Analysis of coumarin in various foods using liquid chromatography with tandem mass spectrometric detection

Recently authorities and the media have published reports of increased coumarin levels in Christmas biscuits, gingerbread, cinnamon cookies and other foods. The maximum tolerance limits for coumarin in food are set out in EC Directive 88/388/ECC. Since the standard use of analytical techniques, such as HPLC-UV, are only limitedly suitable for verifying compliance with the regulatory limit of 2 mg/kg for coumarin in food, a selective, sensitive isotope dilution LC-MS/MS method for determining coumarin content in foods was developed, tested and validated, and the results then compared to the HPLC-UV method. This LC-MS/MS method increased selectivity and raised sensitivity by a factor of 100 compared to the HPLC-UV technique. The respective limits of determination and quantification for the method were 0.03 and 0.05 mg/kg, respectively, with an RSD of 1-8% and a linearity range of 0.1-500 ng/mL (corresponding to 0.05-250 mg/kg in food). In addition, a selection of around 500 food samples was also tested for coumarin content using the LC-MS/MS technique.