Sensitive determination of food colorant erythrosine and other xanthene dyes by CE-LIF
| Authors | |
|---|---|
| Year of publication | 2005 |
| Type | Article in Proceedings |
| Conference | Book of Abstracts - 11th International Symposium on Separation Sciences 2005 |
| MU Faculty or unit | |
| Citation | |
| Field | Analytic chemistry |
| Keywords | CE-LIF; food colorant; erythrosine |
| Description | In this work, sensitive determination of erythrosine and other xanthene dyes with absorption maxima above 500 nm based on fluorescent properties of the compounds has been suggested. The method involves extremely selective analysis of erythrosine (E127) in excess of other commonly used red food colorants. Concentration of the dye can be determined in presence/excess of other red dyes using capillary electrophoresis with laser induced fluorescence detection (CE-LIF) because of weak fluorescence of both synthetic xanthen and natural colorants in this region. LIF detector combined with a separation method can be used to detect extremely low amounts of analytes [6, 7] but the method is limited by analyte fluorescent properties, such as suitable excitation and emission wavelengths, quantum yield, etc. First, the fluorescent properties of the chosen colorants were determined using a spectrofluorimeter. Here, a home-built CE-LIF instrument [8] with solid state diode pumped frequency-doubled Nd:YAG excitation laser (532 nm) and a commercial CE instrument with absorbance detection were used. Separation was performed in fused silica capillary with i.d. 50 Ým, effective length 30 cm and total length 37 cm. The detection limit of the CE-LIF demonstrated for rhodamine B was 1x10-12 mol/l. For erythrosine B and eosine B, the detection limits of 5x10-10 mol/l and 2x10-9 mol/l, respectively, were calculated, using 20 mmol/l borate buffer (pH 8.5). Also the differences between CE-LIF and CE-UV/VIS determination of a selected dyes will be discussed. CE-LIF determination of erythrosine in real samples, like tin cherries, will be presented. |
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