Statistical Analysis of online VOC measurements obtained by Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) during the TEXAQS2000 intensive period will be presented. This relatively new technique, which has been successfully used in various other field campaigns, such as LBA-CLAIRE, INDOEX and SOS, was based at the La Porte site and deployed for continuous long-term monitoring. Several multivariate techniques including the recently developed Multilinear Engine (Paatero et al., 1999) helped to identify various Ship Channel sources and distinguish between different anthropogenic emissions. An assessment of the selectivity and an interpretation of mass scans of this online technique in a complex urban and industrial VOC matrix will be given.