豇豆中啶虫脒基体标准物质的研制

目的：建立豇豆中啶虫脒基体标准物质的研制方法。方法：将新鲜种植的空白豇豆样品粉碎、冻干、添加、混匀、二次冻干、粉碎、过筛、混匀、包装、Co60辐照灭菌。采用液相色谱—质谱串联方法进行检测，基体标准溶液定量校正。通过均匀性、稳定性检测合格后，采用实验室联合定值的方式进行测量定值。结果：该方法制备的样品易于贮藏、运输和稳定保存，均匀性、稳定性良好，其啶虫脒特性值为(0.283 7±0.008 5) mg/kg(k=2)。结论：试验制备的豇豆中啶虫脒基体标准物质符合国家计量技术规范中均匀性、稳定性要求，准确度良好，能够应用于检测过程中质量控制、分析仪器校准、检测方法确认评估等工作。

Preparation of matrix reference material for acetamiprid in cowpeas

Objective:To establish a method for the preparation of acetamiprid matrix reference material in cowpeas.Methods:Planted fresh blank cowpea which meets the requirements of reference material development was selected as the research object to obtain dry powder after crushed, freeze-dried, added, mixed, twice freeze-dried, crushed, screened, mixed, packaged and Co60 irradiation sterilized. The dry powder sample was determined by Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) and calibrated for quantitative determination by matrix standard solution. After homogeneity and stability studies, coordinated value was determined by 9 laboratories and the uncertainty was evaluated.Results:The prepared sample of cowpea freeze-dried powder had good homogeneity and stability, for which it was convenient to storage transport and preserve in stable status during the testing time. The property value and expanded uncertainty of acetamiprid was (0.283 7±0.008 5) mg/kg (k=2), certified by 9 independent laboratories.Conclusion:The matrix reference material prepared by this method has good homogeneity, stability and accuracy in request of the national metrology technical specification, which can be used in the quality control in process of testing, calibration of analytical instruments and development and verification of testing method, etc.