Development and validation of a fast method for determination of free glycerol in biodiesel by capillary electrophoresis

In this study, a capillary electrophoresis (CE) methodology for the determination of free glycerol in biodiesel using oxidative cleavage with periodate was optimized and validated. The amount of iodate produced in the reaction was determined by CE. The optimized electrolyte was 20 mmol L(-1) glycine and 10 mmol L(-1) trifluoroacetic acid (direct UV detection, 210 nm). The short total analysis time (less than 28 s) was obtained using the short end injection mode. The optimization of the method was carried out using Peakmaster software. The choice of the components of the run electrolyte and of the internal standard (nitrate) was made through the use of effective mobility curves. A good correlation coefficient higher than 0.9991 and low LOD 4.3 mg L(-1) was obtained. The recovery of free glycerol was 95.4-102.4%. This method was used to determine glycerol in commercial biodiesel samples.