Development of a Stationary Phase Optimised Selectivity Liquid Chromatography based screening method for adulterations of food supplements for the treatment of pain.

Illegally adulterated dietary supplements are an increasing problem worldwide. One of the important groups of often adulterated products are the dietary supplements, sold for the treatment of pain. These often contain analgesics, a heterogeneous group of molecules, containing both hydrophilic and hydrophobic compounds. The development of a screening method for these components, especially when mass spectrometric detection is not available, necessitates chromatographic separation, difficult to achieve with traditional chromatographic columns. In this paper Stationary Phase Optimised Selectivity Liquid Chromatography was used for the development of a screening method for nine analgesics, codeine and caffeine, often present in this type of dietary supplements. The method shows a good separation of all the compounds, allowing the screening to be performed with diode array detection and is fully compatible with mass spectrometry. The method was validated for its selectivity following the guidelines as described for the screening of pesticide residues and residues of veterinary medicines in food.