SELECTIVE DETECTION OF PHENOL IMPURITIES IN WATER

CO2 laser ablation of the frozen water matrix, followed by resonance-e nhanced multiphoton ionization technique coupled with reflection time- of-flight mass spectrometry, has been used for analysis of water pollu ted 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) und er identical experimental conditions. A detection limit of 0.1 pg L(-1 ) was achieved for phenol. It was shown that the overall sensitivity o f 1 ng L(-1) (1 ppt) can be attained with the present experimental set up, The velocity distribution of the ablated phenol species was approx imated 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 th an 140 K. It is believed that the cooling effect is due to jetlike exp ansion of water molecules into vacuum. A potential benefit of this phe nomenon for spectroscopic and mass spectrometric studies of complex no nvolatile and thermally labile molecules is discussed.