Bintoro V P, Cantin-Esnault D, Alary J
Faculty of Pharmaceutical Sciences, Grenoble, Laboratory of Analytical Chemistry, La Tronche, France.
Food Addit Contam. 1996 Jan;13(1):77-87. doi: 10.1080/02652039609374382.
In this paper, a rapid and simple enzymic method is described for the determination of nitrate in 32 fresh and five dry Indonesian milk samples, deproteinized by Carrez reagents. Interference from albumin, casein, lactose and chloride ions was controlled. The calibration graph was linear over the range l-12.5 micrograms/ml NO3-; r = 0.9998. The limits of detection and quantification were found to be 0.45 micrograms/ml NO3- and 1 microgram/ml NO3- respectively. Standard nitrate solutions (10 micrograms/ml NO3-) were used to evaluate the precision. The results showed an average of 10.1 micrograms/ml, a standard deviation of 0.3 and a relative standard deviation of 3.4%. Adequate agreement was found between results obtained by the enzymic method and those of the French official reduction/photometric reference method (AFNor). Good recoveries (100% +/- 5%) were found for nitrate added to milk. The nitrate levels were in the range 1-2.6 mg/kg NO3- for fresh milk and 1.1-18 mg/kg NO3- for dry milk. All the results are in good agreement with those previously published for UK and American milk.
本文描述了一种快速简便的酶法，用于测定32份新鲜和5份干燥的印度尼西亚牛奶样品中的硝酸盐含量，样品用Carrez试剂进行了脱蛋白处理。控制了白蛋白、酪蛋白、乳糖和氯离子的干扰。校准曲线在1-12.5微克/毫升NO3-范围内呈线性；r = 0.9998。检测限和定量限分别为0.45微克/毫升NO3-和1微克/毫升NO3-。使用标准硝酸盐溶液（10微克/毫升NO3-）评估精密度。结果显示平均值为10.1微克/毫升，标准偏差为0.3，相对标准偏差为3.4%。酶法所得结果与法国官方还原/光度参考方法（AFNor）的结果有充分的一致性。向牛奶中添加硝酸盐后回收率良好（100%±5%）。新鲜牛奶中硝酸盐含量范围为1-2.6毫克/千克NO3-，干牛奶中为1.1-18毫克/千克NO3-。所有结果与先前发表的英国和美国牛奶的结果高度一致。
