Comparison of sample preparation methods combined with gas chromatography with electron‐capture detection for the analysis of multipesticide residues in lotus seeds

Sample preparation is always the major bottleneck in analytical chemistry for the determination of pesticide residues. Different sample preparation methods have been proposed due to the wide variety of pesticides used and the inherent complexity of the matrices. In this study, different sample preparation methods including SPE, matrix solid‐phase dispersion, the quick, easy, cheap, efficient, rugged, and safe method, and a one‐step completion method were compared and evaluated for extracting pesticides from lotus seeds. Analysis was carried out using GC with electron‐capture detection. The results showed that good recoveries for tested pesticides were obtained by using Florisil in the four methods, and the extraction efficiency of the one‐step completion method was superior to the other three methods. The one‐step completion method was confirmed to have good linearity, reproducibility, stability, and recovery for the detection of 36 pesticides in lotus seed samples. The data collected from this study are expected to prove useful in regulating the concentration of the residues in lotus seeds, as well as in protecting human health from the hazards posed by these residues.     

Determination of benzotrifluoride derivative compounds in groundwater

Two simple analytical methods for the simultaneous determination and quantification of benzotrifluoride and eight chlorinated, amino and nitro benzotrifluoride derivatives in groundwater are proposed. Benzotrifluoride, 4-chlorobenzotrifluoride, 2,4-dichlorobenzotrifluoride and 3,4-dichlorobenzotrifluoride, were extracted by Purge-and-Trap on the basis of their volatile properties, while 3-aminobenzotrifluoride, 4-nitrobenzotrifluoride, 3-amino-4-chlorobenzotrifluoride, 3-nitro-4-chlorobenzotrifluoride and 4-chloro-3,5-dinitrobenzotrifluoride extractions were done with an automated SPE system. The analytical separations and detections were performed with two different GC systems, both equipped with single quadrupole mass spectrometer as detector. The LOD ranges for the two methods were 0.002–0.005 μg L⁻¹ and 0.01–0.07 μg L⁻¹, respectively. Both extraction methods were developed using spiked Milli-Q water and were then demonstrated with groundwater samples collected during autumn 2008. The areas of groundwater collection were polluted due to an episode of improper industrial soil disposal and consequent leakage of aliphatic and aromatic, fluorinated chemicals into the groundwater. This work eventually revealed the presence of several benzotrifluoride compounds most of them, like dichloro- and amino-derivatives, never been reported as environmental contaminants.     

磁性复合材料在固相萃取食品中环境类雌激素的应用进展EI北大核心CSCD

环境类雌激素作为食品中一类典型的污染物,严重影响人体内分泌系统的功能与代谢。磁性固相萃取因其简洁高效、富集倍数高、适用范围广等优点,已被广泛应用于食品中环境类雌激素的富集检测。Fe_(3)O_(4)纳米粒子作为经典的磁固相萃取材料,易于形成大分子团聚物,影响其选择吸附性能,限制了磁固相萃取技术在食品中环境类雌激素的痕量分析。新兴的磁性复合材料可有效地解决上述问题,已成为磁固相萃取技术的研究热点之一。本文综述了近5年来新兴的磁性聚合物复合材料、磁性碳基复合材料和磁性金属-有机骨架复合材料在食品中环境类雌激素富集检测的应用进展。     

Ultrasound-assisted polysaccharide extraction from Cercis chinensis and properites,antioxidant activity of polysaccharide

The purpose of the study was to improve the extraction of polysaccharide from the leaves of Cercis chinensis Bunge using ultrasound, and compare the difference between boiling and ultrasound extraction in terms of polysaccharide content, monosaccharide compounds, and evaluate how the factors affected the bioactivity. The best conditions, according to the single factor experiments and the Box-Bohnken design (BBD), were an intensity of ultrasound of 180 W, duration of extraction of 40 min, proportion of water to material of 15:1 (g/g), and a higher polysaccharide yield of 20.02 ± 0.55 (mg/g) than in boiling extraction (16.09 ± 0.82 mg/g). The antioxidative experiment suggested the polysaccharide by ultrasound exhibited higher DPPH, hydroxyl radical scavenging capacities, and reducing power at 1.2–1.4 mg/mL, which was superior to the boiling polysaccharide. Further analysis showed that the ultrasonic purified polysaccharides like Gla, N-Glu, and GluA contained more total sugar and uronic acids than the boiling method did. This may indicate that the ultrasonic isolation of the polysaccharides increase the antioxidant activity of the polysaccharides.     

CMPO-离子液体萃取分离铀(VI)体系的电化学性质

研究了辛基(苯基)-N,N-二异丁基胺甲酰基甲基氧化膦(CMPO)-离子液体(IL)从硝酸铀酰水溶液中萃取铀(VI)的电化学行为, 离子液体(IL)为1-丁基-3-甲基咪唑双三氟甲基磺酰亚胺盐(C₄mimNTf₂). 用等摩尔系列法测得萃取过程中CMPO与U(VI)形成摩尔比为3:1的配合物. 用循环伏安法研究了萃取液中U(VI)-CMPO配合物的电化学性质, 结果表明, 在C₄mimNTf₂中U(VI)-CMPO 配合物经过准可逆还原生成U(V)-CMPO 配合物, U(VI)/U(V)电对的表观氧化还原电势(E^Θ, vs Fc/Fc⁺)为(?0.885±0.008) V. 对萃取液进行控制电位电解, 发现在铂片上有沉淀析出. X射线光电子能谱(XPS) 测试结果表明, 沉积物中只含有U(VI)、U(IV)和氧, 而CMPO和C₄mimNTf₂没有被夹带析出.     

Extraction of Residues of Dyfonate-ring-14C from Soil

Abstract

Residues of Dyfonate-ring-¹⁴C were extracted from a clay loam soil with various solvents under a variety of conditions. Recovery of radioactivity from the soil was not related to the polarity (dipole moment) or the dielectric constant of the solvents. Commonly used solvents such as acetone, methanol, ethanol, and hexane/acetone (1:1) extracted only 28, 44, 27, and 25%, respectively, of the residues from the air-dried soil. The extraction efficiencies were increased to 46, 60, 54, and 49%, respectively, when 20% water was added to the soil prior to extraction with these solvents. The amount of water added to the soil and time of contact with water also affected the recovery of radioactivity from the soil. Any of the solvents or methods investigated failed to recover more than 60% of the radioactivity in the soil, indicating that residues of Dyfonate were strongly bound to the soil and were difficult to recover.     

Ge(Ⅳ)与Ga(Ⅲ)、Pb(Ⅱ)、Ce(Ⅲ)、V(Ⅴ)和W(Ⅵ)的析相绿色萃取分离和富集

用光度法研究了正丙醇-碘化钾-水体系萃取分离锗的行为,探讨了Ge（Ⅳ）与一些金属离子的分离条件。实验表明.当溶液中正丙醇、碘化钾和硫酸铵的浓度分别为30%（V/V）、8.0×10^-3mol/L和0.20g/mL时,Ge（Ⅳ）与Ga（Ⅲ）、Pb（Ⅱ）、Ce（Ⅲ）、V（Ⅴ）和W（Ⅵ）可定量分离。     

固相萃取-高效液相色谱法测定烟叶中吡虫啉农药残留量

建立了固相萃取-高校液相色谱法测定烟叶中吡虫啉农药残留量的方法。样品用乙腈提取,弗罗里硅土固相萃取柱净化.梯度洗脱方式分离,DAD二极管阵列检测器检测。吡虫啉加标回收率为87.83%—94.80%,相对标准偏差为1.64%,检出限为0.01μg/g。该方法灵敏、准确,适用烟草中吡虫啉农药残留的分析。     

超声波法提取啤酒花中总多糖的工艺

采用超声波法提取啤酒花中总多糖.采用正交试验设计,以总多糖含量为评价指标进行实验.最佳提取工艺为:超声提取2次,加12倍量的水,每次40min,超声功率为160W.本提取工艺合理,啤酒花中总多糖提取率较高.     

正交试验法优选山绿茶中乌苏酸提取工艺

筛选山绿茶中乌苏酸的最佳提取工艺。采用正交设计L9(34)考察液固比、提取时间、乙醇浓度和提取次数4个因素,用高效液相色谱法测定山绿茶中乌苏酸的含量。山绿茶中乌苏酸的最佳提取工艺为A2B3C3D1,即选择液固比(mL/g)10∶1、提取时间4h、乙醇浓度90%、提取次数1次。本法工艺合理,质量稳定,适宜于工业化生产。