Abstract: This study aimed to select and optimize a sample extraction method for the determination of nitrite from milk powder. The absorbance of the experimental water stored for different periods of time was detected by three extraction methods, heat extraction, ultrasonic extraction and ultrasonic decolorization. The color and spiked recoveries of the filtrates from the three methods were evaluated. The nitrite content of quality control samples was determined by ultrasonic decolorization and the limit of detection (LOD) of this method was investigated. The results indicated that storage time did not affect the absorbance of the experimental water. The recoveries of the ultrasonic decolorization method were over 90%, with relative standard deviations (RSD) less than 10%. and the measured results of the quality control samples were within the characteristic value range with LOD of 0.4 mg/kg, which meets the laboratory quality control requirements. The ultrasonic decolorization method has good accuracy and accuracy, and it is recommended that it be used for the decolorization of colored substances in the national standard method.

Key words: milk powder; nitrite; activated carbon; decolorization

摘要： 优化一种乳粉中亚硝酸盐的提取方法。采用加热提取法、超声提取法及超声脱色法3 种提取方法对不同放置时间实验用水的空白实验吸光度进行测定，分析3 种提取方法滤液颜色及加标回收率，采用超声脱色法测定质控样品中的亚硝酸盐含量和方法检出限。结果表明：不同放置时间的实验用水不会对空白实验吸光度产生影响；超声脱色法回收率均可达90%以上，相对标准偏差小于10%；质控样品检测结果在特性值区间内，检出限为0.4 mg/kg，符合实验室质控要求。超声脱色法检测结果精确度和准确度良好，建议国标方法中增加对有色物质的脱色处理。

关键词: 乳粉；亚硝酸盐；活性炭；脱色