气相色谱法检测大米中溴氰菊酯残留量的测量不确定度评价

目的通过对气相色谱法检测大米中溴氰菊酯残留量的测量不确定度来源的系统分析，提高对大米中溴氰菊酯残留量的检测水平和能力，并找出影响测量结果不确定度的主要因素。方法按照JJF1059．1—2012（GUM）《测量不确定度评定和表示》和《CNAS—CL05：2011》的要求，找出分析不确定度的来源，建立测量模型，计算各不确定度分量，对其进行评定。结果大米中溴氰菊酯农药残留量的测量不确定度由标准曲线拟合、样品前处理后的回收率、标准溶液的逐级稀释、样品结果的重复性、样品称量、标准物质等引入的不确定度各组分合成。测量结果的扩展不确定度按公式U：k×u（合）计算。测定结果报告C=CX±U，以加入溴氰菊酯的标准物质的0．30mg／kg的大米做气相色谱法检测残留量，报告为（0．30±0．0622）mg／kg。结论从气相色谱法检测大米中溴氰菊酯残留量的测量不确定度分量汇总分析可以看出，影响不确定度的因素有很多，而样品的前处理及标准曲线拟合是最为关键的因素。

Evaluation on measurement uncertainly of detection of deltamethrin residues in rice by gas chromatography

[ Objective ] To analyze the source of measurement uncertainty of detection of dehamethrin residues in rice by gas chromatography, improve the level and ability of measuring deltamethrin residues in rice and find out the primary factors of affecting measurement uncertainty. [ Methods] According to JJF 1059.1-2012 （GUM） ＂Measurement uncertainty evaluation and presentation＂ and CNAS-CL05： 2011, the source of measurement uncertainty was found, the measurement model was established, the measurement uncertainty was calculated and evaluated. [ Results ] The measurement uncertainty of deltamethrin residues in rice was made up of the measurement uncertainty of standard curve fitting, the recovery of sample preparation, the cascade dilution of standard solution, sample of repeatability, sample weighing, reference materials. The expanded measurement uncertainty was calculated by U = k × u. The expression of measurement results were C = CX±U. Deltamethrin residues were （0. 30± 0. 062 2 ） mg/kg in rice which the standard substance of dehamethrin was added to 0.30 mg/kg detected by gas chromatography. [ Conclusion] From the analysis of measurement uncertainty of detection of deltamethrin residues in rice by gas chromatography, we can see that there are many factors affecting the measurement uncertainty, pretreatment of samples and standard curve fitting are the most critical factors.