连续流动分析-盐酸萘乙二胺分光光度法测定酱油中的亚硝酸盐和硝酸盐

建立了一种同时测定酱油中亚硝酸盐和硝酸盐的连续流动分析-盐酸萘乙二胺分光光度法。酱油样品经25 ℃超声15 min预处理，乙酸锌-亚铁氰化钾体系沉淀蛋白质后，自动进样且采用气泡隔断样品，并经透析膜透析，采用双通道同时测量亚硝酸盐和硝酸盐。结果表明，亚硝酸盐在0.025～1.0 mg/L质量浓度范围内线性良好，加标回收率在83.54%～98.56%之间，精密度试验结果相对标准偏差（RSD）＜3%；硝酸盐在0.25～5.0 mg/L质量浓度范围内线性良好，加标回收率在92.95%～102.32%之间，精密度试验结果RSD＜2%。该方法准确、高效、灵敏，可以用于测定酱油中亚硝酸盐和硝酸盐。

Determination of nitrite and nitrate in soy sauce by continuous flow analysis-N-ethylenediamine dihydrochloride spectrophotometry

A method for the simultaneous determination of nitrite and nitrate in soy sauce by continuous flow analysis-N-ethylenediamine dihydrochloride spectrophotometry was established. The soy sauce samples were pretreated with ultrasound at 25 ℃ for 15 min. After the protein was precipitated by zinc acetate and potassium ferrocyanide, the samples were injected automatically, and separated by bubbles. The nitrite and nitrate were determined simultaneously by double channels after dialysis with dialysis membrane. The results showed that nitrite had good liner relationships in the range of 0.025-1.0 mg/L, the standard recovery rate was ranged from 83.54% to 98.56%, and the relative standard deviation (RSD) of precision test results was less than 3%. The nitrate also had good liner relationships in the range of 0.25-5.0 mg/L, the standard recovery rate was ranged from 92.95% to 102.32%, and the RSD of precision test results was less than 2%. The method was accurate, efficient and sensitive, which could be used for the determination of nitrite and nitrate in soy sauce.