2,4-二硝基苯肼比色法测定食品中甲醛的改进

Improvement of determining formaldehyde in food by 2,4-dinitrophenylhydrazine colorimetric method

通过改进2,4-二硝基苯肼比色法测定食品中甲醛的不足,对显色条件进行了优化,并评价了方法的性能指标,对市售腐竹、米粉、毛肚三种食品中的甲醛含量进行了测定分析。建立一种将甲醛衍生成甲醛-2,4-二硝基苯腙,甲醛-2,4-二硝基苯腙与强碱作用生成酒红色的醌类物质,进行吸光度值的测定的方法。试验方法：甲醛溶液与2.8 m L 2,4-二硝基苯肼乙醇饱和溶液在酸性条件下于50℃水浴衍生30 min,冷却室温,先后加入无水乙醇、KOH-乙醇溶液,稳定10 min在432 nm波长下测得吸光度值。结果表明：甲醛标准曲线的线性方程为Y=0.6788X＋0.0102,相关糸数R 2=0.999,线性范围为1~12μg/m L;平均回收率为102.8%（RSD=3.99%）;最低检出限为0.0025μg/m L。结论：改进的方法灵敏、准确、精密度高,能够满足食品中甲醛分析准确度的要求。

By improving 2, 4 dinitrophenylhydrazine colorimetric method for detecting trace formaldehyde in food, the coloration conditions were optimized, the performance of analysis were evaluated, the content of formaldehyde in Yuba, MaoDu, rice noodles were measured and analyzed. A method using formaldehyde-2, 4-two nitrobenzene hydrazone derivatives, formaldehyde-2, 4-two nitrobenzene hydrazone and alkali to generate a red wine color quinone to determine the absorbance value was established. Test method .. formaldehyde solution and 2.8 mL 2, 4-twodinitrophenylhydrazine ethanol saturated solution under acidic conditions reacted for 30 min at 50 ℃ water bath, then cool down to room temperature, adding anhydrous alcohol, KOH- ethanol solution, reacted for 10 min and measured the absorbance value at 432 nm wavelength. The results show that .. the linear equations of formaldehyde standard curve was Y=0.6788X＋0.0102, linear correlation coefficients （R2） was 0.999, linear range was 1 - 12 μg/ mL ^-1 the average recovery was 102.8% with relative standard deviation of 3.99% ,the minimum detection limit was 0.0025 μg/mL. Conclusion .. The method is high precisive, sensitivity and accuracy, and can meet the requirements of formaldehyde analysis in the food.