微珠比色法用于野外现场天然水样和化探样品中微量铁的分析

In-situ Analysis of Trace Iron in Natural Water and Chemical Exploration Samples by Micro-bead Colorimetry

针对野外现场分析的要求,选择微珠比色技术用于江河天然水样和化探样品中铁的分析。以向红菲啰啉为显色剂,硫代硫酸钠掩蔽铜的干扰,方法摩尔吸光系数为1×105L.mol-1.cm-1,精密度(RSD,n=10)为2.5%,适用于0.001μg/g以上的铁的测定。方法用于江河天然水样和化探样品中铁的测定,结果与分光光度法相符。方法在拟定的过程中注意了降低环境污染、降低成本和提高方法的可操作性。建立的方法干扰少,选择性好,对实验环境条件要求不高,满足野外现场分析应用。对于天然水可直接测定;但一般的化探样品由于铁含量较高,需要稀释后再测定。

A method for the field in-situ determination of trace iron in natural water and chemical exploration samples by micro-bead colorimetry was developed. Based on the chromagenic reaction of iron with 4,7-phenyl-1 ,lO-phenanthroline （apparent molar absorptivity is 1 × 10^5 L· mol^-1· cm^-1） and Na2S203 as a masking reagent for eliminating the interference from Cu, the method provides detection limit of 0. 001 μg/g for Fe. The method has been applied to the determination of trace iron in natural water and chemical exploration samples and the results are in agreement with those from spectrophotometry with precision of 2.5% RSD （ n = 10）. But in the analysis of samples with higher content of Fe, the sample solution should be further diluted. The method also provides the advantages of higher sensitivity, accuracy and precision, low cost and less environmental pollution.