硝酸介质-氢化物原子荧光光谱法测定食品中的铅

Determination of lead in food by nitric acid medium-atomic fluorescence spectrometry

目的建立一种操作简便、试剂用量少、样品介质干扰少、检出限低、准确度高的原子荧光光谱法检测食品中铅的测定方法。方法样品采用湿法消解,经驱赶残酸处理后,用1.5%硝酸介质溶解并加入草酸作为干扰抑制剂,以KBH4-K3Fe(CN)6-KOH混合液作为载入剂体系,其中KBH4和K3Fe(CN)6浓度为20 g/L,KOH浓度为1.4 g/L,用氢化物原子荧光光谱法测定食品中的痕量铅。结果该法在5.0μg/L^50.0μg/L,回归方程为y=40.0x+167.2,具有良好的线性关系(r=0.9998),检出限为0.08μg/L。取样量为2 ml时,最低检出浓度为0.001 mg/ml;取样量为0.5 g时,最低检出浓度为0.004 mg/kg。在加标水平为5.0μg/L、10.0μg/L、20.0μg/L和40.0μg/L时,5种食品的回收率为90%~101%。结论该法取样量少、预处理简单、分析速度快、准确度高,可作为实验室开展食品痕量铅检测的优选方法。

Objective To establish an atomic fluorescence spectrometry（ AFS） method with simple operation,less reagent,low interference in sample matrix,low detection limit and high accuracy for quantitation of lead in food. Methods Samples were digested with heated acid,the residue acid was removed,and then samples were mixed with 1. 5% nitric acid to dissolve the residue. Added oxalic acid as the interference inhibitor,and KBH4- K3Fe（ CN）6- KOH mixed solution was used as the loading agent system,in which the concentration of KBH4 and K3Fe（ CN）6was 2 g / L,and the concentration of KOH was 1. 4 g / L,then,the concentration of trace lead in food was detected by hydride generation atomic fluorescence spectrometry.Results This method exhibited a linear relation was 5. 0 μg / L ~ 50. 0 μg / L. The regression equation was y = 40. 0x ＋ 167. 2（ r = 0. 9998） and the minimum detectable limit of this method was 0. 08 μg/L. The minimum detectable concentration was0. 001 mg / ml with 2 ml samples as well as 0. 004 mg / kg with 0. 5 g samples. Furthermore,the recoveries of lead in five kinds of food were 90% ~ 101% while the contents of added standard were 5. 0 μg / L,10. 0 μg / L,20. 0 μg / L and 40. 0 μg / L.Conclusion This simple,rapid,accurate and reliable analytical method is an optimum method for the determination of lead in food in an ordinary laboratory conditions.