Determination of diethylene glycol in toothpaste by capillary electrophoresis with electrochemical detection

Diethylene glycol (DEG) can be determined in toothpaste via capillary electrophoresis at 16 kV using a fused silica capillary of 75 cm length and of 25 mu m diameter along with a copper disc electrode detector operated at + 0.65 V (vs. SCE). DEG, propylene glyco1 and glycerol in a running buffer of pH 9.2 were separated within 17 min. The linear range for DEG is from 840 to to 4.2 mu g center dot mL-1, and the detection limit (at S/N = 3) is 1.6 mu g center dot mL-1 which therefore meets the safety limit. When applied to the analysis of DEG in toothpaste, the recoveries are between 96.9 and 103.0% for spiked samples and thus are quite satisfactory.