异菌脲在梨和土壤中残留量的测定方法

建立了异菌脲在梨和土壤中气相色谱分析方法。梨、土壤样品用乙腈提取,Florisil固相萃取小柱净化,淋出液浓缩后用正己烷定容,气相色谱仪电子捕获器检测。试验结果表明,异菌脲的含量与峰面积之间呈线性关系,异菌脲的最小检出量为0.005ng。对于梨样本,异菌脲最低检测量为0.01mg/kg,添加平均回收率为94%～107%,变异系数为3.2%～6.5%;对于土壤样本,异菌脲最低检测量为0.01mg/kg,添加平均回收率为98%～110%,变异系数为4.0%～10.5%。结果表明该残留分析方法的灵敏度、准确度、精密度等均符合农药残留检测的要求。     

异菌脲在不同栽培模式下的降解动态

采用气相色谱法研究了异菌脲在大棚和露地青菜上的残留降解动态.喷施500 g/L的异菌脲悬浮剂1000倍后,异菌脲在露地青菜上原始沉积量为41.04 mg/kg,药后14 d残留量为1.34 mg/kg,消解率达到96.7%,半衰期为1.98 d,在大棚青菜上的原始沉积量为33.15 mg/kg,药后14 d残留量为1.53 mg/kg,消解率达到95.4%,半衰期为2.45 d,两者无明显差异.异菌脲在露地青菜和大棚青菜上的残留量均符合一级反应动力学方程.以5 mg/kg为其最高残留限量,推荐其在青菜上的安全间隔期为8 d.     

Feasibility of LC/TOFMS and elemental database searching as a spectral library for pesticides in food

Traditionally, the screening of unknown pesticides in food has been accomplished by GC/MS methods using conventional library-searching routines. However, many of the new polar and thermally labile pesticides are more readily and easily analysed by LC/MS methods and no searchable libraries currently exist (with the exception of some user libraries, which are limited). Therefore, there is a need for LC/MS libraries that can detect pesticides and their degradation products. This paper reports an identification scheme using a combination of LC/MS time-of-flight (accurate mass) and an Access database of 350 pesticides that are amenable to positive ion electrospray. The approach differs from conventional library searching of fragment ions. The concept consists of three parts: (1) initial screening of possible pesticides in actual market-place fruit extracts (apple and orange) using accurate mass and generating an accurate mass via an automatic ion-extraction routine, (2) searching the Access database manually for screening identification of a pesticide, and (3) identification of the suspected compound by accurate mass of at least one fragment ion and comparison of retention time with an actual standard. Imazalil and iprodione were identified in apples and thiabendazole in oranges using this database approach.     

高效液相色谱法测定蔬菜中异菌脲残留量的不确定度分析

采用高效液相色谱法对蔬菜中异菌脲残留量的不确定度进行评估。根据JJF 1135—2005《化学分析测量不确定度评定》和JJF 1059.1—2012《测量不确定度评定与表示》中的有关规定,建立测定蔬菜中异菌脲残留量不确定度的数学模型,逐层对不确定度来源进行分析。通过对不确定度分量进行量化和合成,得出当蔬菜中异菌脲残留量为5.31 mg/kg时,其扩展不确定度为0.40 mg/kg(k=2)。结果表明,影响检测结果的主要因素为标准溶液配制、标准曲线拟合和测量重复性等。     

500g/L异菌脲水悬浮剂的研制

介绍了水悬浮剂剂型的优点以及异菌脲的防治对象，重点研究了异菌脲水悬浮剂的制备方法以及技术原理．并分析了影响该悬浮剂稳定性、粒径的因素．最后确定了最佳配方组方及技术指标。     

40%异菌·氟啶胺悬浮剂高效液相色谱分析

采用高效液相色谱法分析氟啶胺与异菌脲复配制剂,使用ZORBAX SB C18反相柱和紫外可变波长检测器,以乙腈+冰乙酸水溶液为流动相,外标法对有效成分进行分析和定量。氟啶胺和异菌脲标准偏差分别为0.07和0.08,变异系数分别为0.34%和0.38%,平均回收率分别为99.4%和99.6%。方法具有简便、快速,精密度和准确度高的特点。     

Multi-residue analysis of captan,captafol, folpet,and iprodione in cereals using liquid chromatography with tandem mass spectrometry

ABSTRACT

In this study, we propose an improved analytical method for the multiresidue analysis of captan (plus its metabolite, tetrahydrophthalimide), folpet (plus its metabolite, phthalimide), captafol, and iprodione in cereals using liquid chromatography tandem mass spectrometry (LC-MS/MS). As captan, captafol, and folpet are easily degraded during homogenisation and extraction, samples were comminuted with liquid nitrogen, and both QuEChERS and ethyl acetate-based extraction workflows provided a satisfactory method performance. The optimised LC-MS/MS procedure with electrospray ionisation did not degrade these compounds, and offered sufficient method selectivity by resolving and minimising co-eluting matrix-derived interferences. The method also resolved the problem of non-specific mass spectra that these compounds usually produce on GC-MS analysis involving electron ionisation. The method performance was satisfactory for all 6 compounds at 0.01 mg kg^?1 and higher levels of fortification, and validated as per the SANTE/11813/2017 guidelines of analytical quality control in a wide range of cereals including rice, wheat, sorghum, and corn. The method provides special advantage of simultaneous analysis of captan, and folpet along with their metabolites (tetrahydrophthalimide, and phthalimide, respectively) in combination with captafol, and iprodione in a single chromatographic run. Although iprodione is known to degrade to 3,5-dichloroaniline, since this metabolite is not a part of the residue definition, it was not included in the scope of this method. As the method demonstrates satisfactory selectivity, sensitivity, accuracy, precision, and robustness in a wide range of cereal matrices, it is recommended for regulatory testing of these compounds in cereals.     

异菌脲在油菜籽中残留分析方法研究

建立异菌脲在油菜籽中的残留分析方法.样品以丙酮提取,两次液液分配后,活性炭处理,高效液相色谱检测.异菌脲的最小检测量为0.0666ng,用优化后的方法在油菜籽中分别进行添加回收实验,得到的平均添加回收率为79.15%～119.65%,变异系数为2.34%～7.36%.该方法的准确性、灵敏度均达到农药残留分析的要求.     

40%烯酰·异菌脲悬浮剂液相色谱定量分析

建立了在同一色谱条件下测定混剂中烯酰吗啉和异菌脲含量的方法。采用250 mm×4.60 mm（i.d.）InertsilODS-3 C₁₈柱分离,以甲醇-乙腈-水（醋酸调pH≈3.0）（体积比为35:35:30）为流动相,在220 nm紫外检测波长下,经保留时间定性确证,峰面积外标法进行定量分析。结果为:烯酰吗啉与异菌脲的线性相关系数分别为0.999 7和0.999 8;变异系数分别为0.34%和0.39%;平均回收率分别为99.68%和99.21%。     

不同清洗方式对百菌清等3种杀菌剂残留的去除效果

研究清水冲洗和不同浸泡时间对茄子上百菌清、三唑酮、异菌脲残留的去除效果。百菌清由于非内吸性、水溶性差,以清水冲洗效果最好;三唑酮由于内吸性、水溶性好,浸泡时间越长越有利于农药的去除;异菌脲虽然为非内吸性、水溶性差,但是其制剂为悬浮剂,利于在茄子表面吸附,因而去除效果相对较差。比较3种杀菌剂在茄子上的去除效果,为三唑酮>百菌清>异菌脲。