Pesticides in the atmosphere across Canadian agricultural regions

The Canadian Atmospheric Network for Currently Used Pesticides (CANCUP) was the first comprehensive, nationwide air surveillance study of pesticides in Canada. This paper presentsthe atmospheric occurrence and distribution of pesticides including organochlorine pesticides (OCPs), organophosphate pesticides (OPPs), acid herbicides (AHs), and neutral herbicides (NHs) during the spring to summer of 2004 and 2005 across agricultural regions in Canada. Atmospheric concentrations of pesticides varied within years and time periods, and regional characteristics were observed including the following: (i) highest air concentrations of several herbicides (e.g., mecoprop, triallate, and ethalfluralin) were found at Bratt's Lake, SK, a site in the Canadian Prairies; (ii) the west-coast site at Abbotsford, BC, had the maximum concentrations of diazinon; (iii) the fruit and vegetable growing region in Vineland, ON, showed highest levels for several insecticides including chlorpyrifos, endosulfan, and azinphos-methyl; (iv) high concentrations of atrazine and metolachlor were measured at St. Anicet, QC, a corn-growing region; (v) the Kensington site in PEI, Canada's largest potato-producing province, exhibited highest level of dimethoate. Analysis of particle- and gas-phase fractions of air samples revealed that most pesticides including OCPs, OPPs, and NHs exist mainly in the gas phase, while AHs exhibit more diversity in particle-gas partitioning behavior. This study also demonstrated that stirred up soil dust does not account for pesticides that are detected in the particle phase. The estimated dry and wet deposition fluxes indicate considerable atmospheric inputs for some current-use pesticides (CUPs). This data set represents the first measurements for many pesticides in the atmosphere, precipitation, and soil for given agricultural regions across Canada.     

Photocatalytic degradation of selected s-triazine herbicides and organophosphorus insecticides over aqueous TiO2 suspensions

The photocatalytic degradation of selected s-triazine herbicides and organophosphorus insecticides was carried out in aqueous TiO2 suspensions under simulated solar light. The tested herbicides from the s-triazines group were atrazine, propazine, cyanazine, prometryne, and irgarol. The tested insecticides from the organophosphorus group were ethyl parathion, methyl parathion, ethyl bromophos, methyl bromophos, and diclofenthion. Degradation kinetics followed first-order reaction and has been monitored through gas chromatography. The degradation was fast with half-lives varying from 10.2 to 38.3 min depending on the nature and the structure of compounds. The generated transformation products (TPs) were formed via oxidation, dealkylation, and dechlorination for s-triazines and via oxidation and photohydrolysis for organophosphates. The TPs of irgarol, bromophos, and dichlofenthion were identified using solid-phase extraction (SDB-disks) and GC-MS techniques, and possible degradation routes were proposed showing similar degradation pathways as for other triazines and organophosporus pesticides. This work points out to the necessity of extended knowledge of the successive steps in a solar-assisted detoxification process.     

Diffusion of organophosphorus insecticides in soils

Diffusion of disulfoton and dimethoate in a silt loam soil was studied over a range of concentrations and moisture contents. Apparent diffusion coefficients were calculated from the distribution of insecticide in a column of soil after diffusion from one half of the column to the other for a known time. The distribution was determined by slicing the column into narrow; sections using a specially constructed diffusion cylinder. Diffusion coefficients varied little with concentration for both insecticides, but increased rapidly with increasing moisture content for dimethoate from 3.31 × 10^?8 cm²/sec at 10% volumetric moisture content to 1.41 × 10^?6 cm²/sec at 43% moisture content. In contrast, for disulfoton which is more volatile, less soluble and more strongly sorbed than dimethoate, diffusion coefficients were smaller (2.83 × 10^?8 cm²/sec at 41% moisture content) but did not change much as the soil became drier (2.74 × 10^?8 cm²/sec at 8 % moisture content). The influence of partition between solid, solution and vapour phases in the soil and of the geometry of the pathway-through the soil pores on the apparent diffusion coefficient is discussed. The likely behaviour of other pesticides is considered in the light of these results.     

Simultaneous determination of N-methylcarbamate pesticides and their metabolites in agricultural products

We investigated the determination of N-methylcarbamate pesticides and their metabolites in agricultural products by HPLC with post-column fluorescence detection after clean-up with an SPE cartridge. The homogenate of agricultural products was extracted with acetone. The crude extract was partitioned between 5% sodium chloride solution and dichloromethane, and the dichloromethane layer was concentrated to dryness. The residue was dissolved with a mixture of acetone and n-hexane, and purified by using Supelclean ENVI-Carb SPE, Bond Elut Extraction Cartridge PSA and SAX in series with a mixture of acetone and n-hexane. N-Methylcarbamate pesticide was analyzed by HPLC with post-column reaction and fluoresce detection. N-Methylcarbamate pesticide in citrus fruits and various kinds of agricultural products could be analyzed accurately by the presented method. Recoveries of N-methylcarbamate pesticides added to several agricultural products at the level of 0.10 ppm were mostly in the range of 60-110%. The limit of detection was 0.005 ppm.     

农产品中噻苯隆的残留现状、降解特点及分析方法进展

噻苯隆是一种具有生长素和细胞分裂素活性的苯基脲类植物生长调节剂,在农产品生产中合理使用可起到增加产量、改善品质的作用。但是,随着噻苯隆的大量使用,其在农产品中的残留问题逐渐显现,由于对哺乳动物存在一定的毒性风险,许多国家针对噻苯隆都制定了严格的限量标准,对噻苯隆残留降解、检验检测等方面的研究也日益增多,但缺乏对近期已有研究成果的比较系统全面的综述。本文介绍了近几年我国农产品中噻苯隆的残留现状,总结了不同农产品中噻苯隆的降解特点,综述了噻苯隆的主要检测方法,以及各方法在实际检测应用中的优缺点,并对噻苯隆今后的研究工作提出建议,旨在为农产品生产中合理规范使用噻苯隆以及建立农产品中噻苯隆快速、高效和精准的残留检测方法提供参考。     

Occurrence of salmonellae in retail chicken carcasses and their products in Spain

This study examined the incidence of Salmonella in Spanish poultry products. Samples included chicken carcasses, chicken parts (wings, legs and giblets-livers and hearts) and processed chicken products (red sausages, white sausages and hamburgers). The average detection rate was 49%, with the highest (55%) in chicken carcasses (skin) and the lowest (20%) in hamburgers. The chicken carcasses purchased in supermarkets were more contaminated (75%) than those from poulterers shops (25%). Salmonella Enteritidis, S. Poona, S. Paratyphi B and S. Worthington were isolated in 34.3%, 11.4%, 2.8% and 1.4% of the samples, respectively. One (1.4%) red sausage sample harboured two serotypes (S. Enteritidis and S. Worthington). This fact emphasizes the usefulness of subtyping several Salmonella isolates from the same sample in epidemiological studies.     

Occurrence of mycotoxins in spelt and common wheat grain and their products

Organic farming does not allow the use of conventional mineral fertilizers and crop protection products. As a result, in our experiments we chose to grow different species of cereals and to see how cereal species affect mycotoxin accumulation. This study describes the occurrence of deoxynivalenol (DON), zearalenone (ZEA) and T-2/HT-2 toxin in a survey of spelt and common wheat and their bran as well as flour. The analysis was conducted using an enzyme-linked immunosorbent assay (ELISA) method. The concentrations of DON, ZEA and T-2/HT-2 in Triticum spelta and T. aestivum were influenced by species, cereal type and year interaction. The highest concentrations of these mycotoxins were found in spelt grain with glumes, in spelt glumes and in spring wheat. These results show significantly higher concentrations of Fusarium toxins in glumes than in dehulled grain, which indicates the possible protective effect of spelt wheat glumes. The lowest DON, ZEA and T-2/HT-2 concentrations were determined in spelt grain without glumes. The research shows that it is potentially risky to produce bran from grain in which mycotoxin concentrations are below limits by European Union Regulation No. 1881/2006, since the concentration of mycotoxins in bran can be several times higher than that in grain. As a result, although bran is a dietary product characterised by good digestive properties, it can become a harmful product that can cause unpredictable health damage.     

物理技术降解农产品农药残留的研究进展

农药的使用对农业的发展发挥着重大作用,不仅可以使农产品保收、增产,还可以提升产品质量.但使用农药的同时也造成严重的农药污染以及食品安全问题.本文对可降低农产品中农药残留量的物理技术或方法进行了综述,包括光照、超声波、电离辐射、低温等离子体、超高压、洗涤、加热等,以期为相关技术的应用及提升、相关设备和产品的研发生产、农产品生产与消费安全的集成创新,提供理论依据,提高农产品食用安全性.     

牛奶中7种有机磷农药及其热降解的GC分析研究

对牛奶中的敌百虫、甲拌磷、久效磷、乐果、倍硫磷、马拉硫磷和甲基对硫磷的毛细管气相色谱检测条件改进,并研究这7种有机磷农药在的热降解.利用丙酮-乙腈(体积比为1:4)提取液萃取牛奶样品中的七种有机磷农药,程序升温毛细管气相色谱法测定,7种有机磷农药的平均回收率为78.2%～125.9%.检出限为0.006～0.02 mg/kg.80 ℃和100℃模拟加热处理牛奶样品,分析结果表明加热处理促进7种有机磷农药降解,80℃时它们的半衰期为4.8～8.6 h,而100℃时则减少至4.0-6.0 h.整体上看,倍硫磷、马拉硫磷和甲基对硫磷的稳定性较差,较容易降解.     

Occurrence of iodinated X-ray contrast media and their biotransformation products in the urban water cycle

A LC tandem MS method was developed for the simultaneous determination of four iodinated X-ray contrast media (ICM) and 46 ICM biotransformation products (TPs) in raw and treated wastewater, surface water, groundwater, and drinking water. Recoveries ranged from 70% to 130%, and limits of quantification (LOQ) varied between 1 ng/L and 3 ng/L for surface water, groundwater and drinking water, and between 10 ng/L and 30 ng/L for wastewater. In a conventional wastewater treatment plant, iohexol, iomeprol, and iopromide were transformed to >80%, while iopamidol was transformed to 35%. In total, 26 TPs were detected above their LOQ in WWTP effluents. A significant change in the pattern of ICM TPs was observed after bank filtration and groundwater infiltration under aerobic conditions. Predominately, these TPs are formed at the end of the microbial transformation pathways in batch experiments with soil and sediment. These polar ICM TPs, such as iohexol TP599, iomeprol TP643, iopromide TP701A, and iopromide TP643, were not or only partially removed during drinking water treatment. As a consequence, several ICM TPs were detected in drinking water, at concentration levels exceeding 100 ng/L, with a maximum of 500 ng/L for iomeprol TP687.     

Decay of dinitroaniline herbicides and organophosphorus insecticides during brewing of lager beer

This article examines the fate of four pesticides that can be present during the brewing of lager beer. For this purpose, malted barley was spiked at 2 mg/kg with pendimethalin and trifluralin (dinitroaniline herbicides) and fenitrothion and malathion (organophosphorus insecticides). Analyses of pesticide residues were carried out by a gas chromatograph with an electron capture detector, and their identity was confirmed by gas chromatography-mass spectrometry. Cleanup was necessary for the malt and spent grain samples. Beginning with mashing and ending with the final product 4 months later, various samples (spent grain, sweet wort, brewer wort, and beer) were taken to determine the concentration of the targeted residual pesticides during the various beer making phases. In all cases, the residual levels recorded in sweet wort sampled after the mashing phase were below the respective maximum residue limits established by Spanish legislation for barley. Significant proportions of pesticide residues (17 to 40%) were retained on the spent grain. Applying the standard first-order kinetics equation (r > 0.91), the half-lives obtained for the four compounds during the storage of the spent grain (3.5 months) varied from 138 days (fenitrothion) to 192 days (malathion and pendimethalin). Herbicide residues practically disappeared (<0.3%) after wort boiling, whereas the percentages of the remaining insecticides, fenitrothion and malathion, ranged from 3.5 to 4.3%, respectively, at this time. No residues of dinitroaniline compounds were detected in young beer, whereas there was a significant reduction in fenitrothion (58%) and malathion (71%) residues during fermentation. Lagering and filtering processes also reduced the content of the organophosphorus insecticides (33 to 37%). Finally, after the storage period (3 months), the content of fenitrothion was reduced by 75%, with malathion residues being below its detection limit.     

Sterols heating: degradation and formation of their ring-structure polar oxidation products

Cholesterol and phytosterols can be oxidised under heating conditions to give sterol oxidation products (SOPs), known by their toxic effects. This paper studied the degradation of cholesterol and three plant sterols during a 360 min heating treatment (180 °C). The formation and further degradation of SOPs was also analysed by GC-MS. Results revealed a sterol susceptibility to degradation according to the following decreasing order: campesterol≈β-sitosterol≥stigmasterol>cholesterol. The degradation curve fit (R(2)=0.907-0.979) a logarithmic model. SOPs increased their concentration during the first 5-10 min and thereafter, their degradation rate was higher than their formation rate, resulting in a decrease over time. Irrespective of the sterol from which they had derived, 7-keto derivatives presented the highest levels throughout the entire process, and also SOPs with the same type of oxidation followed a similar degradation pattern (R=0.90-0.99).     

Occurrence of antibiotic-resistant enterobacteria in agricultural foodstuffs

Antibiotic-resistant bacteria or their corresponding resistance determinants are known to spread from animals to humans via the food chain. We screened 20 vegetable foods for antibiotic-resistant coliform bacteria and enterococci. Isolates were directly selected on antibiotic-containing selective agar (color detection). Thirteen "common vegetables" (tomato, mushrooms, salad) possessed 10(4)-10(7) cfu/g vegetable of coliform bacteria including only few antibiotic-resistant variants (0-10(5) cfu/g). All seven sprout samples showed a some orders of magnitude higher contamination with coliform bacteria (10(7)-10(9) cfu/g) including a remarkable amount of resistant isolates (up to 10(7) cfu/g). Multiple resistances (up to 9) in single isolates were more common in sprout isolates. Resistant bacteria did not originate from sprout seeds. The most common genera among 92 isolates were: 25 Enterobacter spp. (19 E. cloacae), 22 Citrobacter spp. (8 C. freundii), and 21 Klebsiella spp. (9 K. pneumoniae). Most common resistance phenotypes were: tetracycline (43%), streptomycin (37%), kanamycin (26%), chloramphenicol (29%), co-trimoxazol (9%), and gentamicin (4%). The four gentamicin-resistant isolates were investigated in molecular details. Only three (chloramphenicol) resistant, typical plant-associated enterococci were isolated from overnight enrichment cultures. In conclusion, a contribution of sprouts contaminated with multiresistant, Gram-negative enterobacteria to a common gene pool among human commensal and pathogenic bacteria cannot be excluded.     

Occurrence of pathogens in raw and ready-to-eat meat and poultry products collected from the retail marketplace in Edmonton, Alberta, Canada

A total of 800 meat and poultry products were purchased from the retail marketplace in Edmonton, Alberta, Canada. The products consisted of raw ground beef, chicken legs, pork chops, and ready-to-eat fermented sausage, roast beef, processed turkey breast, chicken wieners, and beef wieners. The samples were analyzed to determine the prevalence of Shiga toxin-producing Escherichia coli, Salmonella, Campylobacter spp., and Listeria monocytogenes. Shiga toxin-producing E. coli 022: H8 was found in one raw ground beef sample. Salmonella and Campylobacter were found in 30 and 62% of raw chicken legs, respectively. L. monocytogenes was found in 52% of raw ground beef, 34% of raw chicken legs, 24% of raw pork chops, 4% of fermented sausages, 3% of processed turkey breast, 5% of beef wieners, and 3% of chicken wieners. The occurrence of pathogens in this study is similar to that in retail products in many other international locales.     

富硒农产品中硒代氨基酸形态及其在不同蛋白组分中的分布

目的：探究富硒西兰花、富硒大豆、富硒玉米、富硒大麦苗不同溶解性蛋白组分中硒代氨基酸形态及分布情况。方法：利用高效液相色谱—氢化物发生—原子荧光光谱联用技术测定4种富硒禾谷类和十字花科农产品中硒代蛋氨酸(SeMet)、硒代胱氨酸(SeCys2)、甲基硒代半胱氨酸(MeSeCys)和硒代乙硫氨酸(SeEt)含量,并分析各硒代氨基酸在清蛋白、球蛋白、醇溶蛋白和谷蛋白等不同溶解性蛋白组分中的分布特点。结果：4种富硒植物的硒代氨基酸在不同蛋白组分中的含量及分布存在显著差异(P＜0.05)。富硒大豆、富硒玉米、富硒大麦苗的有机硒以SeMet形式存在,在4类蛋白组分中分布较一致且相对含量均高于66%,不存在SeEt;富硒西兰花的有机硒主要以SeCys2和SeMet为主、MeSeCys次之,前二者在清蛋白和谷蛋白组分中的分布较一致且约占有机硒含量的36%,但在球蛋白和醇溶蛋白组分中均以SeMet存在,相对含量最高达60%,其次为SeCys2约占有机硒含量的34%。富硒西兰花中存在极少量的SeEt约占有机硒含量的5%。结论：3种禾谷类农产品(富硒大豆、富硒玉米、富硒大麦苗)的不同溶解性蛋白中均以SeMet为主;而富硒西兰花的不同溶解性蛋白则以SeMet和SeCys2为主,并且其清蛋白和谷蛋白还富含较多的MeSeCys。     

Determination of benzylaminopurine in agricultural products

A simplified method for the determination of benzylaminopurine in agricultural products by LC/MS was investigated. Benzylaminopurine in agricultural products was extracted with acetone and the extract was concentrated to below 30 mL. Buffer solution of pH 9.0 and ethyl acetate were added to the residue, and the solution was shaken. The ethyl acetate layer was evaporated to dryness, and the residue was dissolved in acetone-n-hexane (1 : 1). The solution was applied to a SAX/PSA mini-column, which was then rinsed with acetone-n-hexane (1 : 1). Benzylaminopurine was eluted with acetone-n-hexane (1 : 1) containing 1% water. The eluates were evaporated to dryness, and the residue was dissolved in 10 mmol/L ammonium acetate-methanol (1 : 1). Benzylaminopurine was analyzed by LC/MS. The MS detection was performed in the selected ion monitoring (SIM) mode, with detection of the M+H(+) ion of benzylaminopurine (m/z 226) generated by electrospray ionization (ESI). Recoveries of benzylaminopurine from 15 agricultural products were in the range of 83.1-97.2%. The limits of detection (S/N=3) of benzylaminopurine in all samples except green tea and in green tea were 0.0003 and 0.0012 microg/g, respectively.     

热烫对4种芸薹属蔬菜硫代葡萄糖苷及其吲哚族降解产物的影响

研究了热烫对甘蓝、娃娃菜、小白菜和瓢儿菜4种芸薹属蔬菜硫苷及其吲哚族硫苷降解产物的影响。结果表明,4种蔬菜硫苷含量明显不同,鲜甘蓝中总硫苷含量最高(89.73μmol/g干重),鲜瓢儿菜总硫苷含量最低(34.94μmol/g干重)。新鲜蔬菜在90℃下分别用水热烫处理20、40、60 s后,各蔬菜的硫苷含量均显著降低,热烫60 s,总硫苷物质损失71%~73%。新鲜蔬菜总吲哚族硫苷降解产物含量相近,90℃热烫20~60 s能显著提高其吲哚族硫苷降解产物含量。结果表明,热烫60 s能使4种芸薹属蔬菜的吲哚族硫苷降解产物含量增加1~5倍,有利于提高其抗肿瘤、抑菌等生理活性,可作为蔬菜烹饪预处理的手段之一。     

食品工业是农业增值的必由之路

<正> 农业是食品工业的基础,如果没有强大的农业基础,发展食品工业只能依靠进口原料,这对于目前我国的加工水平来说,显然是不行的;反之,如果没有食品工业的加工增值,农业发展即使增产也不能增收。由此可见,农业和食品工业是互相依存,紧密而不可分割的。