Simultaneous determination of twenty amino acids and six carbohydrates in soy sauce by ion chromatography with integrated pulsed amperometric detection

Abstract

A method of gradient elution ion chromatography with integrated pulsed amperometric detection for simultaneous determination of twenty amino acids and six carbohydrates in soy sauce was established. The effects of column temperature, pH value of solution, and standing time were studied, and then the suitable gradient elution conditions were found for the determination. In the conditions that the flow rate is 0.25 mL/min, pH value of solution is in the range of 5.2-6.7, temperature of column is 35℃, the linear relationships of the 26 components are good and the correlation coefficients are not less than 0.995. Except glutamine, leucine, isoleucine and methionine, the limits of detection (S/N=3) of the other 22 components are less than 0.03 mg/L. The recoveries of the 26 components in soy sauce are 84.2%-109% at the spiked levels of 0.20, 0.50, 2.00 mg/L, and the relative standard deviations (RSDs) are in the range of 2.7%-7.8%. The method is efficient, easy, sensitive, and accurate for simultaneous determination of amino acids and carbohydrates in soy sauce, and can provide an effective research technique for adulterated soy sauce.