离子色谱法测定食品中的无机铵

建立一种离子色谱法(IC)快速测定食品中铵根离子含量。样品用水浸泡并混匀,加入乙酸酸化,乙腈沉降蛋白,并一起通过冷冻离心去除脂肪,取适量上清液挥干后用1.0mL水复溶,过膜后备用。以H2SO4溶液梯度淋洗,淋洗液流速为1.0mL/min,采用DIONEX IonPac CS12A色谱柱分离,带抑制器的电导检测器检测,外标法定量。结果表明:NH4+的线性范围为0.1～20.0mg/L,线性相关系数R2大于0.995,检测限(LOD)为0.05mg/kg,定量限(LOQ)为0.1mg/kg,加标回收率为74%～110%,其相对标准偏差(RSD)小于5%。该方法简便,灵敏,准确,适用于多种食品中微量铵根离子的检测。

Studies on determination of inorganic ammonia in foods by ion chromatography

A new method of ion chromatography(IC) was developed for the determination of inorganic ammonia in foods.Samples were soaked and mixed in water,acidified by acetic acid,and proteins were precipitated by adding acetonitrile and removed with fat by freezing centrifugation.Then the quantitative supernatant was evaporated to dry and the residues were filtrated with membrane and reserved for analysis after dissolved in 1mL water.The H 2 SO 4 solution was selected as the gradient elution at a flow rate of 1.0mL/min.The sample solution was separated by column DIONEX IonPac CS12A,and then detected by conductivity detector with suppressor.And external standard curve was used for the need of quantitative analysis.Results : The linear range of the method for NH + 4 was 0.1～20.0mg/L,and the linear correlation coefficient R 2 was more than 0.995.The limit of detection(LOD) was 0.05mg/kg and the limit of quantitation(LOQ) was 0.1mg/kg.The recoveries were 74%～110% with the relative standard deviations(RSDs) less than 5%.Actual test results showed that the method was simple,sensitive and accurate,and was suitable for trace determination of NH + 4 in many foods.