在氢氧化钾溶液介质中，甲醛与4-氨基-3-联氨-5-巯基-1,2,4-三氮杂茂（简称AHMT）起缩合反应，高碘酸钾将缩合反应产物氧化成6-巯基-5-三氮杂茂﹝4,3-b﹞-S-四氮杂苯紫红色化合物，据此建立了分光光度法测定乙二醛中微量甲醛的新方法。最大吸收波长为554nm，吸光度变化值与甲醛浓度在0~1.4μg·mL-1范围内呈良好的线性关系，相关系数为0.9956，相对标准偏差为2.57%（n=6），加标回收率在95.8%~108.7%之间。%A new determination method was builded for the trace formaldehyde in glyoxal by AHMT spectrophotometry. The con-densation reaction was happen between formaldehyde and 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) in potassium hy-droxide solution medium, the condensation reaction products oxidized by potassium periodate into 6-mercapto-5-triazole (4,3-b) –S-tetrazine purplish red compounds. The maximum absorption wavelength was at 554 nm, When formaldehyde content was 0~1.4μg/mL, it had a good linear relationship with absorbance. The correlation coefficient was 0.9956. The relative standard deviation was 2.57%(n=6), the recovery of standard addition was 95.8%~108.7%.
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