Particle size and composition are the two most fundamental properties of atmospheric aerosols. The BNL Single Particle Laser Ablation Time-of-flight Mass Spectrometer (SPLAT-MS) was designed to characterize the size and composition of individual particles as small as 50nm in real-time at a rate of 20 particles per-second. For SPLAT-MS the TX 2000 Air Quality Study in Houston, TX was its maiden voyage when it was deployed for 3 weeks on a tall building (300m) west of the Houston city center.

About 240,000 particles were detected, sized and their composition characterized. A preliminary analysis of the data shows that the over 50% of the particles contain organics and more than 40% contain sulfates virtually all of which were found to be internally mixed with organics. Many particle types were detected episodically for a few hours before they disappeared for a few days. We present an analysis of an episode that took place on the night of the 13th of September when the site was above the nocturnal boundary layer engulfed by a power plant plume. During this night the number of nitrate and vanadium particles suddenly increased for a few hours.

The recently developed data analysis and visualization tools will be applied to the single particle data set and the analysis results will be presented in the context of the overall TX 2000 field campaign.