Rapid ultraviolet spectrophotometric and liquid chromatographic methods for the determination of natamycin in lactoserum matrix.

Two rapid and simple methods were developed for the determination of natamycin in lactoserum matrix by ultraviolet (UV) spectrophotometry and liquid chromatography (LC) with diode-array detection. The methods involve protein precipitation with methanol, followed by centrifugation. No cleanup is necessary. The applicable concentrations of natamycin in lactoserum range from 2 to 500 mg/L for samples analyzed by both methods. The detection and quantitation limits are 0.07 and 0.23 mg/L, respectively, for the UV spectrophotometric method and 0.1 and 0.32 mg/L, respectively, for the LC method. The methods were applied satisfactorily to the determination of natamycin in various commercial lactosera. Both methods were validated independently by standard additions and Youden methodologies, which verified their accuracy. Once the 2 proposed methods were validated independently, the validation of one method was carried out with the other.