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Mass Spectrometric Determination of the Predominant Adrenergic Alkaloids in Bitter Orange (Citrus aurantium)



B C. Nelson, Karsten Putzbach, Katherine E. Sharpless, Lane C. Sander


The predominant adrenergic alkaloid found in the peel and fruit of bitter orange, Citrus aurantium, is synephrine. Synephrine has thermogenic properties and is used as a dietary supplement to enhance energy and promote weight loss. However, there exists some concern that the consumption of dietary supplements containing synephrine or similar alkaloids may contribute to adverse cardiovascular events. This report documents the development and validation of a positive-ion mode liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the quantitative determination of the major (synephrine) and minor (tyramine, N-methyltyramine, octopamine and hordenine) adrenergic alkaloids in a suite of National Institute of Standards and Technology (NIST) bitter orange Standard Reference Materials (SRMs): SRM 3258 Bitter Orange Fruit; SRM 3259 Bitter Orange Extract and SRM 3260 Bitter Orange Solid Oral Dosage Form. The limit of quantitation (LOQ) for all alkaloids is approximately 1 pg on-column, except for octopamine (18 pg on-column). Additionally, the method has a linear dynamic range of = 3 orders of magnitude for all of the alkaloids. Individual, as well as total , alkaloid levels (mg/kg) in the NIST SRMs were determined and compared to the levels measured by an independent liquid chromatography/fluorescence detection (LC/FD) method. Good concordance between the LC/MS/MS and LC/FD alkaloid measurements was demonstrated. LC/MS/MS analysis of the alkaloids in the SRMs resulted in mean measurement imprecision levels of = 10% relative standard deviation (RSD).
Journal of Agricultural and Food Chemistry


bitter orange alkaloids, dietary supplements, hordenine, liquid chromatography, n-methyltyramine, octopamine, synephrine, tandem mass spectrometry, tyramine


Nelson, B. , Putzbach, K. , Sharpless, K. and Sander, L. (2007), Mass Spectrometric Determination of the Predominant Adrenergic Alkaloids in Bitter Orange (Citrus aurantium), Journal of Agricultural and Food Chemistry (Accessed May 23, 2024)


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Created April 23, 2007, Updated October 12, 2021