MEASUREMENTS COMPARISON OF OXYGENATED VOLATILE ORGANIC-COMPOUNDS AT ARURAL SITE DURING THE 1995 SOS NASHVILLE INTENSIVE

Simultaneous measurements of oxygenated volatile organic compounds (OV OCs) by four independent research groups at the Youth Incorporated (YI ) site during the 1995 Southern Oxidants Study Nashville Intensive, be tween July 4 and 30, 1995, provided a unique opportunity to compare re sults from different techniques. 2,4-Dinitrophenylhydrazine (DNPH) coa ted C18 (C18(AtmAA)) and Si-Gel (Si-Gel(MTE)) cartridges were compared with each other and with two sorbent-based preconcentration gas chrom atographic (GC) techniques coupled with mass spectrometric (MS) detect ion (GC/MSUM and GC/MSPU) or flame ionization detection GC/FIDUM. The experiment consisted of both a laboratory (part A) and an ambient air comparison (part B). In part A of the study, standard mixtures of OVOC s were diluted in a flowing gas stream of humidified, purified air, bo th with and without addition of O3, and distributed to participant's i nstrumentation. Concentrations were compared with the expected values based on known cylinder concentrations and dilution factors. In part B of the study, the instruments sampled ambient air from a common glass manifold. Species intercompared were formaldehyde, acetaldehyde, acet one, and propanal. The C18(AtmAA) data were typically higher than the Si-GelMTE data for the four intercompared compounds, and possible expl anations are given. Agreement between the cartridge systems and the GC /MS, GC/FID systems for comeasured compounds was poorer than expected but improved towards the end of the experiment. The GC/MS systems trac ked each other well for acetone, but there were differences in the abs olute concentration values. These results show that improvements in th e accuracy and comparability of techniques should be of high priority.