Quantitative Determination of Alpha-Lipoic Acid in SLS Micellar Medium Utilizing Inhibitory Kinetic Approach

A novel, repeatable, and swift kinetic approach for determining alpha-lipoic acid (ALA) in sodium lauryl sulfate (SLS) micellar medium has been presented, and it has been connected to ALA determination in drug formulations. The approach is based on ALA inhibitory property. ALA (containing two sulfur atoms) forms a chelate with Hg۲+, lowering the effective [Hg(II)], and ultimately, the Hg۲+ catalyzed cyanide substitution rate from [Ru(CN)۶]۴- by nitroso-R-salt (N-R-salt). Fixed times of ۵ and ۱۰ minutes were chosen under optimal reaction conditions with [N-R-salt] = ۰.۴۵ mM, pH = ۷.۰ ± ۰.۰۲, Temp = ۴۵ ± ۰.۲ °C, I = ۰.۱ M (NaClO۴), [Ru(CN)۶۴-] = ۴۲.۵ µM, [Hg+۲] = ۰.۲۵ mM, and [SLS] = ۸.۵ mM to calculate the absorbance at ۵۲۵ nm associated with the final substitution product [Ru(CN)۵ N-R-salt]۳-. ALA's inhibiting influence on the Hg۲+ catalyzed cyanide substitution with N-R-salt from [Ru(CN)۶]۴-, has been represented by a modified mechanistic approach. The concentration of ALA in various water specimens can be measured at the micro-level down to ۲.۵ µM using the established kinetic spectrophotometric approach. The suggested method is highly reproducible and has been effectively applied to accurately quantify the ALA in pharmaceutical samples. Even as much as ۱۰۰۰ with [ALA], Excipients used in medications do not significantly hinder the determination of ALA.

کلیدواژه ها:

Inhibitory kinetic approach ، Alpha-lipoic acid ، SLS micellar medium ، Pharmaceutical samples ، Excipients