Microspectrometric determination of sibutramine in an adulterated slimming formulation

Abstract

Validated methods for the quantification of sibutramine have been developed using spectrometry. The proposed methods are based on the condensation of malonic acid/acetic anhydride under the catalytic effect of the tertiary amine moiety in sibutramine. The resulting product was measured spectrophotometrically at 411 nm and also spectrofluorimetrically at 426 nm, after excitation at 381 nm. These methods were applied to the analysis of a laboratory prepared slimming product for the quantitative determination of illegally added sibutramine. The calibration curve area versus concentration was found to be linear in the ranges of 1–5 μg mL⁻¹ and 0.2–0.8 μg mL⁻¹ for the spectrophotometry and spectrofluorimetry, respectively. Both methods were validated for accuracy, precision, linearity, selectivity, recovery and short term stability. In conclusion, these methods were found to be useful for the routine analysis of illegally added sibutramine in marketed products.