DETERMINATION OF OXALATE IN PARENTERAL-NUTRITION SOLUTIONS BY CAPILLARY ELECTROPHORESIS

A rapid, sensitive and reliable capillary electrophoretic (CE) method on indirect UV absorbance detection has been developed, optimized and applied to the separation and determination of low (mg/l) levels of ox alate in commercial parental nutrition preparations. The determinatin of oxalate requires no extraction, derivatization or other complex pre -analysis steps. The method used chromate as the UV-absorbing backgrou nd electrolyte and oxalate was detected indirectly at 254 nm. The anal ysis time for oxalate is just under 7 min per sample with oxalate migr ating at approximately 4 min. The method calibration curves were shown to be linear over a minimum of 1.5 orders of magnitude with a limit o f detection for oxalate of approximately 240 mu-g/l. The methods linea r dynamic range for oxalate was shown to extend over more than 2.5 ord ers of magnitude. The final optimized method was used to separate and quantify oxalate in parenteral nutrition solutions that had been submi tted to 24-h neonatal phototherapy.