建立了充氮蒸馏-甲醛吸收-副玫瑰苯胺比色法测定食用菌中亚硫酸盐的检测方法。探讨了蒸馏时间、充氮、及N2流量等因素对检验结果的影响,并与国家标准检验方法进行对比实验,及组织5家经过资质认证的实验室对本方法进行精密度试验。实验结果显示:本方法的线性范围为0～20μg;称取2 g样品时,SO2的最小检出量为0.08 mg/kg;方法的精密度(RSD)为1.2%～7.8%;实际样品加标回收率为83.1%～99.2%。适宜的蒸馏时间为25 min;蒸馏充氮可使检测结果提高9%～19%;N2流量宜为0.5～0.6 L/min。本方法与国标法的检测结果差异不显著。与国标法相比,本方法具有样品提取液无颜色干扰、灵敏度高及环境污染少的优点。

A spectrophotometry method for determination of sulfite contents in edible fungus was successfully established and compared with the published National Standard Method(NSM).The method involves nitrogen distillation followed by formaldehyde absorbing and parasosaniline colorimetry.The effects of distillation duration,nitrogen presence and flow rate on testing results were also investigated.The linear range of the calibration curve for sulfite was 0-20 μg.The sulfite detection limit was 0.08 mg/kg with 2.0 g of samples.The relative standard deviation of the proposed method ranged from 1.2 % to 7.8 %.The recovery rate was between 83.1% ～ 99.2%.The most suitable distillation duration was 25 min.Use of nitrogen could improve detection sensitivity by 9-19 %,and the optimal nitrogen flow rate was 0.6-0.6 L/min.This newly established method was validated by 5 licensed laboratories for accuracy.The reported new method has advantages of higher sensitivity,less interference from sample colors and environmental hazards when compared to the NSM.