微量甲醛标准溶液的配制与标定分析——以碘量法为例

Analysis on preparation of trace formaldehyde standard solution and its calibration by iodimetry

测定样液中微量甲醛的含量时,需事先配制和标定含微量甲醛的标准溶液。碘量法是标定甲醛溶液的常用方法。为获得具有较好精确度的微量甲醛标准溶液,根据滴定分析原理进行计算后认为,配制质量浓度为1000 mg/L的标准甲醛储备液既适宜标定,也便于稀释应用。在标定中所用的硫代硫酸钠溶液和碘液配制成合适的浓度有利于提高标定甲醛储备液的精确度。

In order to determine the content of trace formaldehyde in a sample solution,it is necessary to prepare and calibrate a standard solution containing trace formaldehyde in advance.Iodimetry is a common method to calibrate formaldehyde solution.For preparing the standard solution of trace formaldehyde with better accuracy,it was concluded after some calculation based on the principle of titrimetry that the mass concentration of formaldehyde standard solution should be preferably 1000 mg/L,which is suitable for both calibration and dilution.The preparation of a sodium thiosulfate solution and an iodine solution both with an appropriate concentration is helpful to improve the accuracy of calibration of formaldehyde stock solution.