A review of methods for the simultaneous detection of illegal ingredients in food supplements

Food supplements are at risk from contamination with illegal ingredients on a global scale. To date, the official food control laboratory system in the UK does not appear to have been particularly active in the analytical control of illegal ingredients in food supplements. From a survey of notifications (2009 to 2016) to the European Union rapid alert system for food and feed (RASFF) food supplements are shown to be adulterated with a complex range of compounds and substances. These include permitted food additives in excess of their limits, contaminants, unauthorised novel food ingredients, unauthorised nutritionally-related compounds, excess vitamins, controlled drugs, and one instance of the poison strychnine. However, arguably, the most important factors that jeopardise the safety of food supplements are their adulteration with synthetic pharmaceutical drugs. In order to assist official control and trade analysts to regulate the safety of food supplements with regard to the presence of illicit pharmacologically active ingredients or contaminants the RASFF database, 2009 to 2016, was surveyed for such compounds. The most frequently notified were sildenafil and its analogues, sibutramine and derivatives, 1,3-dimethylamylamine (DMAA), yohimbine and tadalafil. Their toxicology and methods for their detection and determination have been reviewed in this paper. Method details are tabulated with references and general conditions have been suggested for a first choice liquid chromatography-mass spectrometry (LC-MS) screening method for the compounds sildenafil, tadalafil, vardenafil and yohimbine. If high field NMR is available this would appear to be an excellent first-line method of control for herbal food supplements. It would be helpful that when the suggested method(s) are assessed and validated in Association of Public Analyst member laboratories against a matrix of food supplements incurred or spiked with the target illegal ingredients that the data be reported herein