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A quick and sensitive reversed-phase high-performance liquid chromatography (HPLC) method has been developed in order to determine the concentration of Propofol (2,6 diisopropylphenol) in human serum. Propofol can be isolated from serum by adding 0.5 mL precipitating solution. This consists of an acetonitrile and perchloric acid (67:33, v/v) mixture, which also contains dibutylphthalate (2 mg/100 mL) as internal standard. The sample is then mixed for 1 min on a vortex-mixer. The endogenous serum substances precipitated by acetonitrile and perchloric acid are further separated by centrifugation. The supernatant is directly injected into the HPLC system. A 250- x 4.6-mm column, packed with 10-microns Spherisorb reversed-phase octadecylsilane particles (C18), is used for chromatographic separation. The mobile phase consists of an acetonitrile-water mixture (67:33 ratio) with 0.4 mL acetic acid (pH 4). Propofol is monitored by a UV-visible detector at 270 nm and 0.1-0.002 absorbance units full scale (AUFS). The detection limit of Propofol (in human serum) is 0.1 mg/L for a 20-microL injection volume. The time of the assay is less than 20 min, including sample preparation.

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The observation of photocontact dermatitis from Heracleum mantegazzianum Sommier et Levier in 2 gardeners at work prompted the analysis of furocoumarin content of stem, leaves and fruits of the plant during a period of 1 year. Their concentration was found to be maximal in fruit, intermediate in leaf, and minimal in stem. Psoralen was the most prevalent substance in the leaf and bergapten in the fruit. In the stem, in contrast, individual furocoumarins were found in lower but variable concentrations. 3 furocoumarin seasonal peaks were observed in the leaf: the maximal peak occurred in June, the intermediate in August, the minimal in November. This trend corresponds to 3 biological phases of the weed.