Liquid chromatographic determination of benzoic acid in orange juice: interlaboratory study

An interlaboratory study was carried out for the determination of benzoic acid in orange juice by liquid chromatography. The orange juice was fortified with 0.5-10 ppm benzoic acid. Statistical analysis of the results showed that relative reproducibility (RSDR) between laboratories ranged from 6.92 to 15.97% for juice fortified with 1-10 ppm benzoic acid; RSDR was 27.90% for juice fortified with 0.5 ppm benzoic acid. Mean recoveries ranged from 94.5% for 4 ppm benzoic acid to 114% for 0.5 ppm benzoic acid. Total variability increased with increasing fortification level as measured by standard deviation for reproducibility (SR).