水中铁检测的质量控制

Quality Control of the Determination of Iron in Water

目的确保水中铁测定数据的可靠性和准确性。方法用二氮杂菲分光光度法及原子吸收分光光度法测定井水、河水、溪水、自来水共177份水样中铁含量,探讨了水样的混匀以及保存条件对测定结果的影响,并分析了水样铁含量超标的原因。结果未混匀水样与混匀水样铁含量超标率分别为5.08%和31.64%,χ2=39.87,P<0.01,差异有非常显著性。水样浊度≤3度时,水样混匀与否对测定结果影响差异无显著性;水样浊度≥4度时,混匀水样铁含量显著高于未混匀水样(P<0.01),差异有非常显著性。劣质输水管和打井用具等可污染水源,造成铁超标。原水不加酸保存与加酸保存15d内测定结果差异无显著性。结论水中铁含量测定影响因素较多,现场采样和实验取样需混匀,对超标样品应跟踪分析,才能保证数据的可靠性和准确性。

Objective To ensure the reliability and accuracy of the data of the determination of iron in water. Methods The contents of iron in 177 water samples including well water, river water, steam water and tap water were determined by 1,10-phenanthroline spectrophotometry and atomic spectrophotometry.The effects of homogenous state and storage condition of water samples on the results of assay were analyzed ,the reason for the excessive iron in water samples was analyzed also. Results The rates of exceeding the standard were 5.08% for water samples untreated by well mixing during sampling and 31.64% for those treated by well mixing,there was significant difference between them(χ2=39.87,P<0.01). There was no significant difference in the contents of iron between the water samples with the tuibidity of ≤3 degrees treateed by well mixing and not.The water samples with the tuibidity of ≥4 degrees treated by well mixing showed significantly higher contents of iron compared with those untreated by well mixing(P<0.01).The application of water supply pipes with inferior quality and drilling tools might contaminate water source and resulted in excessive iorn in the water samples . There was no significant difference in the contents of iron between the raw water samples stored under conditions with and without acidulation within the 15 day-reserved period. Conclusion The results of determination of iron in water samples were effected by many factors. Completely mixing after water sampling in situ and in laboratory and follow up investigation on water samples with excessive iron were essential to ensure the reliability and accuracy of the data of the determination of iron in water.