Simultaneous determination of inorganic anions and cations in wine by capillary electrophoresis-indirect ultraviolet detection with ionic liquid as background electrolyte

Abstract

A novel method was developed for the simultaneous determination of inorganic anions (Cl-, SO42- and ClO3-) and cations (K+, Ca2+, Na+, Mg2+ and Li+) in wine by capillary electrophoresis-indirect ultraviolet detection (CE-UV) with dual-opposite end injection using 1-ethyl-3-methylimidazolium p-toluenesulfonate ([EMIm]TS) as the background electrolyte.[EMIm]TS acted as the running electrolyte and probe, generating the background signals for cations and anions under indirect UV light, consequently simplifying the electrophoretic medium. Under the optimal experimental conditions, baseline separation was achieved for the eight inorganic ions within 6.5 min. The linear ranges of the eight inorganic ions were 0.005-0.7 g/L, with correlation coefficients (R2) of 0.963-0.995. The limits of detection (LODs) were between 1.2 and 12.5 mg/L at a signal-to-noise ratio of 3 (S/N=3). Eight inorganic ions were detected in three different brands of wines obtained from supermarket. Good recoveries of 90.1%-110.5% at three spiked levels (0.05, 0.2 and 0.4 g/L) were achieved with a low relative standard deviations (RSDs) (n=5) of 1.1%-4.8%. The proposed method is robust and reliable for the sensitive and rapid analysis of the inorganic anions and cations, and it has potential in evaluating the quality of wine.