聚合氯化铝中六价铬的石墨炉原子吸收光谱测定法

Determination of hexavalent chromium in polyaluminium chloride by graphite furnace atomic absorption spectrometry

目的建立聚合氯化铝中六价铬含量测定的石墨炉原子吸收光谱法。方法以氢氧化钠沉淀聚合氯化铝样品中大量的铝离子以及部分杂质离子,沸水浴加热使六价铬充分游离,用磷酸调pH中性后趁热抽滤以减少沉淀对六价铬的吸附。选择波长357.9 nm,狭缝0.2 nm,灯电流7.0 mA,以1%抗坏血酸为基体改进剂,用石墨炉原子吸收光谱法进行测定。结果在0.010~0.050 mg/L线性范围内,该方法所得六价铬的回归方程为y=0.015 76x+0.032 44,r=0.999 5。该方法的检出限为0.8μg/L,平均加标回收率为92.0%~96.7%,RSD为2.98%~3.90%。结论该方法所用试剂简单,操作容易,解决了测定聚合氯化铝中六价铬存在的加标回收率不理想的问题。

Objective To establish a graphite furnace atomic absorption spectrometry meheod for the determination of hexavalent chromium in polyaluminium chloride(PAC).Methods Various aluminum ions and some impurity ions in the sample were precipitated with sodium hydroxide.Hexavalent chromium was fully dissociated by boiling bath heating and pH was adjusted to neutral by phosphoric acid.The sample was treated hot filtration to reduce precipitation adsorption of hexavalent chromium.At the conditions,such as 357.9 nm wavelength,0.2 nm slit,7.0 mA lamp current,and 1%ascorbic acid as the matrix modifier,graphite furnace atomic absorption spectrometry was employed to carry out the determination.Results The linear ranges of hexavalent chromium was 0.010-0.050 mg/L.The linear equation was y=0.015 76 x+0.032 44(r=0.999 5).The limit of detection was 0.8μg/L and the average recovery rates ranged from 92.0%to 96.7%.RSDs were 2.98%-3.90%.Conclusion The method established in the present paper is easy to operate and the chemical reagents used in this method is simple,with satisfactory recovery rate.