Determination of Carotenoids in the Chinese Medical Herb Jiao-Gu-Lan (Gynostemma Pentaphyllum MAKINO) by Liquid Chromatography

A QSTAR Pulsar quadrupole time-of-flight mass spectrometer was used for the determination of chlorophenols in surface water samples. The investigated compounds were: 2-chlorophenol; 4-chloro-3-methylphenol; 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol. Each analyte is listed by the US-EPA as a priority pollutant. Sample enrichment of water samples was achieved by a solid-phase extraction procedure, using a Waters Oasis HLB cartridges followed by LC-Tandem-MS. A narrow-bore 2.1-mm-i.d. reversed phase LC C-18 column operating with a mobile phase flow rate of 0.2 mL min^–1. was used to separate the analytes. The whole column effluent was diverted to the ion spray interface source. For the determination of the analytes the hybrid quadrupole time-of-flight spectrometer operated in product ion scan acquisition mode. Average recoveries from 2 L samples varied from 91 to 110% and relative standard deviations (RSD) were less than 10% for all samples. The limit of detection (signal-to-noise ratio=3) of the method for the phenols in drinking water samples is less than 10 ng L^–1. In real environmental samples, levels of the selected analytes varied from non-detected up to 0.5 g L^–1 for pentachlorophenol.