键合固定相气相色谱法分离测定蔬菜中有机磷农药的残留量

本文采用ＰＥＧ－２０Ｍ键合固定相色谱柱气相色谱法分离测定蔬菜中十种有机磷农药的残留量。对色谱分析条件,标准工作曲线,回收率等进行试验,结果表明方法简单,快速,灵敏度高,线性关系良好,能同时测定多种有机磷农药残留量。     

气相色谱-质谱联用法测定水果中环氧七氯残留量的不确定度评定

对《蔬菜、水果中农药残留量的气质联用测定方法》测定水果中环氧七氯农药残留量的不确定度进行了评定,分析和量化了影响测定结果的不确定度分量,将不确定度分量合成,得到环氧七氯农药残留量的扩展不确定度为0．25μg／g。     

蔬菜中有机磷和氨基甲酸酯类农药多残留联合检测方法

有机磷和氨基甲酸酯类农药是蔬菜生产中常用的杀虫剂，我国70%的有机磷杀虫剂是剧毒、高毒农药。农药如果使用不当，不但药效不好，还会发生药害，污染环境，造成人畜中毒。因此，加强对农药残留的监控，禁止农药残留超标的蔬菜进入市场，确保消费安全已成为当务之急。本文报道用毛细管气相色谱法测定蔬菜中有机磷和氨基甲酸酯类农药多残留的联合检测方法。     

蔬菜中氨基甲酸酯类农药残留的固相微萃取分离和HPLC法检测

采用固相微萃取制样,荧光检测器高效液相色谱法测定了蔬菜中氨基甲酸酯农药残留. 确定了影响固相微萃取效果的萃取头涂层、萃取条件、洗脱条件和蔬菜样品分析处理方法. 结果表明,蔬菜中氨基甲酸酯类农药的检出限在0.4×10-9～40×10-9 g/g范围内,线性范围为0.05～1 mg/L,回收率74.4%～108.4%,相对标准偏差(RSD)4.26%～13.97%.     

气相色谱-离子阱质谱法测定蔬菜中9种有机磷农药的残留量

建立气相色谱-离子阱质谱法测定蔬菜中9种有机磷农药残留的方法.样品经乙酸乙酯提取、无水硫酸钠脱水、活性炭小柱净化,浓缩后通过气相色谱-离子阱质谱进行测定.9种有机磷农药的浓度在0.05～1.0μg/mL范围内与其对应的色谱峰面积具有良好的线性关系(r＞0.999).在3个不同添加浓度下的平均回收率为76.5%～101.2%,测定结果的相对标准偏差为3.9%～9.4%(n=7).该方法快速、准确、操作简便,能满足蔬菜中有机磷农药残留的检测要求.     

化学反应—气相色谱法测定蔬菜中杀虫双残留量

本文介绍了一种运用化学反应转化，气相色谱法快速测定蔬菜中杀虫双残留量的方法，其检测限为０．０１ｍｇ／ｋｇ。     

多壁碳纳米管固相萃取净化气相色谱法分析蔬菜中有机氯和拟除虫菊酯农药残留

建立了多壁碳纳米管为吸附剂的固相萃取(SPE)净化、气相色谱-电子捕获检测(GC-ECD)测定蔬菜中6种有机氯和7种拟除虫菊酯农药的方法。采用双柱(HP-50和HP-1色谱柱)双检测器进行定性和定量分析。蔬菜样品采用乙腈提取,多壁碳纳米管SPE柱净化,正己烷溶解上样,丙酮-正己烷(7:3, v/v)洗脱,13种农药中有11种农药的添加回收率高于70%。将该净化方法用于荷兰黄瓜、卷心菜、红圣女果、奶油生菜、紫甘蓝、韭菜、大葱和洋葱等样品的净化,与弗罗里硅土SPE柱相比较,净化效果更好,表明多壁碳纳米管具有较强的吸附去除色素的能力,可以避免色素对测定的干扰。     

液相色谱-串联质谱法测定蔬菜、水果中80种农药残留

建立了同时测定蔬菜、水果中有机磷类、酰胺类、氨基甲酸酯类等80种农药残留的液相色谱-串联质谱(LC-MS/MS)检测方法。样品经乙腈提取,N-丙基乙二胺(PSA)和C18填料分散固相萃取净化,C18柱分离后,在电喷雾正离子化模式下,于三重四极杆质谱仪,动态多反应监测方式测定。结果表明:80种农药的线性范围均超过3个数量级,且r≥0.99;对6种蔬菜、水果样品分别进行0.01、0.05mg/kg2个水平的加标回收实验(n=5),其平均回收率分别为64%～118%和72～108%;RSD分别为3.7%～29.1%和3.4%～27.9%;80种农药的方法检出限(S/N=3)为0.02～3μg/kg。方法快速、准确、灵敏,适用于蔬菜、水果中该80种农药的同时分析。     

LC-TOF/MS无标准品定性筛查水果蔬菜中210种农药残留

建立了基于农药化合物列表(Database)无需标准品定性筛查水果蔬菜中210种农药的LC-TOF/MS方法。农药化合物列表包含农药的名称、保留时间、分子式和精确质量数。实验对检索中所需的精确质量数、保留时间窗口和离子化形式等进行了对比优化,用以提高筛查准确度,避免假阳性和假阴性结果的产生。采用标准溶液和基质添加样品,对方法的准确性、稳定性以及检测能力进行了探讨,结果表明,所有农药均能在10.0μg/kg(一律标准)下检出,化合物检索得分的相对标准偏差(RSD)均<20%。只需通过1次样品前处理,1次仪器测定,借助农药化合物列表实现无标准品对照下,对210种农药进行快速定性筛查,并且其性能指标均能够满足日常检测的需要。采用本方法对20个市售水果蔬菜样品进行了测定,发现了16种农药残留,包括常用农药,如多菌灵、烯酰吗啉、啶虫脒、甲霜灵、莠去津和噻菌灵等。     

微波消解-石墨炉原子吸收光谱法和原子荧光光谱法测定蔬菜中痕量元素

用微波消解对蔬菜进行前处理，石墨炉原子吸收光谱法和原子荧光光谱法测定蔬菜中铅、镉、砷、汞的含量。用两种国家标准参考样品进行考察，结果表明该方法不仅简便、快捷而且分析结果可靠。并提出了该方法在蔬菜痕量元素测定中应注意的问题。     

GC-NPD investigation of the recovery of organonitrogen and organophosphorus pesticides from apple samples: The effect of the extraction solvent

Summary A gas chromatographic method employing a capillary column and a selective nitrogen/phosphorus detector (NPD) has been developed for the determination of organophosphorus (OP) and organonitrogen (NP) pesticides in horticultural samples (apples). The separation of sixteen pesticides and the internal standard was performed in thirteen minutes. The analytical characteristics of the method, including linear response ranges, detection limits, and reproducibility, have been studied using a 11 mixture of ethyl acetate and xylene as extraction solvent. The possibility of mutual interference between pesticides has also been studied. A procedure for the quantitative extraction of the sixteen pesticides from apple samples has also been developed; for fifteen of the pesticides recoveries >85% were obtained after 90 minutes extraction. The effect of different solvents both on recovery and on the sensitivity of the subsequent chromatography were also investigated. It was found that the sensitivity required must be considered when the solvent for sample treatment is selected.     

Dispersion‐assisted quick and simultaneous extraction of 30 pesticides from alcoholic and non‐alcoholic drinks with the aid of experimental design

The presence of pesticides in food items and beverages is a big threat to humankind, and their quantitative estimation with high precision and accuracy is always a challenge for analytical chemists. Hence, a simple and rapid method is proposed for the simultaneous determination of 30 pesticides in beverages (alcoholic and non‐alcoholic drinks). The proposed method hyphenated with triple quadrupole liquid chromatography mass spectrometry has only 2 min chromatographic runtime for the analysis of all the pesticides. All the factors affecting the extraction yield have been optimized using an experimental design; and under optimized conditions, the developed method has been validated. The detection limits for all the pesticides were in the range of 0.001–0.348 μg/L with good linearity in the concentration range of 0.01–80.0 μg/L. The coefficient of determination was in the range of (R²) ≥ 0.977 to 0.999 for all the pesticides. The method was also checked for the precision of the relative standard deviation, which was below 4.75 (intra‐day) and 8.96% (inter‐day). The recovery of the method was 92–138%.     

Fast analysis of quaternary ammonium pesticides in food and beverages using cation‐exchange chromatography coupled with isotope‐dilution high‐resolution mass spectrometry

A fast separation based on cation‐exchange liquid chromatography coupled with high‐resolution mass spectrometry is proposed for simultaneous determination of chlormequat, difenzoquat, diquat, mepiquat and paraquat in several food and beverage commodities. Solid samples were extracted using a mixture of water/methanol/formic acid (69.6:30:0.4, v/v/v), while liquid samples were ten times diluted with the same solution. Separation was carried out on an experimental length‐modified IonPac CS17 column (2 × 15 mm²) that allowed the use of formic acid and acetonitrile as mobile phase. Detection limits for food and beverage matrices were established at 1.5 μg/L for chlormequat, difenzoquat and mepiquat, and 3 μg/L for diquat and paraquat, while for drinking water a pre‐analytical sample concentration allowed detection limits of 9 and 20 ng/L, respectively. Precision, as repeatability (RSD%), ranged from 0.2 to 24%, with a median value of 6%, and trueness, as recovery, ranged from 64 to 118%, with a median value of 96%. The method developed was successfully applied to investigate the presence of herbicide residues in commercial commodities (mineral water, orange juice, beer, tea, green coffee bean, toasted coffee powder, cocoa bean, white corn flour, rice and sugar samples).     

Study of the Electrochemical Behavior and Sensitive Detection of Pesticides Using Microelectrodes Allied to Square‐Wave Voltammetry

This work describes the application of gold and carbon fiber microelectrodes allied to square‐wave voltammetry for the study of the electrochemical behavior of the organophosphorous insecticides (methyl parathion and dichlorvos) and bipyridilium herbicides (paraquat and diquat), and the development of the sensitive methodology for their analytical determinations in natural water samples. The microelectrodes were lab‐made constructed and their electrochemical behavior was characterized by measuring the electrochemical response with a solution of potassium ferricyanide. The experimental and voltammetric conditions to obtain the best analytical signal, in terms of intensities and profile of the peak voltammetric, for four pesticides were optimized and the results were used to evaluate the type of the electrochemical redox process and to appraise the number of electrons covered in each reduction process that occurred for pesticides and also, to propose a possible redox mechanism for a reduction process of pesticides at microelectrodes. Analytical curves were constructed and presented the linear relationships between the peak currents and the concentration of pesticides, for this, the detection limits for pure water (laboratory samples) for four pesticides were calculated and presented values under 15 μg L^?1, lower than maximum limit for drinking water (100 μg L^?1) permitted by Brazilian Council for groundwater, indicating that the methodology could be employed to analyze those pesticides in natural water samples.     

Determination of pyrethroid,organophosphate and organochlorine pesticides in water by headspace solid-phase microextraction

Simultaneous determination of pyrethroid, organophosphate (OP) and organochlorine (OC) pesticides in water was achieved with headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-electron-capture detection (GC-ECD). The parameters affecting HS-SPME of pesticides from water were optimized, including extraction temperature, sample and headspace volumes, and sodium chloride amounts. The effects of desorption temperature, desorption time, and position of the fibre in the GC inlet were also investigated. Extraction temperature was the most important factor affecting the recoveries of analytes, and the optimized temperature was 96°C. The addition of salt did not increase extraction efficiencies of the pesticides from the water. The optimized desorption conditions in the GC were as follows: desorption time of 10?min; desorption temperature of 260°C; and a 2?cm position of the fibre in the inlet. The method detection limits were in the low-ng/L level with a linearity range of 50–1000?ng/L for the OCs, 50–5000?ng/L for the OP, and 50–20?000?ng/L for the pyrethroids. These data demonstrated that HS-SPME is a sensitive method for the determination of pyrethroid, OC, and OP pesticides in water.     

Determination of Organochlorine Pesticides Residue in Ginseng Root by Orthogonal Array Design Soxhlet Extraction and Gas Chromatography

Organochlorine pesticides are known to enter plant products from contamination via spillage and volatilization of the residues from pesticide-treated soils or storage. A method involving four-factor-three-level orthogonal array design including extracting solvent component, particle size, solvent overflow recycle and time needed for the optimization of extracting nine organochlorine pesticides from ginseng root was developed using Soxhlet extraction followed by capillary gas chromatography–electron capture detection and mass spectrometric confirmation. The extraction conditions were optimized from the experimental data. Relationship between the bioaccumulation of benzenehexachloride isomers and their polarity is discussed based on experimental results.     

Accurate and sensitive determination of selected hormones,endocrine disruptors,and pesticides by gas chromatography–mass spectrometry after the multivariate optimization of switchable solvent liquid‐phase microextraction

Switchable solvent liquid‐phase microextraction was combined with gas chromatography and mass spectrometry to improve the sensitivity and accuracy for the determination of selected endocrine disruptors, pesticides, and hormones. The extraction method was used to complement gas chromatography with mass spectrometry by preconcentrating analytes for trace determinations. A Box–Behnken experimental design was used to evaluate the main variables and their interaction effects, and optimum parameters were selected based on the model of experimented results. Application of optimum extraction conditions to mixed standard solutions yielded limits of detection and quantitation values between 0.20–13 and 0.90–46 ng/mL, respectively. The accuracy and the applicability of the developed method was checked in tap water and two different wastewater samples by spiked recovery tests. The percent recoveries recorded for the analytes were between 91 and 110%, and percent relative standard deviation values were all below 10%. The results indicate that the method can be used for the accurate and sensitive determination of these analytes in the presented matrixes.     

Dispersive solid‐phase extraction for the determination of trace organochlorine pesticides in apple juices using reduced graphene oxide coated with ZnO nanocomposites as sorbent

In this work, reduced graphene oxide coated with ZnO nanocomposites was used as an efficient sorbent of dispersive solid‐phase extraction and successfully applied for the extraction of organochlorine pesticides from apple juice followed by gas chromatography with mass spectrometry. Several experimental parameters affecting the extraction efficiencies, including the amount of adsorbent, extraction time, and the pH of the sample solution, as well as the type and volume of eluent solvent, were investigated and optimized. Under the optimal experimental conditions, good linearity existed in the range of 1.0–200.0 ng/mL for all the analytes with the correlation coefficients (R ²) ranging from 0.9964 to 0.9994. The limits of detection of the method for the compounds were 0.011–0.053 ng/mL. Good reproducibilities were acquired with relative standard deviations below 8.7% for both intraday and interday precision. The recoveries of the method were in the range of 78.1–105.8% with relative standard deviations of 3.3–6.9%.     

Application of fabric phase sorptive extraction with gas chromatography and mass spectrometry for the determination of organophosphorus pesticides in selected vegetable samples

In the present work, a high‐efficiency and solvent minimized microextraction technique, fabric phase sorptive extraction followed by gas chromatography and mass spectrometry analysis is proposed for the rapid determination of four organophosphorus pesticides (terbufos, malathion, chlorpyrifos, and triazofos) in vegetable samples including beans, tomato, brinjal, and cabbage. Fabric phase sorptive extraction combines the beneficial features of sol‐gel derived microextraction sorbents with the rich surface chemistry of cellulose fabric substrate, which collectively form a highly efficient microextraction system. Fabric phase sorptive extraction membrane, when immersed directly into the sample matrix, may extract target analytes even when high percentage of matrix interferents are present. The technique also greatly simplifies sample preparation workflow. Most important fabric phase sorptive extraction parameters were investigated and optimized. The developed method displayed good linearity over the concentration range 0.5–500 ng/g. Under optimum experimental conditions, the limits of detection were found in the range of 0.033 to 0.136 ng/g. The relative standard deviations for the extraction of organophosphorus pesticides were < 5%. Subsequently, the new method was applied to beans, tomato, brinjal, and cabbage samples. The results from the real sample analysis indicate that the method is green, rapid, and economically feasible for the determination of organophosphorus pesticides in vegetable samples.     

Development of a matrix solid-phase dispersion method for the simultaneous determination of pyrethroid and organochlorinated pesticides in cattle feed

A matrix solid-phase dispersion (MSPD) method was developed for the simultaneous extraction of 36 common pesticides and breakdown products (mostly pyrethroids and organochlorines) in cattle feed. Different parameters affecting the extraction efficiency (such as dispersing phase, clean-up adsorbent and elution volume) were investigated. The experimental procedure was optimized using a multivariate statistical approach and the final analyses were carried out by GC-muECD. Several protocols for extract purification were also studied. As far as we know, this is the first application of MSPD for the extraction of most of the target pesticides from animal feed. Using the optimized extraction conditions, the method was validated in terms of accuracy, and precision (within-a-day and among-days), using a certified reference material (CRM 115) as well as spiked cattle feedingstuffs at different concentration levels. A matrix effect study was also carried out using various real samples. The recoveries were satisfactory (>75% in most cases) and the quantification limits, at the sub-ngg(-1) or low-ngg(-1) level, complied with the regulated maximum residue levels (MRLs) in animal feed and in main crops used in the preparation of cattle feeding materials. Finally, the MSPD-GC-muECD methodology was applied to the analysis of real cattle feed samples collected in farms of dairy cattle from NW Spain.