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目的研究EDTA滴定法测定水体暂时硬度的检测方法。方法配制一系列待测溶液,研究碳酸氢钙在加热条件下完全分解产生碳酸盐沉淀所需要的最适时间,分析该方法的检出限,并用加标回收方法分析方法的回收率和精密度。结果加热30 min时,不同浓度下碳酸盐均可完全沉淀。方法的最低检出限为14 mg/L,小于等于此浓度时,实验误差较大。该方法的加标回收率在95.92%～179.14%之间,其中浓度为14.66 mg/L时由于误差较大,所以加标回收率偏差最大为179.14%。当样品浓度高于50 mg/L时,方法相对标准偏差(RSD%)为4.2%～4.4%。结论该检测方法操作和计算简便,精密度较高。
Objective To study the method of EDTA titrimetric determination of temporary hardness of water bodies. Methods A series of test solutions were prepared to study the optimum time required for the decomposition of calcium bicarbonate to produce carbonate precipitation under heating. The detection limits of the method were analyzed. The recoveries and precision of the method were analyzed by spike recovery method degree. Results When heated for 30 min, carbonate was completely precipitated at different concentrations. The minimum detection limit of the method is 14 mg / L. When the concentration is less than or equal to this concentration, the experimental error is large. The spiked recoveries of this method ranged from 95.92% to 179.14%, with the maximum error of spike recovery of 179.14% due to the large error of 14.66 mg / L. The method relative standard deviation (RSD%) was 4.2% -4.4% at sample concentrations above 50 mg / L. Conclusion The method is easy to operate and calculate, with high precision.