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A new enrichment and sensitive determination method, which includes HPLC-DAD analysis after Magnetic Based Solid Phase Extraction (MSPE), has been developed for trace analysis of Sibutramine molecules in herbal slimming tea samples. In the proposed method, Sibutramine molecules were pre-concentrated by using a newly synthetized magnetic sorbent in our laboratory. Desorption of Sibutramine molecules from sorbent phase were carried out by using acetonitrile/methanol (1:1) solvent in the presence of pH 8.0 buffer before chromatographic determinations. Analytical parameters of method such as linear range, enrichment factor, and determination limit were determined after optimizing experimental variables such as interaction time, desorption solvent, pH, etc. Sibutramine molecule was analyzed by isocratic elution of acetonitrile and KH2PO4 (pH 3.0, 0.05 M) (40:60) with DAD detector at 223 nm wavelength. Limit of detection (LOD) value was calculated as 1.43 ng mL− 1. Relative standard deviations (RSD) were below 3.20% for determinations of model solutions including 200 ng mL− 1 of Sibutramine. Finally, the developed method has been applied to herbal slimming tea samples with quantitative in recovery experiments.

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Background: A new enrichment and sensitive determination method, which includes HPLC-DAD analysis after Magnetic Solid Phase Extraction (MSPE), has been developed for trace analysis of Sibutramine molecules in herbal slimming products. Sibutramine is one of the most adulterated drug molecules in herbal products. Method: In the proposed method, Sibutramine molecules were pre-concentrated by using Fe3O4@MPTMS-Dithizone magnetic sorbent synthesized in our laboratory. Desorption of Sibutramine molecules from the sorbent phase was carried out by using acetonitrile: methanol (1:1) solvent in the presence of pH 8.0 buffer before chromatographic determinations. Results: Analytical parameters of the method, such as linear range, enrichment factor, and determination limit, were determined after optimizing experimental variables such as interaction time, desorption solvent, pH, etc. The sibutramine molecule was analyzed by isocratic elution of acetonitrile and KH2PO4 (pH 3.0, 0.05 M) (40:60) with a DAD detector at 223 nm wavelength. Limit of detection (LOD) value was calculated as 1.43 ng mL-1. Conclusion: Relative standard deviations (RSD) were below 3.20 % for determinations of model solutions, including 200 ng mL-1 of Sibutramine. Finally, the developed method has been applied to herbal slimming tea samples with quantitative recovery experiments.

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