Abstract: A high performance capillary electrophoresis (HPCE) method has been established for the separation of Brilliant Blue and Amaranth in carbonated beverages. Sunset Yellow was added into the sample as the internal standard. The separation was carried out on a fused-silica uncoated capillary column (40 cm×75 μm). The sample was injected by air pressure injection (14 kPa×3 s) at room temperature. The analysis was completed in 10 mmol/L Na2HPO4 buffer (pH 8.56) at 20 kV of separation voltage and 390 nm of detection wavelength. The relative correction factors of Brilliant Blue and Amaranth were 0.8329 and 1.2253, and the relative standard deviations (RSDs) were 3.3% and 2.6%, respectively. The respective quantification limits (S/N=10) were 1.629 mg/L and 4.160 mg/L, the recoveries were in the ranges of 97.87%~102.1% (RSD=1.8%) and 94.07%~103.8% (RSD=4.1%), and the method precisions were 3.2% and 2.0%. The optimization of the pretreatment made the method more suitable for the determination of Brilliant Blue and Amaranth in carbonated beverages by capillary electrophoresis. The systematic error brought by the background was eliminated basically by using the blank sample as the base solution. The relative factors of Brilliant Blue and Amaranth were reproducible in the ranges of 1.629~228.8 mg/L and 4.16~401.6 mg/L, respectively. So this method can be used to quantify the two synthetic pigments in carbonated beverages accurately.

Key words: Amaranth, Brilliant Blue, drinks, internal standard method, high performance capillary electrophoresis (HPCE)