酱油中食盐含量测定方法的比较和改进

酱油中食盐含量的测定方法已有报道,主要有莫尔法、佛尔哈德法、电位滴定法、氯离子选择电极法等,根据已有的方法将莫尔法进行改进、且自行设计灰化法进行实验,并与上述方法测定的结果比较,发现酱油中食盐含量在22.2g/100mL和22.3g/100mL之间。比较几种方法的准确度和精密度发现,它们各有不同的特点,电位滴定法和氯离子选择电极法有较好的准确度和灵敏度且操作简便,但对温度等外界条件和操作要求严格;其余的方法均需脱色处理,操作较繁琐;改进后的莫尔法能很好的解决脱色问题,但误差较大测得值偏低;自行设计的灰化法操作简单可行并有较好的准确度。

Comparison and improvement of determination methods of salt content in soy sauce

The determination methods of salt content in soy sauce have been extensively reported.There are mainly Moore method,Volhard method,Potentiometric titration and chloride ion selective electrode method and so on.Based on these methods,Moore method was improved and Ashing method by self-designed was used in this paper to compare with the previous methods.The results showed that salt contents in soy sauce were between 22.2g/100ml and 22.3g/100ml.They had different characteristics in accuracy and precision: Potentiometric titration and chloride ion selective electrode method had better accuracy and sensitivity,and were simple but need high demand of external conditions and operation.The rest of the methods should be treated with decoloring and were more complicated.The improved Moore method was a good solution to solve the problem of decoration but had large errors in test results.In comparison,ashing method by self-designed had better accuracy and was easily operated.