Abstract:

Based on the catalytic effect of cobalt (II) on the oxidation of benzoic acid by potassium bromate in NaH2PO4-Na2HPO4 buffer solution at the condition of pH 8, a new catalytic oxidation fluorometry method was proposed for the indirect determination of benzoic acid. Under optimal determination conditions, an excellent linear relationship between benzoic acid concentration within a range of 5×10-7－3×10-5 g/mL and fluorescence intensity was observed. The detection limit of this established method was 2×10-8 g/mL. The reproducibility experiments revealed the relative standard deviation (RSD) of 1.9% for benzoic acid solution at the concentration of 1×10-6 g/mL. This established method has been applied for the detection of benzoic acid in vinegar and sauce. The recovery rates were in the range of 95.7%－101.6% with satisfactory results.

Key words: catalysis oxidation, fluorimetry, benzoic acid, preservative