Single-laboratory validation of an NMR method for the determination of aloe vera polysaccharide in pharmaceutical formulations

Abstract

This report presents a single-laboratory-validated NMR method for determining the quantity of aloe vera polysaccharide in product formulations. The ratio of signal intensities of the acetyl methyl protons to methyl protons of an internal reference varied linearly with concentration (r2 > 0.99) with a lower LOQ of 0.2 g/100 mL for two commercial aloe polysaccharide standards, Acemannan Hydrogel (AH) and lmmuno-10 (1-10). The assay was used to quantify these standards in two nonacetylated polysaccharide matrices, dextrin and arabinogalactan, and in a pharmaceutical product. The concentrations of AH in samples containing the polysaccharide matrices agreed within 7% of values determined on the basis of weight and showed within-and between-run RSD values of <3.5%. The assay of I-10 in the pharmaceutical product was within 7% of the expected values over a range from 50 to 125% of the targeted I-10 concentration, with a between-run RSD of <7%. The assay showed no interference from other added polysaccharides or from other components of the pharmaceutical formulation and was independent of the molecular size distribution of the aloe polysaccharide present. The NMR assay can be used to validate aloe polysaccharide contained in a product and to follow any chemical degradation that may occur over time.