催化动力学光度法测定腐竹中的痕量甲醛

Catalytic-kinetic Photometric Determination of Trace Formaldehyde in Yuba (Dried Beancurd Stick)

基于在硫酸介质中,甲醛对高碘酸钾氧化甲基红有较强的催化作用,建立测定腐竹中痕量甲醛的新方法。研究影响催化褪色反应速度的条件。在最优化条件下,甲醛浓度在2.25×10-4～1.35×10-2μg/ml范围内与吸光度呈良好的线性关系,方法的检出限为4×10-5μg/ml。对浓度为0.0041μg/ml的甲醛标准溶液进行11次平行测定,得相对标准偏差(RSD)为0.1%。该法具有灵敏度高、选择性好等特点。用于腐竹中痕量甲醛的测定,回收率为93%～106%,结果令人满意。

Based on the catalytic effect of formaldehyde on the reaction between potassium periodate and methyl red, a new catalytic-kinetic photometric method for the determination of trace formaldehyde was developed in the present study. The factors affecting the rate of catalytic fading reaction were investigated. Under the optimal conditions, the formaldehyde concen- tration within a range of 2.25×10^-4 to 1.35 ×10^-2 μg/ml had a good linear relationship with absorbance at 516 nm, the detection limit was 4 × 10^-5 μg/mi, and the relative standard deviation （RSD） was 0.1% for determining 0.0041 μg/ml formaldehyde solution （n = 11）. The method had high sensitivity and selectivity. When it is applied in the detection of trace formaldehyde in yuba, the spike recoveries were between 93% and 106%.