QUANTITATIVE-DETERMINATION OF PHOTOTOXIC FUROCOUMARINS IN CELERIAC (APIUM-GRAVEOLENS L. VAR. RAPECEUM) USING SUPERCRITICAL-FLUID EXTRACTIONAND HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Linear phototoxic furocoumarins were determined in fresh celeriacs usi ng supercritical fluid extraction (SFE) and reversed phase liquid chro matography. The SFE method was optimized by comparing extraction yield s at different temperatures and pressures, resulting in the density of the carbon dioxide between 0.3 and 0.9 g/mL. The addition of a drying agent (sodium sulphate) to the sample was important in avoiding the p lugging of the linear restrictor used. The optimum yields of furocouma rins were obtained when the density of the carbon dioxide was 0.58 g/m L. The repeatability was enhanced by careful selection of the collecti on solvent; however, between the solvents tested, only small differenc es in their efficiency to retain the analytes were observed. The deter mination of furocoumarins from fresh material was more efficient, and difficulties were observed in the isolation of the analytes from freez e-dried or air-dried ground celeriac. The amounts of furocoumarins var ied within the batches of tubers, the sum of three phototoxic furocoum arins being 2.1-4.5 mg/kg (on a fresh weight basis). However, the yiel ds obtained by SFE were in agreement with those from Soxhlet extractio n. (C) 1997 by John Wiley & Sons, Ltd.