RESUMEN
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. A seven-factor partial least square regression (PLS) of the second derivative spectra encompassing the wavelength region of 1450-2200 nm was used to quantify both selamectin and moisture content. A second three-factor PLS solely for water content was also applied and compared with the full model. This qualification confirms that this method may be used to quantitate selamectin and moisture as a process tool or to examine finished good samples. Each sample can be rapidly analyzed within 5 min on the current bench top system.