Green spectrophotometric methods for determination of a monosodium glutamate in different matrices

Abstract Two novel and simple spectrophotometric methods have been developed for the determination of monosodium glutamate (MSG). They are based on reaction of MSG with 1,2-naphthoquinone-4-sulfonate sodium (Method I) and ascorbic acid (Method II) to give colored products. To optimize the factors affecting each reaction, one factor at a time was used for method I while 23 full factorial design was used for method II. Beer's law was obeyed in ranges of 5–35 μg. mL−1 and 1–14 µg. mL−1 for methods I and II, respectively. The methods were extensively validated and successfully applied for the determination of MSG in food samples and in pediatric syrup using standard addition method. The results were also compared to a reported HPLC method using t-test and F-test at 95% confidence level showing no significant differences. Methods were assessed to have excellent greenness using analytical Eco-scale. The results of the methods have led to recommendations concerning safety margin of MSG and people that may be at risk. The developed methods are considered as bromatological tools for quantifying MSG in food. The presented methods are simple, easy, cost-effective and suitable for routine analysis in MSG in food and pharmaceuticals.