Liquid chromatographic determination of cholecalciferol in rodent baits

Cholecalciferol (vitamin D3) is extracted in acetonitrile on a Goldfisch apparatus, diluted to volume, and determined by reverse phase liquid chromatography (LC). The sum of the peak heights of pre-vitamin D3 and cis-vitamin D3 is used for quantitation. The method was tested for precision, linearity, and recovery. Quadruplicate analyses of 5 formulation samples gave relative standard deviations of 1.56-2.65%. Linearity was excellent with regression and correlation coefficients of 0.9997 and 0.9998, respectively. Recovery was 98.0 +/- 2.7%. The method is applicable to 0.075% cholecalciferol rodent baits.