悬浮液进样-石墨炉原子吸收光谱法测定巴戟天中痕量铅和镉

GF-AAS Determination of Trace Amounts of Lead and Cadmium in Morinda Officinalis with Direct Suspension Sample Introduction

取经烘干粉碎并通过0.074mm网筛的巴戟天样品0.050 0g,加入琼脂溶液10.0mL(其中含磷酸二氢铵0.1g,作为基体改进剂),超声振荡5min,制成样品的悬浮液,直接进样,采用石墨炉原子吸收光谱法测定其中铅和镉的含量。设置铅和镉的灰化温度分别为850℃和800℃。结果表明:铅和镉的质量浓度在一定范围内与其吸光度呈线性关系,铅和镉的检出限(3s×V/b)分别为2.17×10-9 mg和3.4×10-10 mg。按照标准加入法进行加标回收试验,铅和镉的回收率分别在98.8%～103%和98.3%～104%之间。精密度试验表明铅和镉的测定值的相对标准偏差(n=7)分别为2.7%和1.2%。

0.0500 g of the dried and powdered morinda officinalis sample(passed through 0.074 mm sample sieve)was taken and dispended in 10.0 mL of agar solution(containing 0.1 g of NH4 H2 PO4 as matrix modifier)with an ultrasonotor for 5 min,to make a suspension of the sample which was introduced into the instrument for GF-AAS determination of lead and cadmium.Ashing temperatures for lead and cadmium were set at 850 ℃ and800℃,respectively.As shown by the results,linear relationships between values of absorbance and mass concentration of lead and cadmium were found in definite ranges,with detection limits(3 s×V/b)of 2.17×10^-9 mg and 3.4×10^-10 mg respectively.Test for recovery was made by standard addition method,giving results in the range of 98.8%-103% and 98.3%-104%,respectively.Values of RSDs(n=7)were found 2.7%(for Pb)and 1.2%(for Cd).