Validation of the procedure for the determination of maduramicin in concentrates, premixes, and feeds by liquid chromatography.

A single laboratory validation was carried out for the determination of maduramicin in concentrates, premixes, and feed. The method comprised sample extraction of maduramicin, derivatization with dansylhydrazine and liquid chromatography with ultraviolet light detection. The limit of detection (LOD) and limit of quantification (LOQ) were 0.4 and 1.0 mg kg(-1), respectively. The repeatability expressed as the average difference between the results of duplicate measurements was 5.9% at the concentration level of 1% (concentrate), 7.1% at the concentration level of 1 g kg(-1) (premix), and 11% with the feed containing maduramicin with the nominal concentration of 5 mg kg(-1) and feed spiked at the concentration level of 1 mg kg(-1). The relative standard deviations for the within-laboratory reproducibility (RSD(W)) were 9.2%, 16%, 18%, and 17% at the concentration levels of 1%, 1 g kg(-1), 5 mg kg(-1), and 1 mg kg(-1), respectively. The measurement uncertainties were +/-0.2%, +/-0.3 g kg(-1), +/-1.9 mg kg(-1), and +/-0.3 mg kg(-1) at the same concentration levels, respectively.