Determination of tricyclohexyltin hydroxide residues in apples and pears

Plictran (tricyclohexyltin hydroxide, Cy₃SnOH) residues in Stark Delicious apples and Passacrassana pears were determined. Field applications were carried out 7, 16 and 28 days before harvest. The analyses were carried out by two procedures: selective determination of the various Sn forms and determination of total Sn. The final spectrophotometric determinations were made as inorganic Sn using dithiol reagent. Average data obtained for apples were from 0.26 to 0.32 ppm of Sn (0.84–1.00 ppm Cy₃SnOH) and for pears from 0.12 to 0.30 ppm of Sn (040–0.99 ppm Cy₃SnOH). A residues half-life of 5–6 weeks for the apples and of 2 weeks for the pears was found.     

High-performance liquid chromatographic method for the determination of carbendazim residues in crops,grains, and wines with fluorescent detection

A normal-phase high-performance liquid chromatographic method is described for the determination of carbendazim in wine, cereals and fruits. Residues are extracted from samples with methanol. Preliminary liquid partitioning into hexane may be necessary, according to the crops, followed by liquid partitioning from aqueous solution into dichloromethane. Purification is performed by silica-column chromatography or with a silica solid-phase extraction cartridge. Determination and quantification are made by HPLC using an aminobonded stationary phase with fluorescent detection at 285/315 nm. Recoveries range from 80 to 95% for various fortification levels. The method provides a minimum detectable amount below 0.1 ng and quantification limits for various samples are between 0.01 mg kg_-1 and 0.1 mg kg_-1.     

农田尾菜发酵过程中农药残留变化特征

基于尾菜中存在农药残留的现状,以设施农业尾菜黄瓜秧为研究对象,采用气相色谱法和超高效液相色谱-串联质谱法检测了尾菜黄瓜秧在静态好氧发酵过程中多菌灵、吡虫啉、哒螨灵等50种农药残留的动态变化,并分析发酵重要影响因子堆高对农药残留消解的影响。结果表明:在尾菜黄瓜秧中共检测出腐霉利、多菌灵、嘧菌酯、苯醚甲环唑、烯酰吗啉、虫螨腈、吡虫啉、啶虫脒和哒螨灵9种农药残留,其中多菌灵平均残留量最高,达11.2 mg/kg,其他8种农药平均残留量在0.042~0.89 mg/kg之间。在发酵的24 d中,不同堆高条件下9种农药的消解规律均符合一级反应动力学方程,但不同农药半衰期差异较大,其中吡虫啉的平均半衰期最长,为28.9 d,多菌灵的平均半衰期最短,为10.2 d;不同堆高处理中农药的消解速率也有差异,总体上在2.5 m堆高下各农药的消解率最高、半衰期最短。本研究结果可为尾菜发酵参数优化、农业废弃物的高效资源化利用以及研发基于尾菜发酵产物的有机蔬菜专用有机肥提供理论支撑。     

普洱茶固态发酵过程中联苯菊酯降解规律研究

为了研究微生物在普洱茶发酵中对联苯菊酯的降解规律,以人工添加180倍液联苯菊酯的云南大叶种晒青毛茶为材料,分别设置接种黑曲霉、酿酒酵母、产黄青霉以及不接菌的对照进行普洱茶固态发酵,应用气相色谱质谱联用分析方法测定茶叶中联苯菊酯的残留,分析比较微生物在普洱茶固态发酵中对联苯菊酯农药的降解规律。结果表明,普洱茶固态发酵中联苯菊酯残留量降低,接种微生物能够有效降低联苯菊酯的含量25%左右(P0.05),其中酿酒酵母发酵对联苯菊酯农药残留的降解效果显著高于黑曲霉、产黄青霉处理(P0.05)。联苯菊酯在黑曲霉、酿酒酵母、产黄青霉以及不接菌固态发酵普洱茶过程中的降解动态规律符合一级动力学模型C=C0e~(-kt),降解曲线方程分别为:C=12.889e~(-0.043t),C=13.348e~(-0.057t),C=13.309e~(-0.042t),C=14.458e~(-0.04t)。综上,研究表明,由于优势微生物的作用,晒青毛茶上的联苯菊酯在固态发酵中显著降低,残效期缩短。     

浅析赣州蔬菜农药残留存在的问题及治理对策

近年来，赣州蔬菜生产迅速发展，栽种面积和品种不断扩大，但由于安全生产监控体系不健全，缺少有效的普及性安全用药管理，蔬菜农药残留问题仍然比较突出。赣州市农产品质量安全检测中心今年开展的七次蔬菜农药残留检测，共抽检了25种蔬菜160个样品，经检测分析，农药残留检测合     

Influence of formulation on spray deposit patterns,dislodgeable and penetrated residues,and persistence characteristics of fenitrothion in conifer needles

The influence of formulation on spray droplet spectra, deposit patterns, dislodgeable and penetrated residues, and persistence characteristics of fenitrothion in balsam fir needles was studied using three formulations containing different types of adjuvant. Spray was applied on to potted trees under controlled conditions in a laboratory chamber. Droplet size spectra and deposits were assessed using “Kromekote” cardlglass plate units. Foliar residues were measured by gas-liquid chromatography. The formulation containing polymeric adjuvants provided significantly larger droplets and higher foliar residues than those containing surfactants and co-surfactants. It also provided a higher ratio of dislodgeable-to-penetrated residues, and a slower initial rate of loss of fenitrothion. None of the formulations posed a long-term persistence problem because only very low amounts remained on foliage at 42 days post-treatment. The significance of these findings in terms of the possible increase in bioavailability of the pesticide via crawling contact is discussed.     

Determination of residues of promecarb and its metabolite, 3-methyl-5-isopropylphenol,in cattle

A procedure is described for the colorimetric determination of promecarb as 3-methyl-5-isopropylphenol in tissues using 2,6-dichlorpbenzoquinone-4-chlorimine as the chromogen. Cattle were exposed to either 1, 3, 5 or 8 spray applications of a 0·2% promecarb emulsion at 3-day intervals or were fed promecarb at 2 ppm or 20 ppm daily in the diet for 20 days. All animals were slaughtered 30 h after final exposure. Of the animals in the spraying trial, residues in omental fat ranged from 0·9 ppm to 1·5 ppm promecarb and 0·4 ppm to 1·9 ppm 3-methyl-5-isopropylphenol. Residues in perirenal fat ranged from 0·8 ppm to 1·9 ppm promecarb and 0·9 ppm to 1·6 ppm 3-methyl-5-isopropylphenol. Residues in diaphragm muscle did not exceed 0·06 ppm. In the feeding trial, the maximum residues induced were 2·2 ppm promecarb and 1·4 ppm 3-methyl-5-isopropylphenol in omental fat of an animal fed for 20 days on a diet containing 20 ppm promecarb.     

Influence of methyl bromide soil fumigation method on fungicidal efficacy and bromide residues

Highest inorganic bromine residues (30 ppm) were found when soil was fumigated with liquid methyl bromide (MB) introduced by conventional means into evaporating dishes. With preheated (vaporized) MB or injection of MB/chloropicrin (CP) mixtures, bromide concentrations were reduced by 50%. They were uniform throughout the soil (0 to 60 cm) except after MB/CP injection, when larger residues were found in the 30-60 cm layer. Leaching with 2000 m^p3/ha (20 cm) of water always reduced bromide content to 7.5 and 10 ppm at the 0-30 and 30-60 cm depth, respectively. Organic amendments to soils substantially increased bromide levels up to 118 ppm, most of which was found in the upper soil layers; two teachings with 2000 m^p3 /ha water were required to return the soils to their normal state.Sclerotium rolfsii andFusarium oxysporum f. sp.dianthi cultures buried in soil were eliminated from the upper 30 cm with MB applied either conventionally or preheated. At 50 cm, 500 kg/ha of the preheated gas was superior to 1000 kg/ha of the cold gas. All MB fumigations suppressed carnation flower yields compared with CP alone but were superior to no treatment. After leaching, MB-fumigated soils yielded the highest number of flowers.     

Persistence,distribution and dislodgeable residues of 2, 4-d following its application to turfgrass

In growth room studies, total recoverable 2, 4-D residues on or in turfgrass (Kentucky bluegrass, Poa pratensis) declined from 92% of that originally applied, to less than 66% by day 15. Although a high proportion of the applied chemical remained associated with the leaf surface under growth room conditions, only 10% was dislodged by vigorous mechanical wiping of the leaf surfaces with moistened cheese-cloth. In field studies with 1 kg acid equivalent (a.e.) ha⁻¹, less than 5% of the chemical originally applied could be dislodged with a cheese-cloth wipe at day 0. Disappearance of dislodgeable residues was very rapid. Less than 0.01% of the applied chemical was dislodgeable after 1 day in turf that received 18 mm of rainfall 1 h after spraying. Residues in turfgrass that received no rainfall required 7 days to dissipate to the same level. In a study in which the clippings were not removed, the disappearance of dislodgeable residues, when the turf was mowed at 3, 7, and 11 days after application, was nearly as rapid as in unmowed turf. In turf treated with 2.24 kg a.e. ha⁻¹ of liquid or granular formulations, dislodgeable residues were less than 1% by days 5 and 3, respectively.     

模拟加工对菠菜中农药残留量及膳食暴露评估的影响

采用田间喷药、室内模拟加工和气相色谱检测方法,研究了水洗、漂烫和烘干处理对菠菜中毒死蜱、氯氰菊酯和氰戊菊酯残留量的影响。结果表明:在田间推荐剂量下,当毒死蜱、氯氰菊酯和氰戊菊酯的有效成分用量分别为0.038 8、0.001和0.01 g/m2时,经水洗和漂烫处理,菠菜中上述3种农药的残留量分别降低22.6%、53.8%和50.8%;而加倍剂量处理时,则分别降低8.5%、61.4%和40.2%;烘干处理对毒死蜱的去除作用大于50%,但对氯氰菊酯和氰戊菊酯的去除作用仅为10%左右。对新鲜菠菜和干制菠菜的农药残留量进行膳食暴露评估的结果表明,合理的加工方式可以降低农药膳食摄入估计量的62.1%~76.7%。研究结果表明:毒死蜱的残留受水洗和漂烫影响较小,受烘干影响较大;而氯氰菊酯和氰戊菊酯的残留受水洗与漂烫影响较大,受烘干影响较小;引入加工因子后膳食暴露评估结果更接近真实值。     

Determination of residues of isofenphos and its phosphoramidate analogue

A method is described for the gas chromatographic determination of residues of isofenphos (BAY 92114, O-ethyl O-2-isopropoxycarbonylphenyl isopropylphosphor-amidothioate) and its phosphoramidate which is a potential metabolite. When potato, cabbage, rapeseed and a sandy loam soil were fortified with 0.01, 0.1 and 1.0 mg/kg and analysed by the method described, the recoveries ranged from 76 to 98%. The limits of detection of the method were 0.5 and 1.0 ng for isofenphos and isofenphos oxygen analogue respectively. Degradation under field conditions of isofenphos to its oxygen analogue was demonstrated in a sample of field-treated potatoes.     

填闲作物腐解过程及其对后茬冬小麦产量的影响

研究了渭北旱塬地区不同填闲作物（长武怀豆（S）、黑麦草（R）及两者1∶1混合（M））翻压和氮肥水平（0、60、120 kg N·hm^-2）双因素处理下,填闲作物的腐解规律、碳氮释放动态及对后茬冬小麦产量的影响,并对腐解速率与Olsen模型进行了拟合。结果表明：各填闲作物翻压后腐解规律及碳氮释放特征均表现为“前期快-中期慢-后期加快”,填闲作物腐解规律符合Olsen模型,在第276天各处理累积腐解率均达70%以上。在第0~35天,同一施氮处理下,累积腐解率和腐解速率均表现为S>M>R（P<0.05）;第35天,S、M和R各处理干物质累积腐解率分别达到61.9%、55.5%和47.5%;在0~35 d,施氮对S、M的腐解影响不显著,对R影响显著,35 d后氮肥效应逐渐减弱;填闲作物的腐解同时伴随其碳、氮的快速释放,在第21天,S、M和R碳氮残留率分别达到40%、50%和60%左右。平均来看,S的碳氮释放速率显著高于R,与M无显著差异。与裸地对照相比,翻压填闲作物能够显著提高后茬冬小麦产量,其籽粒产量增加10%~35% （P<0.05）,其中翻压长武怀豆低氮处理和混合翻压低氮处理效果最佳。     

The behaviour of residues of benzoylprop-ethyl and its breakdown products in wheat

Samples of wheat grain and straw have been analysed from trials with the wild oat herbicide benzoylprop-ethyl ( I ) in several countries. Following recommended commercial treatments (application of 1.0–1.6 kg ha^?1 at Feekes growth stage G-J), total residues of I and its hydrolysis product N-benzoyl-N-(3,4-dichlorophenyl)-DL - alanine (free and conjugated) were low and in the majority of instances they were < 0.01 mg kg^?1 in samples of grain from the UK, although rather higher residues were detected in some grain samples from other countries. Residues in straw were higher, but normally did not exceed 2 mg kg^?1, and were rather variable, possibly as a result of differences in agricultural practice.     

The behaviour of residues of flamprop-isopropyl and its breakdown products in barley

Residue data are reported for flamprop-isopropyl ( I ) in barley grain and straw samples following applications of the herbicide to crops grown in eight countries. The samples were analysed for I and its hydrolysis product N-benzoyl-N-(3-chloro-4-fluorophenyl)-DL -alanine ( II ). Following recommended applications (normally 1 kg ha^?1 at Feekes scale G-I/J), residues of I and II in the grain were low (90% were <0.02 mg kg^?1 for I , 86% were <0.06 mg kg^?1 for II , levels which were essentially the limits of determination). Residues in straw were higher and more variable, but again 63 and 77% of samples were below 1 mg kg^?1 for I and II , respectively.     

Influence of soil pH-sorption interactions on the carry-over of fresh and aged soil residues of imazamox

Long-term carry-over of some imidazolinone herbicides has been observed in soil that is below pH 6.5, resulting in significant damage to sugarbeet. In a field study in south-west Minnesota, imazamox concentration decreased rapidly in soil, regardless of pH. Despite similar amounts of aged soil residues of imazamox remaining at different pH levels, bioavailability differed with pH as a result of pH effects on sorption–desorption interactions. At low pH, more imazamox was sorbed than at high pH, but it was readily desorbed. At high pH, less imazamox was sorbed initially, but it did not readily desorb. Thus, after 3 months, the remaining imazamox in low-pH soil was desorbable and bioavailable, resulting in injury to oilseed rape and sugarbeet. In aged, low-pH soil, adding lime released bound imazamox, which was then degraded, resulting in less carry-over.     

Pesticide residues in foodstuffs in Great Britain: Organochlorine residues in imported cereals,nuts, pulses and animal foodstuffs

Results are presented for the determination of organochlorine insecticide residues in imported cereals, nuts, pulses and animal foodstuffs for the 2 year period July 1969 to June 1971. BHC was found in all but four of the 248 samples examined but only in 25 (10%) did the level exceed 0.5 mg/kg. DDT was found in 39% of the samples of which three samples of wheat contained more than 1 mg/kg and two samples of cottonseed cake more than 0.5 mg/kg. The other commodities sampled had less than 0.2 mg/kg. DDE was detected in trace amounts in 26 % of the samples examined.     

QuEChERS-高效液相色谱-串联质谱法检测荔枝中氯虫苯甲酰胺、溴氰虫酰胺及代谢物残留

采用高效液相色谱-串联质谱(HPLC-MS/MS)技术,结合改良的QuEChERS法,建立了同时测定荔枝中氯虫苯甲酰胺、溴氰虫酰胺及代谢物J9Z38残留的分析方法.样品用乙腈提取,以N-丙基乙二胺(PSA)和十八烷基键合硅胶(C18)组合吸附剂净化,采用C18反相色谱柱分离,以V(甲酸水溶液):V(乙腈)=15:85为...     

On-column esterification and N-methylation of carbetamide with N,N,N-trimethylanilinium hydroxide

Transesterification and N-methylation of carbetamide was carried out using N,N,N-trimethylanilinium hydroxide as an alkylation reagent. The final product of the on-column methylation appeared as the dimethyl derivative of carbetamide which was qualitatively identified and quantitatively determined by means of gas-liquid chromatography. The standard methyl N-methylcarbanilate was analytically identified by a mass spectrometric method.     

丁香假单胞菌发酵液中的冠菌素含量测定方法及其应用

为了辅助提高工程菌种改良的效率,建立了一种简单、快速、高效的分散液-液微萃取-高效液相色谱检测丁香假单胞菌发酵液中冠菌素的分析方法。优化了蛋白沉淀法、萃取剂的种类和体积、分散剂的种类和体积、萃取时间和离心强度等对萃取率的影响。确定最优萃取条件为:以2.0 mL丙酮作为分散剂,以400 μL氯苯为萃取剂,萃取5 min,在5 000 r/min下离心5 min。高效液相色谱的检测条件为:流动相为V (甲醇) : V (0.5%乙酸水溶液) = 70 : 30,等梯度洗脱,流速1.0 mL/min,柱温30 ℃,检测波长220 nm。在3.2~100 mg/L范围内,冠菌素的峰面积与其质量浓度间呈良好的线性关系,相关系数 (r) 为0.999 8。方法的检出限为2.1 mg/L,定量限为6.5 mg/L。在6.5、25和100 mg/L添加水平下,冠菌素在丁香假单胞菌发酵液中的回收率在95%~98%之间,相对标准偏差 (n = 5) 在2.7%~5.1%之间。该方法可用于丁香假单胞菌发酵液中冠菌素含量的测定。