分散式固相萃取结合高效液相色谱法测定植物油中苯并(a)芘含量的不确定度分析

Uncertainty analysis on determination of benzo(a)pyreneresidues in plant oil by high performance liquid chromatography with dispersive solid phase extraction

目的建立适用于分散式固相萃取结合高效液相色谱法测定植物油中苯并(a)芘含量的不确定度分析方法。方法样品用正己烷稀释后,加入适量吸附剂和去离子水,经分散式固相萃取净化,浓缩定容后应用Eclipse XDB-C18色谱柱(4.6 mm×150 mm,5μm)对苯并(a)芘含量进行分析,流动相以乙腈-水(v:v=88:12)进行等度洗脱,采用荧光检测器(激发波长Ex=384 nm,发射波长Em=406 nm)检测,外标法定量。依据JJF 1135-2005《化学分析测量不确定度评定》中相关规定,考查称量、定容体积、标准曲线、仪器测量重复性和回收率等引入不确定度的主要因素,并对不确定度的各分量进行计算和合成。结果当植物油中苯并(a)芘含量为4.33μg/kg时,在95%的置信区间下,其扩展不确定度为0.66μg/kg(k=2)。评定结果表明,标准曲线拟合和标准溶液的配置产生的不确定度对合成不确定度的影响较大,而样品称量所引入的不确定度较小可忽略不计。结论该评定方法客观准确,适用于分散式固相萃取结合高效液相色谱法测定植物油中苯并(a)芘含量的不确定度分析,对检测结果准确度的提高具有参考意义。

ABSTRACT:Objective To establish a method for the determination and uncertainty analysis of benzo(a)pyrene residues in plant oil by dispersive solid phase extraction coupled with high performance liquid chromatography(HPLC).MethodsThe sample diluted with hexane was cleaned by dispersed solid phase extraction. Then the concentrate of constant volume was analyzed by liquid chromatographic column named Eclipse XDB-C18 (150 mm×4.6 mm, 5μm), using acetonitrile:water (88:12,v:v)as mobile phase. In addition, coupled with fluorescence detector (FLD) (Ex=384 nm,Em=406 nm), the target was quantified with external standard curve. According to JJF 1135-2005, the factors affecting the determination results were investigated, such as weighing, constant volume, standard curve, measurement repeatability and recovery rate. Meanwhile, each component of uncertainty was calculated and combined.ResultsWhen the determination result of benzo(a)pyrene residues in plant oil was 4.33μg/kg, under the confidence interval of 95%, the expanded uncertainty was 0.66μg/kg (k=2). The results showed that the primary influences on the combined standard uncertainty were the standard curve and the configuration processof standard solution, and the weighing factor was very small toneglected.ConclusionThe evaluation method is suitable for objective and accurate analysis of uncertainty of benzo(a)pyrene residues in plant oil by dispersive solid phase extraction coupled with HPLC. This method provides the reference for the accuracy of detectionresult.