Use of near-infrared spectrometry for quantitative determinations of selamectin and moisture in topical formulations.

A rapid near-infrared spectrometric (NIR) method was qualified for use with the quantitative analysis of selamectin and moisture in topical formulations. Selamectin is currently marketed as a pet endectocide and is available in several formulations for cats and dogs. The use of NIR in this investigation replaces the in-process testing by liquid chromatography and concurrently provided moisture content that would otherwise only be available with additional Karl Fischer titration investigations.