A Novel Spectroscopic Approach for Vaseline Quality Discrimination

Vaseline, also referred to as petrolatum, is a colloidal dispersion of liquid-crystalline structures of hydrocarbons derived from petroleum. It has long been recognized for its versatile applications in the pharmaceutical industry, with its use in the formulation of various topical medications, wound care products, and drug delivery systems. For pharmaceutical use, petrolatum has to meet the quality standards described in its Pharmacopoeia monograph. The comprised test ranges allow for a broad range of Vaseline qualities on the market, while the tests themselves only poorly discriminate between grades. The only differentiating properties are related to the melting behavior, which is tested via drop point analysis, and the consistency, addressed in the functionality-related characteristics section. In this study, we propose the hypothesis that Near-infrared spectroscopy (NIRS) could be a comparably simple method to evaluate the crystalline behavior of Vaseline qualities. We expect such information to provide additional details for Vaseline quality discrimination. This discrimination would allow the most suitable petroleum jelly to be selected for an existing formulation when the previous one needs to be replaced; for example, due to a manufacturer change. We demonstrate that NIRS in transmission and reflectance mode obtained by traditional continuous spectra acquisition and fragmented NIR spectra acquisition through multi-optical, multi-modal excitation, respectively, can both serve as a basis for detecting Vaseline quality differences, which we have further proven by thermal analysis and tests with semisolid formulations. Additionally, we demonstrate that a lower-cost multi-optical spectrometer in reflectance mode can detect Vaseline quality differences in rotated samples.