Characterization and Quantitation of Yohimbine and Analogues in Botanicals and Dietary Supplements by LC/MS

Extracts of the bark of the Pausinystalia yohimbe tree (Family, Rubiaceae) are considered to enhance both athletic and sexual performance. Yohimbe bark can contain between 1% to 8% alkaloids or more, the primary being yohimbine, and its extract is sold as an ingredient in dietary supplements and advertised to have homeopathic properties in addition to performance enhancement. The compound yohimbine HCl has been banned in Australia and considered a drug in the United States and has been associated with adverse health effects and even death. The US FDA (21CFR310.528) states that any claim of sexual enhancement qualifies the ingredients, including yohimbine and yohimbine HCl, as a drug and is treated accordingly. Further, when used as a legal dietary supplement, the yohimbine must originate from inclusion of the bark or extract. Addition of synthetic yohimbine HCl violates the cGMPs for dietary supplements (21CFR 111). These regulations require good analytical methods to both chemically characterize the bark extract and quantify yohimbine and its analogues. Sample preparation using a QuEChERS based approach was followed by characterization of samples using accurate mass LC/QTOF MS along with quantitative analysis by triple quadrupole LC/MS. Excellent sensitivity was achieved by LC-QQQ (LOQ =< 0.1 ng/mL) while high resolution MS allowed for identification of yohimbine isomers and analogues. Greater than expected amounts of yohimbine are found in some supplements while others show undeclared alkaloids and evidence of synthetic adulteration with exogenous yohimbine.