Comparison of near-infrared and laser-induced breakdown spectroscopy for determination of magnesium stearate in pharmaceutical powders and solid dosage forms.

Near-infrared (NIR) spectroscopy has become well established in both the pharmaceutical arena and other areas as a useful technique for rapid quantitative analysis of solid materials. Though laser-induced breakdown spectroscopy (LIBS) has not been widely applied in the pharmaceutical industry, the technique has been used for rapid quantitative analysis of solids in many other applications. One analysis amenable to each technique is the determination of magnesium stearate in solids during the lubrication blending unit operation of pharmaceutical processing. A comparative study of the utility of these two techniques for this application will be presented. Necessary sample preparations and the extent and type of matrix effects will be discussed. Additionally, it will be shown that NIR provides better accuracy and precision than LIBS with the experimental parameters used; however, LIBS showed superior selectivity as it was demonstrated to be more robust to sample matrix perturbations. Examples of blending applications will also be presented.