High-performance liquid chromatographic determination of mono-, poly- and hydroxycarboxylic acids in foods and beverages as their 2-nitrophenylhydrazides

The application of direct derivatization in conjunction with high-performance liquid chromatography (HPLC) is described for the determination of both free and total carboxylic acids in foods and beverages. The method is based on the reaction of the carboxylic acids with 2-nitrophenylhydrazine hydrochloride, without complicated isolation steps, which produces their non-volatile hydrazine derivatives. The HPLC of a series of carboxylic acid groups was performed isocratically with short retention times. The analytical results showed good recovery and reproducibility using each internal standard. Due to its excellent selectivity and sensitivity, the present method can serve as a useful tool for routine determinations of mono-, poly- and hydroxycarboxylic acids in foods and beverages.