Simultaneous Determination of Saccharine, Sorbic Acid, Benzoic Acid and Five Esters of p-Hydroxybenzoic Acid in Liquid Foods by Isocratic High-Performance Liquid Chromatography

An isocratic high performance liquid chromatographic (HPLC) method by using ion pair partition system was established for the simultaneous determination of saccharine (SA), sorbic acid (SOA), benzoic acid (BA) and five esters of p-hydroxybenzoic acid (PHBA) such as ethyl (PHBA-Et), isopropyl (PHBA-isoPr), n-propyl (PHBA-n-Pr), isobutyl (PHBA-isoBu) and n-butyl p-hydroxybenzoate (PHBA-n-Bu) in liquid foods. Liquid foods such as soy sauce, soft drinks and lactic acid bacteria beverages were pretreated with SEP-PAK C18 cartridge prior to HPLC analysis. SA, SOA, BA and the esters of PHBA could be separated within 30 min on a reverse phase column, Zorbax C8, with the eluent, ethanol-0.05 M sodium dihydrogenphosphate (34 : 66) containing 2 mM cetyltrimethylammonium chloride, adjusted to pH 4.4. The eluate was monitored at 240 nm. Recoveries of SA, SOA, BA, PHBA-Et, PHBA-isoPr, PHBA-n-Pr, PHBA-isoBu and PHBA-n-Bu from liquid foods were 98.0-101.1%, 95.8-100.2%, 97.0-100.8%, 98.0-99.4%, 97.6-100.5%, 95.2-99.8%, 98.8-101.5% and 95.0-101.4%, respectively. Their detection limits were 5 mg/kg, except 10 mg/kg for SA and 1 mg/kg for SOA.