高效液相色谱法同时检测棉织品中的9种有机氯农药残留

建立了高效液相色谱-二极管阵列检测器测定棉织品中9种有机氯农药含量的方法。采用丙酮-石油醚超声萃取法提取纺织品中的农药残留物,采用填料粒径为5 μm的ODS色谱柱,甲醇-磷酸水溶液(pH 2.27)体系为流动相,梯度洗脱,柱温30 ℃,流速0.8 mL/min,在波长230 nm下检测。9种农药在0.5~10 mg/L范围内峰面积与其浓度具有良好的线性关系(r2>0.9988)。该法简便、准确、灵敏度高、重现性好、回收率高(85.5%~99.6%),可用于纺织品中有机氯杀虫剂和除草剂含量的测定。     

Simultaneous determination of benomyl and morestan residues in waters by synchronous solid-phase spectrofluorimetry

In this paper a new, sensitive, and simple method for simultaneous determination of pesticides morestan and benomyl at trace levels in waters is reported. Both chemicals, showing native fluorescence in solution at neutral medium, were fixed on C-18 silica gel at pH 1, giving a fluorescent system. The benomyl-morestan-silica gel system, after dry, was packed in a 1-mm silica cell and its synchronous fluorescence spectra were recorded at =80 nm for determination of benomyl and =25 nm for determination of morestan. Measurements of fluorescence were performed at ₁=289 nm and ₂=367 nm for benomyl and morestan analysis, respectively. The applicable concentration ranges were from 0.5 to 15.0 ng·ml^–1 for benomyl and from 0.6 to 15.0 ng·ml^–1 for morestan, with relative standard deviations of 1.2 and 1.5% for benomyl and morestan, respectively, being 0.15 and 0.18 ng·ml^–1 its respective detection limits. The method was applied to the simultaneous determination of residues of both pesticides in water of different provenances.     

Derivatization of Humic Compounds: An Analytical Approach for Bound Organic Residues

Abstract

Bound residues of pesticides and their metabolites are defined as being nonextractable with organic solvents, but partly extractable together with the humic matrix by NaOH or other solvents suitable to extract humic compounds. Recently, an improvement in humus extraction from soils was achieved upon derivatization of the organic matter with silylating reagents at room temperature. By this method 70–90% of the organic carbon or nitrogen either from soil or from humin became soluble in organic solvents. The extracts were analyzed by means of ¹³C NMR-spectroscopy. The spectra were well resolved with signal-separation of less than 1 ppm. The extracted humic compounds were of rather low molecular weight, ranging from 300 to 4000 to 6000 d or more.

¹⁴C-labeled residues of pesticides or other xenobiotics found to be nonextractable after exhaustive organic solvent extraction became readily dissolved along with most of the humic matrix using this derivatization procedure. Between 60–80% of ¹⁴C anilazine residues or of ¹⁴C-labeled chlorinated phenols or anilines originating from both previously solvent extracted soil samples or from humin became solubilized in organic solvents.     

Simultaneous determination of three organophosphorus pesticides residues in vegetables using continuous-flow chemiluminescence with artificial neural network calibration

In this article, a continuous-flow chemiluminescence (CL) system with artificial neural network calibration is proposed for simultaneous determination of three organophosphorus pesiticides residues. This method is based on the fact that organophosphorus pesticides can be decomposed into orthophosphate with potassium peroxodisulphate as oxidant under ultraviolet radiation and that the decomposing kinetic characteristics of the organophosphorus pesticides with different molecular structure are significantly different. The produced orthophosphate can react with molybdate and vanadate to form the vanadomolybdophosphoric heteropoly acid, which can oxidize luminol to produce intense CL emission. The CL intensity of the solution was measured and recorded every 2 s in the range of 0-250 s. The obtained data were processed chemometrically by use of a three-layered feed-forward artificial neural network trained by back-propagation learning algorithm, in which input node, hidden node and output nodes were 65, 21 and 3, respectively. The proposed multi-residue analysis method was successfully applied to the simultaneous determination of the three organophosphorus pesticides residue in some vegetables samples.     

Determination of organochlorine pesticides in ground water samples using solid-phase microextraction by gas chromatography-electron capture detection

A direct immersion solid-phase microextraction coupled with gas chromatography-electron capture detection (SPME-GC-ECD) method was optimized and validated for the quantitative determination of 18 organochlorine pesticides in ground water. Ionic strength, stirring speed, adsorption and desorption time and pH were some of the parameters investigated in order to select the optimum conditions for SPME with a 50/30 DVB/CAR/PDMS fiber coating. The SPME-GC/ECD method showed good linear response below 10 ng L⁻¹ with R² values in the range of 0.9950–0.9997. The repeatability of the measurements were lower than 10%. Values of relative recoveries located within the acceptable range (80–120%). Limits of quantification (LOQ) from 4.5 × 10⁻³ to 1.5 ng L⁻¹ were obtained. On average 8 organochlorines were found per sample, even so all the 18 organochlorines were quantified among them. Substances such as endrin ketone, γ-BHC and β-BHC were the pesticides determined in larger concentration (0.06–305 ng L⁻¹), while methoxychlor and aldrin in smaller amounts (0.151–1.55 ng L⁻¹). Measured levels of organochlorine pesticides were above the limits established by Brazilian regulations.     

超高效液相色谱-四极杆-飞行时间质谱法快速筛查茶叶中的204种农药残留

利用超高效液相色谱-四极杆-飞行时间质谱(UPLC-Q-TOF/MS)技术建立了茶叶中204种农药残留的快速筛查和确证检测方法。样品采用乙腈提取,经Carb-PSA固相萃取小柱净化,用乙腈-甲苯(3:1, v/v)洗脱,采用UPLC-Q-TOF/MS检测,外标法定量。建立了204种农药的一级精确质量数据库和二级谱图库,通过化合物的精确质量数、保留时间、同位素比值等信息对检测结果进行自动检索,从而在无对照标准品的情况下完成了204种农药的定性鉴定。结果表明,该方法可以同时对茶叶中204种农药残留进行快速筛查,在10、20、50 μg/kg 3个添加水平下的平均回收率为68.1%~117.2%,相对标准偏差为3.1%~18.9%。定量限均小于10 μg/kg。采用本方法对4份阳性样品进行检测,所得结果与GB/T 23205-2008的检测结果基本一致。该方法快速、灵敏、准确,可用于茶叶中204种农药残留的快速筛查。     

对几种氨基甲酸酯类农药的荧光特性研究

研究了有机物分子结构与荧光产生之间的关系。利用这一理论分析了西维因、克百威、残杀威等几种常用的氨基甲酸酯类农药的分子结构并揭示了它们的荧光光学特性,从而确定了氨基甲酸酯类农药产生荧光的特性,为进一步利用荧光分析法对氨基甲酸酯类农药进行检测提供理论依据。并且利用稳态荧光光谱仪对西维因和克百威标准溶液进行了荧光光谱实验,结果表明,氨基甲酸酯类农药在一定的溶剂条件下是能够受激发荧光的,是可以利用荧光光谱分析法来对它们进行检测．     

一种新的农药残毒快速检测装置

本文报道了一种新的农药残毒快速检测装置。该装置基于酶催化动力学原理,以酶抑制率反映蔬菜中残留农药的总毒性。该装置集化学分析、光机电、信息、生物等技术于一体,可对六种样品进行同时检测。测量准确度高,精密度好,方便快速,适合于各种实际应用场合,具有广泛的应用前景。     

羟基化多壁碳纳米管分散固相萃取-气相色谱-质谱法测定茶叶中21种有机磷农药

建立了用羟基化多壁碳纳米管(MWCNTs-OH)、N-丙基乙二胺键合固相吸附剂(PSA)和MgSO₄作为吸附剂的改进QuEChERS-气相色谱-质谱快速检测茶叶中21种有机磷农药的方法。茶叶中残留的农药经正己烷-丙酮(2 : 1, v/v)混合溶剂提取,以MWCNTs-OH、PSA和MgSO₄去除杂质,离心、过滤后经气相色谱-电子轰击源质谱测定,外标法定量。结果表明,目标化合物在0.01~0.50 mg/kg范围内的线性关系良好。空白茶叶样品在低、中、高3个添加水平下的平均回收率为81.5%~109.4%,相对标准偏差(n=5)为2.3%~10.6%,定量限为0.001~0.040 mg/kg。该方法操作简单、快速、灵敏、成本低,能满足茶叶中常见有机磷农药残留的检测要求。     

QuEChERS-气相色谱-质谱联用法快速测定人参中农药多残留

建立了QuEChERS-气相色谱-质谱联用（GC-MS）法同时测定人参中20种农药残留量的检测技术。样品前处理采用改进的QuEChERS方法,人参粉加水浸润后,用乙腈均质提取,用N-丙基乙二胺（PSA）和MgSO₄净化,结合GC-MS检测系统,在电子轰击源（EI）选择离子监测（SIM）模式下进行检测,使用HP-5毛细管柱进行分离。在优化条件下,20种农药在一定范围内线性关系良好,相关系数大于0.990,方法检出限（信噪比S/N=3）为0.001~0.007 mg/kg,定量限（S/N=10）为0.002~0.024 mg/kg,平均回收率为70.41%~114.06%,相对标准偏差（RSD）为0.76%~15.47%。该方法操作简单快捷、灵敏度高。