Abstract:

A new method using suppressed high-performance ion chromatography was developed for the determination of benzoic acid in paprika oleoresin. The analysis was performed on a Dionex Ion Pac AS11 anion exchange column (250 mm×4 mm) with an AG11 guard column(50 mm×4 mm). The mobile phase was composed of 0.22 mol/L sodium hydroxide solution, water and 50% iso-propylacohol. After gradient elution the effluent was suppressed by an anion micromembrane suppressor and measured by a conductivity detector. The samples were precipitated with potassium hexaoyanoferrate and zinc acetate solution and filtered in turn by a filter paper and a membrane (0.45 μm) to remove other components. The results showed that the linear range for benzoic acid was 5.0－500 mg/L, with a detection limit of 1.5 mg/L and the correlation coefficient of linear regression equation was 0.9997; the RSD for 10 parallel determinations was 1.98%. The method was applied in the determination of benzoic acid content in paprika oleoresin with satisfactory results, and the recoveries for benzoic acid in paprika oleoresin spiked at three different levels were in the range of 97.6%－100.3%.

Key words: high-performance ion chromatography, suppressed conductivity, determination, benzoic acid, paprika oleoresin