Lack of genotoxic effect of food dyes amaranth, sunset yellow and tartrazine and their metabolites in the gut micronucleus assay in mice.

The food dyes amaranth, sunset yellow and tartrazine were administered twice, at 24h intervals, by oral gavage to mice and assessed in the in vivo gut micronucleus test for genotoxic effects (frequency of micronucleated cells) and toxicity (apoptotic and mitotic cells). The concentrations of each compound and their main metabolites (sulfanilic acid and naphthionic acid) were measured in faeces during a 24-h period after single oral administrations of the food dyes to mice. Parent dye compounds and their main aromatic amine metabolites were detected in significant amounts in the environment of colonic cells. Acute oral exposure to food dye additives amaranth, sunset yellow and tartrazine did not induce genotoxic effect in the micronucleus gut assay in mice at doses up to 2000 mg/kg b.w. Food dyes administration increased the mitotic cells at all dose levels when compared to controls. These results suggest that the transient DNA damages previously observed in the colon of mice treated by amaranth and tartrazine by the in vivo comet assay [Sasaki, Y.F., Kawaguchi, S., Kamaya, A., Ohshita, M., Kabasawa, K., Iwama, K., Taniguchi, K., Tsuda, S., 2002. The comet assay with 8 mouse organs: results with 39 currently used food additives. Mutat. Res. 519, 103-119] are unable to be fixed in stable genotoxic lesions and might be partly explained by local cytotoxicity of the dyes.

Optimisation of probe concentration in indirect photometric detection in capillary electrophoresis using highly absorbing dyes.

In indirect photometric detection in capillary electrophoresis, the concentration of the absorbing probe ion in the background electrolyte should be as high as possible in order to increase the dynamic range of the detection method. For relatively low absorptivity probes (epsilon < 2000 L mol(-1)cm(-1)) used under typical conditions (75 microm ID capillary) the maximum probe concentration is normally limited by the separation current. However, for medium (epsilon approximately/= 2000-15000 L mol(-1)cm(-1)) and especially for high (epsilon > 15000 L mol(-1)cm(-1)) absorptivity probes such as dyes, the maximum concentration may be limited by the background absorbance of the electrolyte which must fall within the linearity range of the detector. In this work, it is shown that another practical factor limiting the probe concentration is the adsorption of probe onto the capillary wall at higher concentrations, resulting in unstable baseline and increased noise. Use of a zwitterionic surfactant to suppress adsorption enabled the concentration of a model probe anion (tartrazine) to be increased by a factor of six times (to 3 mM). This resulted in significant improvements in peaks shapes, resolution between peaks, detection sensitivity and linear calibration range for the analyte anions. Baseline separation of a test mixture was maintained up to 7.5 mM total concentration of sample coions injected (13.7 nL) for the 3 mM electrolyte, with detection limits ranging from 0.63 to 0.94 microM. Peak height reproducibility (over 20 consecutive injections) was improved (values ranging from 1.1 to 1.9%) compared with electrolytes containing lower concentrations of the probe. Overall, the optimised, higher concentration probe electrolyte provided the sensitivity benefits of highly absorbing probes with the additional benefits of ruggedness and improved stacking, peak shapes and resolution.