Simultaneous Determination of Eight Organic Acids in Grape Wines by Capillary Electrophoresis-Electrospray Ionization Mass Spectrometry

A capillary electrophoresis-electrospray ionization mass spectrometry (CE-ESI-MS) method for the simultaneous determination of oxalic, fumaric, succinic, citric, malic, ascorbic, tartaric and tartaric acid in grape wines was established. The samples were separated by an uncoated capillary(50 μm×80 cm) on the operating voltage of 25 kV using 40.0 mmol/L ammonium acetate (pH 4.5) as the running buffer and 30% 2-propanol-70% water mixture(containing 3 mol/L ammonia) as the sheath liquid. The baseline separation of eight compounds was achieved within 15 min with satisfactory repeatability and sensitivity. The linear ranges are 1.0—300.0, 1.0—300.0, 5.0—1 500.0, 2.0—600.0, 5.0—1 500.0, 1.0—300.0, 5.0—1 500.0 and 5.0—1 500.0 mg/L for oxalic, fumaric, succinic, citric, malic, ascorbic, tartaric and tartaric acid with detection limits of 0.2, 0.05, 1.0, 0.5, 1.0, 0.3, 1.0, 1.0 mg/L, respectively. The average recoveries of the eight components are 87.6%—98.2% with the RSDs of 2.7%—5.6%.