Simultaneous determination of 7 kinds of preservatives and saccharin in foods with HPLC, and identification with LC/MS/MS

Abstract

A simultaneous determination method of saccharin (SA), sorbic acid (SOA), benzoic acid (BA), p-hydroxybenzoic acid ethyl (PHBA-Et), p-hydroxybenzoic acid isopropyl (PHBA-isoPr), p-hydroxybenzoic acid propyl (PHBA-Pr), p-hydroxybenzoic acid isobutyl (PHBA-isoBu) and p-hydroxybenzoic acid butyl (PHBA-Bu) in foods by HPLC was examined. A mixture of acetonitrile-water (1:1) was used to extract these additives from foods excluding liquid foods, while acetonitrile was used to extract them from liquid foods. HPLC was performed using a TSKgel ODS80Ts (4.6 mm i.d.×150mm) column with a mobile phase of 0.01% formic acid solution containing 2 mmol/L-di-n-butyl (or amyl) ammonium acetate (A) and acetonitrile (B) under the following conditions: A/B=8 : 2 (0-8 min)→6 : 4 (15-32 min). Recoveries of these additives spiked in foods were 78-120%. The determination limits were 10μg/g. As the identification method, examination by liquid chromatography with electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) was used. Unknown compounds were identified by detection of product ions from their precursor ions in the negative mode with multiple reaction monitoring, m/z 182 > 106 for SA, m/z 121 > 77 for BA, m/z 111 > 67 for SOA and m/z 165 > 92 for PHBA-Et. Ratios of intensity of m/z 179 > 137 to m/z 179 > 92 were used for identification of isomers PHBA-isoPr and PHBA-Pr, and the ratios of intensity of m/z 193 > 137 to m/z 193 > 92 were used for isomers PHBA-isoBu and PHBA-Bu, because these isomers have very similar retention times on HPLC.