Different sample preparation methods combined with LC-MS/MS and LC-UV for determination of some furocoumarin compounds in products containing citruses

Furocoumarins are a group of naturally occurring oxygen heterocyclic compounds synthesized by different plants (mainly Citrus species). They have several physiological effects, e.g. photoreactivity and inhibition of intestinal and liver drug metabolism, which imply the need to control their concentration in products intended for human use. We tested different sample preparation approaches and LC with different detection modes: UV, APCI-MS/MS and ESI-MS/MS for the determination of bergapten (BGPT) and bergamottin (BGMT) in different samples of beverages and cosmetics. Direct injection of sample solutions was applicable only for essential oils, while liquid-liquid extraction proved to be time-consuming and unsuitable for our samples. Solid-phase extraction with a preconcentration factor of 20 yielded repeatable recoveries for aqueous solutions (97.4% for BGPT, 64.6% for BGMT) and the concentration range was > 0.1 mg/l for UV detection and 2-1000 mu g/l for MS/MS detection. Results of sample analysis indicated some problems connected both to detection and the extraction. The standard addition method for quantification yielded the most reliable results. Copyright (C) 2008 John Wiley & Sons, Ltd.