在线预还原-氢化物发生-原子荧光光谱法测定尿液中总无机砷

HG-AFS Determination of Total Inorganic Arsenic in Urine with On-line Pre-reduction

自行设计并制作了一种在线自动还原装置用于将尿样中可能存在的无机砷从砷(Ⅴ)还原砷(Ⅲ)。为使砷(Ⅴ)还原至砷(Ⅲ),将尿样4.8mL与1.2mL混合还原剂(每升溶液中含硫脲100g及抗坏血酸50g)混合后在反应器中于70℃加热2min。分取此溶液1.5mL与20g.L-1硼氢化钾溶液(溶于5g.L-1氢氧化钠溶液中)2.0mL,在氢化物发生器中反应生成AsH3,然后由载气(氩气)带至原子化器中,并进行原子荧光检测,所制的在线还原器及测定砷的方法已应用于儿童尿样中无机砷的测定,并在这些样品的基础上用标准加入法做回收试验,测得回收率在90.2%～102.6%之间。

A self-made on-line automatic reductor was designed and fabricated,for pre-reduction of inorganic arsenic（Ⅴ） to As（Ⅲ）,which may possibly present in the urine sample.The pre-reduction was performed by mixing 4.8 mL of urine sample with 1.2 mL of the reductant（mixed solution of 100 g·L-1 thiourea-50 g ·L-1 ascorbic acid） and heated in a reactor at 70 ℃ for 2 min.An aliquot of the reduced As（Ⅲ） solution（1.5 mL） was reacted with 2.0 mL of 20 g·L-1 KBH4（dissolved in 5 g·L-1 KOH solution） in the hydride generator,and the AsH3 formed was carried over to the atomizer by the carrier gas（Ar）,and the AFS measurement was made.The proposed method has been applied to the analysis of children′s urine samples,and test for recovery was made on the base of these samples by standard addition method,giving values of recovery in the range of 90.2%-102.6%.