Sensitive determination of erythrosine and other red food colorants using capillary electrophoresis with laser-induced fluorescence detection.

Capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was applied to separation and sensitive determination of red food colorants. Diode pumped frequency-doubled Nd:YAG laser (532 nm) was used as an excitation source in a laboratory-built CE-LIF system. For highly fluorescent erythrosine B (E127), an extrapolated limit of detection (LOD) of 0.4 ng mL(-1) (S/N=3) was achieved. Extrapolated LODs of other tested red additives, such as carmoisine, E122 (0.5 microg mL(-1)); amaranth, E123 (0.2 microg mL(-1)); ponceau 4R, E124 (0.3 microg mL(-1)) and red 2G, E128 (0.3 microg mL(-1)) were about one-order lower compared to results obtained with CE with absorbance detection in UV/vis (CE-UV/vis). The main advantages of using CE-LIF for analysis of food samples are high selectivity and minimization of matrix effect. To our knowledge, this is the first use of CE-LIF for determination of red food colorants.