Analysis of pyrethroids on grains

Two general procedures are outlined for residue determination of pyrethroid derivatives of chrysanthemic acid on wheat, wheat milling fractions, polished rice, maize, sorghum, oats and barley. Although limits of detection ranged upwards from 0.02 μg, residues in the range 0.1–4 ppm were readily analyzed on inexpensive equipment after suitable clean-up procedures. Wheat treated some months before analysis with bioresmethrin was analysed by the two general procedures for derivatives of chrysanthemic acid, and also by two procedures specific for analysis of bioresmethrin. Results from all four procedures were comparable. One of the procedures for identification of chrysanthemic acid also enabled identification of pyrethroid derivatives of chrysanthemum dicarboxylic acid and 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopro-panecarboxylic acid. Thus a wide range of commodities can be screened for the presence of commercial pyrethroids. In addition, analytical studies on individual pyrethroids can be performed by use of a general method.     

辣椒红色素提取方法的研究进展

综述了辣椒红色素提取方法的研究进展,主要介绍了溶剂法、超声波提取法、微波辅助提取法、超临界流体萃取法、酶法、分子蒸馏法以及硅胶柱层析法的提取技术,为辣椒红色素的进一步研究和开发提供参考依据。     

Occurrence and potential sources of pyrethroid insecticides in stream sediments from seven U.S. metropolitan areas

A nationally consistent approach was used to assess the occurrence and potential sources of pyrethroid insecticides in stream bed sediments from seven metropolitan areas across the United States. One or more pyrethroids were detected in almost half of the samples, with bifenthrin detected the most frequently (41%) and in each metropolitan area. Cyhalothrin, cypermethrin, permethrin, and resmethrin were detected much less frequently. Pyrethroid concentrations and Hyalella azteca mortality in 28-d tests were lower than in most urban stream studies. Log-transformed total pyrethroid toxic units (TUs) were significantly correlated with survival and bifenthrin was likely responsible for the majority of the observed toxicity. Sampling sites spanned a wide range of urbanization and log-transformed total pyrethroid concentrations were significantly correlated with urban land use. Dallas/Fort Worth had the highest pyrethroid detection frequency (89%), the greatest number of pyrethroids (4), and some of the highest concentrations. Salt Lake City had a similar percentage of detections but only bifenthrin was detected and at lower concentrations. The variation in pyrethroid concentrations among metropolitan areas suggests regional differences in pyrethroid use and transport processes. This study shows that pyrethroids commonly occur in urban stream sediments and may be contributing to sediment toxicity across the country.     

Residues of insecticides and fungicides on Ontario-grown vegetables, 1986-1988

Between 1986 and 1988, 433 composite vegetable samples representing 16 commodities were collected from farm deliveries to the marketplace in Ontario, Canada. All samples were analysed for insecticides and fungicides. The analyses included organochlorine, organophosphorus, synthetic pyrethroid, and N-methylcarbamate insecticides and dithiocarbamate, dicarboximide, and organochlorine fungicides. The commodities tested included asparagus, beans, carrots, celery, cole crops, cucumbers, lettuce, onions, peppers, potatoes, radishes, rutabagas and tomatoes. In 64% of samples, no pesticide residues were identified to the limits of detection which ranged from 0.005 to 0.05 mg/kg. A further 22% had combined insecticide and fungicide residues below 0.1 mg/kg. Most of the positive findings were a fraction of the Maximum Residue Limit permitted for each commodity under the Canadian Food and Drugs Act and Regulation. Three samples (0.7%) had residues that exceeded the MRL. These involved diazinon and parathion on celery and chlorothalonil on peppers. While some commodities had no detectable residues others had measurable residues of up to three separate pesticides. The most were found on celery, lettuce and field tomatoes.     

现代萃取技术及应用

对超临界萃取、微波萃取、超声波萃取、超高压萃取的工作原理、特点及应用现状进行了叙述,以期为该领域的生产和研究工作者提供参考。     

基质固相分散-气相色谱法测定胡萝卜中百菌清和拟除虫菊酯类农药

建立了毛细管气相色谱法同时分析胡萝卜中百菌清和5种拟除虫菊酯类农药的方法。样品以乙酸乙酯为洗脱剂经基质固相分散(matrix solid-phase dispersion,MSPD)提取和净化,DB-5毛细管柱分离,采用GC-μECD分析、外标法定量。样品加标回收率为80.5%～107.6%,相对标准偏差小于7%,方法检出限为0.003～0.006mg/kg。该方法简便、快速、灵敏、准确,符合蔬菜中百菌清和拟除虫菊酯类农药检测的要求。     

Insecticide resistance and synergism in Brazilian populations of Sitophilus zeamais (Coleoptera: Curculionidae)

Insecticide resistance to three organophosphate (chlorpyrifos-methyl, malathion and pirimiphos-methyl) and three pyrethroid (cypermethrin, deltamethrin and permethrin) insecticides was surveyed in nine field-collected populations of the maize weevil from six Brazilian States and contrasted with a standard susceptible population and a DDT and pyrethroid resistant population. Bioassay tests were carried out in glass vials (20 ml) impregnated with dried insecticide residue and the resistant populations were recognized by using discriminating concentrations established from LC₉₅s estimated for a standard susceptible population. Four field-collected populations had reduced susceptibility to cypermethrin (64-77% mortality) and to chlorpyrifos-methyl (76-77% mortality). All populations were susceptible to malathion and pirimiphos-methyl and only the DDT and pyrethroid resistant check showed resistance to all pyrethroids. Concentration-mortality curves showed non-significant levels of insecticide resistance in the field-collected populations and moderate (10-100-fold) to very high levels (>1000-fold) of resistance to pyrethroids in the DDT and pyrethroid resistant population. Results from insecticide bioassays with synergists (diethyl maleate, piperonyl butoxide, and triphenyl phosphate) suggested a major involvement of esterase as the cypermethrin resistance mechanism, while no clear result was obtained for chlorpyrifos-methyl. Synergism results provide support for target site resistance to pyrethroids in the DDT and pyrethroid resistant population used in this study.     

Antioxidant Compounds from Vegetable Matrices: Biosynthesis,Occurrence, and Extraction Systems

Natural antioxidants such as vitamin C, tocopherols and tocotrienols, carotenoids, and phenolic compounds are largely distributed in plant products. Most of them are not synthesized by human and need to be introduced with diet according to the Recommended Daily Intake (RDI). This work was aimed to give a comprehensive overview on the occurrence of these antioxidants in plants, in particular in plant foods, on the mechanisms of biosynthesis, and on conventional (liquid–liquid or solid–liquid extraction, Soxhlet) and innovative (enzymatic-assisted, pressurized fluid, supercritical fluid, ultrasound-assisted, microwave-assisted, pulsed electric field) extraction systems.     

Optimization of ultrasound-microwave synergistic extraction of prebiotic oligosaccharides from sweet potatoes (Ipomoea batatas L.)

In this study, efficient ultrasound–microwave-assisted extraction (UMAE) of prebiotic oligosaccharides from sweet potatoes (Ipomoea batatas L.) was investigated. Response surface methodology was used to optimize the extraction conditions: extraction time, ultrasonic power, and microwave power. The prebiotic effect of extracted oligosaccharides on Bifidobacterium adolescentis was also investigated. The results show that the processing conditions of UMAE for optimum the yields of prebiotic oligosaccharides from sweet potatoes (PPOS4 and PPOS5) and corresponding absorbance (OD) are 100 s extraction time, 300 W ultrasonic power, and 200 W microwave power. Under these conditions, the experimental yields of PPOS4 and PPOS5 and the corresponding OD were 1.472%, 5.476%, and 2.966, respectively, which match the predicted values well. Compared with the conventional hot-water extraction (HWE), microwave-assisted extraction (MAE), and ultrasound assisted extraction (UAE) methods, the UMAE procedure exhibited significantly high extraction efficiency (p < 0.05). Comparison of SEM images of tissues of the sweet potatoes after extractions indicate microfractures and disruption of cell walls in the potato tissues. These results confirm that UMAE has great potential and efficiency in the extraction of bioactive substances in the food and medicinal industries.Industrial relevanceUltrasound–microwave-assisted extraction is a new process technology that combines the ultrasonic and microwave methods. It makes full use of the high-energy effect of microwaves and ultrasonic cavitation. And it overcomes the shortcomings of conventional, ultrasonic, and microwave extractions. Fast, efficient extraction using this method can be realized at low temperature under ambient conditions, enhancing competition of industries to be more ecologic, economic and innovative.     

SUPERCRITICAL FLUID EXTRACTION AND DETERMINATION OF LUTEIN IN HETEROTROPHICALLY CULTIVATED CHLORELLA PYRENOIDOSA

Chlorella is a promising alternative resource of lutein, as it can be cultivated heterotrophically and efficiently in a fermentor. In this study, high density of Chlorella pyrenoidosa was achieved by fed‐batch cultivations. Lutein in Chlorella was extracted by supercritical fluid and was determined by high‐performance liquid chromatography and liquid chromatography‐mass spectrometry. The extraction degree of lutein reached 87.0% after 4‐h extraction under the optimized conditions of 50C, 25 MPa and modified CO₂ with 50% ethanol. High purity of lutein could be obtained by supercritical fluid extraction with appropriate operation parameters. The whole process developed in this study may be useful for the commercial production of lutein.     

多环芳烃脱除方法及其在维生素E油中的应用

介绍了多环芳烃（PAHs）的性质、来源和危害，详述了油、污水、土壤中多环芳烃的脱除方法：物理法（包括萃取法、吸附法、层析法及人造纤维富集法等）、化学反应法、生物反应法、化学-生物降解法等，比较了各种脱除方法的优缺点。分析了维生素E油中的PAHs的来源。实验结果显示，硅胶柱层析法、微波萃取法、人造纤维bluerayon吸附等方法对维生素E油中PAHs的脱除有较好的效果。     

Iron enrichment of whole potato tuber by vacuum impregnation

The effect of vacuum time, restoration time, steam-cooking and storage at 4 °C on the iron content of vacuum-impregnated (VI) whole potato was evaluated. Whole potato tubers were immersed in a 0.4 g/100 g iron (ferric pyrophosphate) solution. Vacuum pressure of 1000 Pa was applied for 0–120 min, and atmospheric pressure restoration for 0–4 h. The result indicated that the iron content of VI potatoes increased with vacuum and restoration time; 1 h vacuum-treatment potatoes provided 6.4 times higher iron content compared to raw potatoes, and 3 h restoration time supplied 6.4 times higher iron content (>4.1 mg/100 g fr.wt.) compared to raw potatoes. Moreover, VI-cooked unpeeled or peeled potatoes had 6 times higher iron content than un-VI-cooked unpeeled or peeled potatoes. European daily potato consumption (260 g) of the VI-cooked unpeeled and peeled potatoes provided adult men with 93–104% and 67–90% of the recommended daily allowance (RDA) of iron, respectively. Also, the daily potato consumption of the unpeeled and peeled potatoes could supply adult women with 43–48% and 31–41% of the RDA, respectively. This study indicated that VI treatment of whole potato was useful for enriching the iron content.     

水果中26种有机氯及拟除虫菊酯农药残留GC-ECD测定

利用气相色谱(GC)建立了水果中26种有机氯农药同时测定的方法。试样中农药残留在超声波振荡条件下用乙腈提取,经PSA、C18净化,GC-电子捕获检测器(ECD)检测。方法的检出限为0.001～0.005mg/kg,回收率为84.5%～104.5%,相对标准偏差为1.1%～6.7%。该方法的灵敏度、准确度和精密度均符合农药残留测定的技术要求。     

两种方法提取丢糟中酯类成分的比较研究

采用CO2超临界萃取法和60％酒精热浸提法提取丢糟中的酯类物质,气相色谱分析结果表明：①两种方法均未能提取丢糟中的乙酸乙酯;②CO2超临界萃取法能够提取丢糟中的乳酸乙酯、己酸乙酯、丁酸乙酯和戊酸乙酯,而酒精热浸提法只能提取出乳酸乙酯和戊酸乙酯,且后者乳酸乙酯的含量达275．9285mg／100g,远远超过了前者的11．8955mg／100g。因此,提取丢糟中主要酯类成分,CO2超临界萃取法优于60％（v／v）酒精热浸提法。     

蜂胶黄酮类化合物提取工艺参数优化

基于合理的实验工艺条件的选择和实验设计,利用了RSA响应面分析方法对以乙醇溶液为夹带剂,利用超临界流体CO2萃取蜂胶黄酮类化合物的工艺参数进行优化。结果表明:各响应因子萃取压力、乙醇浓度和固液比的最佳工艺参数分别为:25MPa、95%和6:1, 同时丰富了蜂胶类黄酮化合物的超临界流体CO萃取工艺优化设计。     

基于电化学技术的Ⅱ型拟除虫菊酯分子印迹膜的研制

拟除虫菊酯类农药残留造成的安全问题已受到越来越广泛的关注,开发快速检测技术可为农副产品中拟除虫菊酯类农药残留的监控提供技术支持。本实验以邻氨基酚为功能单体,以Ⅱ型拟除虫菊酯农药结构类似物间苯氧基苯甲酸为模板分子,采用循环伏安法电聚合技术在玻碳电极表面聚合形成可检测含间苯氧基苯甲酸结构的Ⅱ型拟除虫菊酯农药的分子印迹膜,用于Ⅱ型拟除虫菊酯类农药的检测研究。5 min可完成对农药的响应,其响应电流变化值与一定浓度范围内的溴氰菊酯、氰戊菊酯、甲氰菊酯、氯氟氰菊酯呈良好的线性关系,相关系数r分别为0.991、0.992、0.992、0.990,精密度分别为2.20%、2.80%、2.50%、2.12%,检出限在0.01mg/kg~0.30 mg/kg之间。对加标红桔、贡桔和椪柑样品进行检测,准确性高。     

Application of enzyme-linked immunosorbent assay for quantification of the insecticides imidacloprid and thiamethoxam in honey samples

An enzyme-linked immunosorbent assay (ELISA) was used for the determination of residues of imidacloprid and thiamethoxam insecticides in honey after simple dilution of the samples without either extraction or cleanup. The ELISA enabled accurate determination of imidacloprid and thiamethoxam down to limits of 20 and 5 ng g^?1 in honey, respectively. Average recoveries of imidacloprid and thiamethoxam from the fortified honey samples were 90–120 and 96–122%, and coefficients of variation ranged 5–12 and 3–15%, respectively. The results from the ELISA agreed well with those by liquid chromatography–mass spectrometry (LC–MS) for the insecticide-spiked samples, with a correlation coefficient (r ²) of 0.96 and a regression coefficient (slope) of 1.03. The results indicate that ELISA is a suitable tool for the quantification of imidacloprid and thiamethoxam in honey.     

YIELD AND QUALITY OF ONION FLAVOR OIL OBTAINED BY SUPERCRITICAL FLUID EXTRACTION AND OTHER METHODS

Methods of extraction of onion flavor oil were studied including supercritical fluid extraction using carbon dioxide (CO₂), liquid CO₂ extraction and steam distillation-solvent extraction. The effect of using entrainers with supercritical fluid extraction was also studied. The yield and the quality of onion extracts obtained from the different methods were compared. The maximum yield of 0.0324% was obtained by supercritical CO₂ extraction at 3600psi (24.5 MPa), 37C at a CO₂ flow rate of 0.5 L/min. Ethyl alcohol used as entrainer enhanced the yield of onion oil over that obtained by supercritical CO₂ experiment without entrainer at the CO2flow rate of 1.0 L/min. Gas chromatography and combined gas chromatography-mass spectrometry of the extracts indicated that the flavor profiles were different for extracts obtained by different methods. Supercritical and liquid CO₂ extracts had fresh onion-like flavor as opposed to a cooked flavor of the extract obtained by steam distillation-solvent extraction.     

固相萃取-气相色谱法检测蔬菜中8种菊酯类 农药残留

目的建立一种固相萃取-毛细管柱气相色谱方法,可以同时检测蔬菜中8种菊酯类农药残留。方法蔬菜样品匀浆后,经正己烷/丙酮(V:V=50:50)提取,Florisil固相萃取柱净化,HP-5毛细管气相色谱柱进行分离,GC-ECD进行定性及定量分析。结果 8种菊酯类农药残留的色谱图分离效果良好,线性相关系数均大于0.995,方法检出限在0.0025~0.02 mg/kg之间。8种菊酯类农药的添加水平为0.025~2 mg/kg,回收试验表明该方法平均回收率在73.6%~97.0%之间,相对标准偏差小于5%。结论该方法样品处理简单、仪器配置要求较低、净化效果好、易于推广使用,适合蔬菜中多种菊酯类农药残留的检测和安全监控。     

超声辅助浊点萃取-液相色谱-串联质谱法测定蔬菜中天然VK同系物

通过优化超声辅助提取和微波辅助浊点萃取方法,建立超声辅助浊点萃取-液相色谱-串联三重四极杆质谱法同时测定蔬菜中天然VK同系物叶绿醌（phylloquinone,PK）和四烯甲萘醌（menaquinone-4,MK-4）的检测方法。蔬菜样品经乙腈超声辅助提取分离出分析物,并通过微波辅助浊点萃取,以甲酸铵溶液-甲醇作为流动相梯度洗脱,采用电喷雾离子源正离子多反应监测模式测定,外标法定量。结果显示,超声辅助浊点萃取的优化条件为1.5?g样品加入乙腈体积2?mL、超声提取、提取液中氯化钠添加量0.15?g、萃取溶剂采用Triton?X-45、萃取溶剂体积50?μL。2?种VK同系物PK和MK在1.0～500.0?ng/mL范围线性良好,相关系数均大于0.997?0,PK和MK的方法检出限分别为1.0?ng/g和0.8?ng/g。加标含量为40、80、120?ng/g的PK和MK加标回收率在94.5%～106.2%范围内,方法日间和日内重复性相对标准偏差不大于10%,根茎类蔬菜中未检出天然VK,而绿叶蔬菜均仅检测到PK,含量在96.2～1?704.5?ng/g之间,其中菠菜中PK含量最高。