Determination of phloxine B and uranine in water by capillary zone electrophoresis

Phloxine B and uranine are color additives in drugs and cosmetics as well as potential photoactive insecticides. A capillary zone electrophoretic (CZE) method is developed to determine phloxine B and uranine in water. A fused-silica capillary (67 cm, 75-micron i.d.) and borate buffer are used. Migration of phloxine B and uranine increases slightly as the pH of the running buffer increases between the range of 8-9. Although there are only slight effects of ionic strength on the analyte migration in the range of 0-20 mM NaCl in the running buffer, the migration of phloxine B and uranine increases as the percentage of methanol in the samples increases. Methanol shows little effect on the quantitation of phloxine B and uranine. The CZE procedure is applied to determine phloxine B and uranine fortified in tap and stream water samples. Solid-phase extraction is employed to recover the analytes spiked in the water samples. Recoveries range from 87-112% for phloxine B spiked at 10-200 ppb in the tap and stream water. Uranine recoveries are 86-91% at fortification levels of 10-50 ppb in the water samples.