The study demonstrates the applicability of laser ionization time-of-flight mass spectrometry for real-time measurement of polychlorinated biphenyls (PCBs). Picosecond 266-nm laser light ionization reduced fragmentation and provided very high PCB detection sensitivity. This high sensitivity has advantages in terms of real-time monitoring capability as compared to the conventional GC-ECD or GC-MS methods, which require at least several days for the analysis of PCBs. Detection sensitivity of under 0.01 mg/Nm3 was achieved with a 1-min measuring time; this sensitivity is superior to the exhaust gas control guideline of 0.15 mg/Nm3 by a factor of 10. A prototype PCB monitoring device has been developed and tested in a pilot PCB treatment plant. The 1-min detection time represents a substantial advance in the monitoring of exhaust gas and the workplace atmosphere in accordance with safety regulations.
The emissions of organic hazards from environmental protection equipments and other facilities have become a major social issue, and the evaluation of toxicity concentration requires methods having both high precision and high chemical selectivity. LI-IT-TOFMS (laser ionization/ion trap storage/time of flight mass spectrometry) is expected to be a powerful tool for environmental monitoring. This report, discusses real-time LI-IT-TOFMS measurements gaseous 2 4 chlorinated PCBs in order to evaluate the applicability of the environmental monitoring method. With respect to the effect of ion trap storage for PCBs, we found that it was due to the driving RF voltage on the ring electrode in the ion trap. For the ions of PCBs produced by laser irradiation, we observed that it was more efficient to reach the center of the ion trap by using a gated RF voltage rather than by using a continuous RF voltage. We simulated the ion trajectories in the ion trap by using SIMION 7.0. We found that the voltage of the exit end cap electrode affected both the number of ions trapped and the orbit of ions inside of the trap cell. Optimization of this parameter was performed using both simulated and experimental results. The achievable PCB sensitivity for real-time (1 minute) measurements using the LI-IT-TOFMS technique was found to be in the pptV range ( 0.01 mg/Nm3) by a comparison with the conventional gas sampling GC/MS method. A satisfactory proportional relationship was confirmed between laser-based and conventional results. In the future we will pursue the method for environmental monitoring.
As an initial step in clarifying the mechanisms of the combustion and gasification of biomass, fundamental experiments on the thermal decomposition and numerical simulation for the elementary reaction of decomposed chemical species have been performed. In the experiment, various kinds of biomass particles were rapidly heated by applying an electrically induced magnetic field to the metal tray on which the object particles had been placed. It was clarified that for the two decomposition temperatures of 590 and 1040 °C investigated, the relationship between decomposition rate and heating time was the same, but that the components of the decomposed species were substantially different; the mole fraction of C6-C9 components for the low temperature of 590 °C was 3 to 10 times greater than that corresponding to 1040 °C. Furthermore, a close relationship was ascertained between the percentage of heavy species (C10-C20) and the amount of lignin contained in the biomass. Numerical simulation indicated that these heavy species could decompose to C1 and H 2 at over 1000 °C with H 2 O acting as the oxidation agent, and that the effect of H 2 O under atmospheric pressure reaches a maximum at P H2O -0.7 atm.
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