化乐果、久效磷及乐果等9种有机磷农药残留,相对标准偏差为1.9%-5.3%,两种加标水平的回收率为84.0%-102.8%和80.0%-104.0%。结果表明该分析方法的灵敏度高、精密度好、回收理想、结果准确,完全适用于土壤样品的分析。     

毛细管柱气相色谱法测定土壤中有机磷农药残留

运用毛细管柱气相色谱及外标法定量测定土壤中的氧化乐果、久效磷及乐果等9种有机磷农药残留,相对标准偏差为1．9％～5．3％,两种加标水平的回收率为84．0%-102．8％和80．0%-104.0%。结果表明该分析方法的灵敏度高、精密度好、回收理想、结果准确,完全适用于土壤样品的分析。     

Strategies for the analysis of polar solvents in liquid matrixes

Various approaches to the analysis of polar compounds in different matrixes by solid-phase microextraction (SPME) were studied. The analysis of polar analytes in nonpolar matrixes was performed with custom-made SPME fibers coated with Nafion perfluorinated resin. The sensitivity of this fiber in this type of analysis was better by 1 order of magnitude on average as compared to those of any of the commercially available fibers. The fiber was the most sensitive for the most polar of the compounds studied, i.e., methanol. Determination of methanol, ethanol, and 2-propanol in unleaded gasoline was illustrated. Except for methanol, the fiber did not perform very well in the analysis of alcohols in water. The fiber was capable of extracting water from benzene. SPME analysis of polar compounds in water was studied using aqueous solutions of acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), 2-propanol, 2-methyl-2-propanol, and tetrahydrofuran. Fibers coated with poly(dimethylsiloxane)/divinylbenzene yielded the highest sensitivity in this type of analysis. Low- or sub-ppb detection limits were obtained for all the analytes with FID detection when the samples were saturated with NaCl. Since fibers of this type extract analytes by adsorption rather than absorption, nonlinear responses were observed when all the analytes were allowed to equilibrate because of the limited number of adsorption sites on the surface of the coating and displacement of compounds with low distribution ratios by compounds with high distribution ratios (mainly MIBK). Two approaches allowed a significant improvement in linearity: extraction of a vigorously stirred sample for a short time, or extraction under static conditions for a time much shorter than that required for equilibration of all the analytes. In both cases the amount of MIBK extracted was significantly reduced, while the remaining analytes were affected to a much lesser degree. The sensitivity of acetone determination was greatly improved by in-solution derivatization with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride and extraction of the oxime formed.     

On advanced solution strategies to overcome locking effects in strong discontinuity approaches

This paper is concerned with the analysis of locking effects resulting from different orientations of micro‐defects and those of the corresponding macro‐defects. Based on a mixed‐mode material model embedded within the framework of the strong discontinuity approach (SDA), the described locking effect is illustrated by means of a crack analysis of a notched concrete beam. To overcome the deficiency of the proposed finite element model, the original SDA is modified and extended. For that purpose, two different advanced numerical formulations are developed: a rotating crack approach and a multiple crack approach. Restricting the governing equations to the material point level, a standard return‐mapping procedure is applied to the algorithmic formulations of both models. The applicability and the performance of the proposed numerical implementations are investigated by means of a re‐analysis of the two‐dimensional notched concrete beam. Copyright © 2005 John Wiley & Sons, Ltd.     

Extraction and quantitative analysis of iodine in solid and solution matrixes

129I is a contaminant of interest in the vadose zone and groundwater at numerous federal and privately owned facilities. Several techniques have been utilized to extract iodine from solid matrixes; however, all of them rely on two fundamental approaches: liquid extraction or chemical/heat-facilitated volatilization. While these methods are typically chosen for their ease of implementation, they do not totally dissolve the solid. We defined a method that produces complete solid dissolution and conducted laboratory tests to assess its efficacy to extract iodine from solid matrixes. Testing consisted of potassium nitrate/potassium hydroxide fusion of the sample, followed by sample dissolution in a mixture of sulfuric acid and sodium bisulfite. The fusion extraction method resulted in complete sample dissolution of all solid matrixes tested. Quantitative analysis of 127I and 129I via inductively coupled plasma mass spectrometry showed better than +/-10% accuracy for certified reference standards, with the linear operating range extending more than 3 orders of magnitude (0.005-5 microg/L). Extraction and analysis of four replicates of standard reference material containing 5 microg/g 127I resulted in an average recovery of 98% with a relative deviation of 6%. This simple and cost-effective technique can be applied to solid samples of varying matrixes with little or no adaptation.     

气相色谱法测定蒜苗中8种有机磷农药残留

采用气相色谱仪配备火焰光度检测器测定蒜苗中8种有机磷农药的残留.试样在前处理过程中先进行微波处理,比较不同微波功率及微波时间对去除含硫化合物的影响,结果证明试样经640W功率下微波处理40s后硫化物去除效果理想,且对8种有机磷农药影响较小.在0.04mg/kg、0.1 mg/kg和0.2mg/kg三个加标水平下,8种有机磷农药的回收率为71.6%～97.1%,相对标准偏差为1.9%～8.6%,检出限为0.007～0.018mg/kg.试验结果均符合蔬菜有机磷农药的检测.     

地表水中有机磷农残测定的前处理方法比较

分别采用液液萃取法和固相萃取法提取地表水样品中的有机磷农药残留。液液萃取法的方法检出限为0.05~0.2 ng/mL,加标回收率为86%~103%,相对标准偏差为2%~7%;固相萃取法的方法检出限为0.03~0.05 ng/mL,加标回收率为49%~118%,相对标准偏差为5%~18%。液液萃取法处理不同类型基体水样的测试稳定性较好,固相萃取法则对于洁净环境水体中痕量有机磷农药残留的富集更为适用。