Determination of trace environmental pollutants in a single microparticle by laser ionization/ion trap mass spectrometry

Analysis of environmental samples by using mass spectrometry has been investigated by many researchers for last couple of decades. Ion trap mass spectrometry (ITMS) is a newest member of the mass spectroscopic techniques in this field of applications. In this report laser ionization ITMS on PAHs and DDT are discussed. Laser ionization is necessary when a single particle is to be analyzed by ITMS. The third harmonic of Nd:YAG laser (355 nm) as well as output from the XeCl excimer laser are used as an ionization source of the particles. Samples are dissolved in solvent and mixed with SiC micro-particles which has size distribution of 10-50 microns. Samples are prepared by heating the mixed samples to dry solvents. A special sample introduction system was developed in the present study by modifying solenoid valve. The operation of the solenoid valve was synchronized with laser pulses to timely hit the particle to ionize. The master trigger was generated from the scattered signal of the sample particle that are detected by photomultiplier tube.