氨基酸-乙酰丙酮分光光度法测定水样中甲醛

Spectrophotometric Determination of Formaldehyde in Water Sample with Amino Acid-Acetylacetone

试验了用氨基酸代替氨水或乙酸铵作为胺源的条件下,乙酰丙酮与甲醛反应生成有色化合物的适宜条件并提出了氨基酸-乙酰丙酮分光光度法测定水中甲醛的方法.优化的试验条件如下:①0.12mol·L-1甘氨酸衍生剂用量为2 mL;②反应温度为50℃;③反应时间为15 min;④反应体系的pH为4.7.甲醛的质量浓度在0.2～1.0mg·L-范围内与吸光度呈线性关系,检出限为5 μg·L-1.加标回收率均不小于98.0％,测定值的相对标准偏差(n=6)均不大于4％.方法应用于地表水样中甲醛的测定,测定值与国标法测定结果相符.

Conditions for the color reaction of formaldehyde with acetylacetone by using amino acids instead of aq.ammonia or ammonium acetate as the donor of-NH2 group were tested and a spectrophotometric method for determination of formaldehyde in water sample with glycine and acetylacetone as reagents was proposed.The optimized conditions found were as follows:① amount of 0.12 mol · L-1 glycine derivatizing agent:2 mL; ②temperature of reaction:50 ℃ ; ③ time of reaction:15 min; ④ pH of reaction system:4.7.Linear relationship between values of absorbance and mass concentration of forraldehyde was obtained in the range of 0.2-1.0 mg ·L-1,with detection limit of 5μg · L-1.Values of recovery found by standard addition method were over 98.0％,and values of RSD's (n=6) less than 4％.The proposed method was used in the analysis of sample of surface water,giving results of formaldehyde contents in consistency with values found by GB method.