甲醛吸收-盐酸副玫瑰苯胺法测定食品中的亚硫酸盐

Measurement of sulfite in food by spetrophotometry using formaldehyde as stabilizer

目的：建立用甲醛溶液吸收-盐酸副玫瑰苯胺法测定食品中亚硫酸盐的方法。方法：样品中加入甲醛，样品中的二氧化硫与甲醛生成稳定的羟甲基磺酸加成化合物，加入氢氧化钠后，与盐酸副玫瑰苯胺作用，生成紫红色化合物，在波长560nm处用分光光度法测定食品中亚硫酸盐含量。结果：采用甲醛作为食品中亚硫酸盐的稳定剂，二氧化硫浓度在0～2．0μg／ml范围内与吸光值呈良好的线性关系（r=0．9998），方法的检出限为0．2mg／kg，定量限为1．2mg／kg。测定样品的相对标准偏差在3．3％～6．5％之间，回收率在89．5％～97．5％之间。与国标法测定结果进行比较，两者无显著性差异。结论：该方法操作简便，重现性好，线性范围宽，减小了对环境的污染，可用于食品中亚硫酸盐的测定。

Objective： A new spectrophotometry was established to measure sulfite in food by using formaldehyde as stabilizer. Methods：Sulfite was stabilized by adding formaldehyde into samples. Sulfur dioxide in samples reacted with formaldehyde to form steady hydroxymethylsulphonic acid. Adding sodium hydroxide, the compound reacted with pararosaniline hydrechloride to produce purple red compound, which was determined by spetrophotometry at 560 nm. Results：This method had good linearity（ r = 0. 9998 ） for the concentration of sulfur dioxide ranged from 0 to 2. 0 μg/ml. RSD of samples ranged from 3.3% to 6. 5%, the average recoveries of samples were between 89. 5% ～ 97.5%. The method detection limit was 0. 2 mg/kg, the limit of quantitation was 1.2 mg/kg. There was no significant difference between the results by this method and those by the national standard method. Conclusion：This method has good repeatability and less pollution and can be used in the determination of sulfite in food.