SELECTIVE DETECTION OF PHENOL IMPURITIES IN WATER

CO2 laser ablation of the frozen water matrix, followed by resonance-enhanced multiphoton ionization technique coupled with reflection time-of-flight mass spectrometry, has been used for analysis of water polluted with phenol molecules. The linear dependence of the ion signal on the phenol concentration ranged from 0.1 mu g L(-1) to 10 mg L(-1) under identical experimental conditions. A detection limit of 0.1 pg L(-1) was achieved for phenol. It was shown that the overall sensitivity of 1 ng L(-1) (1 ppt) can be attained with the present experimental setup, The velocity distribution of the ablated phenol species was approximated by a Maxwell-like function at a temperature of 150 K, Contours of the S-0-S-1 (36352 cm(-1)) electronic transition of both thermally evaporated and CO2 laser-ablated phenol molecules have been obtained, Their comparison demonstrated that the rotational temperature, in the case of laser ablation of frozen water matrix, appeared to be lower than 140 K. It is believed that the cooling effect is due to jetlike expansion of water molecules into vacuum. A potential benefit of this phenomenon for spectroscopic and mass spectrometric studies of complex nonvolatile and thermally labile molecules is discussed.