水样浊度对甲醛含量测定结果的影响及减小影响的措施初探

Study on the Effect of the Turbidity of Water Sample to Formaldehyde Content and Corresponding Deduction Way

用乙酰丙酮法测定地表水中的甲醛含量时,即使干净的水样,也存在一定的浊度,而浊度可在一定程度上通过750 nm处的吸光度(A750)反映出来;预实验发现纯水配置的空白和标准溶液的A750与实际水样间有显著差异;进一步实验发现,在实际水样的测定中,用414 nm处的吸光度(A414)和A414-A750计算得到的结果间也存在显著差异,可见水样浊度对计算结果有显著影响;建议测定方法中A414去除浊度影响后再参加运算。

The method with acetylacetone was used to measure the content of formaldehyde in surface water samples. To some extent, the absorbances at 750 nm（A750） by water sample could indicate the turbidity which was unavoidable in water sample. During pre-experiment, significant difference was found between water samples and pure water while the content of formaldehyde in water samples was measured by the method with acetylacetone. The same significant difference were found between the content of formaldehyde calculated with the absorbances at 414 nm （A414） and Aala-A750 in water samples. The results showed that the turbidity of samples may interfere with the calculation of formaldehyde concentration. Therefore, the turbidity of samples should be deducted from A414 before calculating the concentration.