This poster presents on-going work in the project, ñDiscovery of Xenobiotics Associated with Preterm Birthî. The technique for discovery is mass spectrometry, and both biological and environmental samples are being tested. æNew analytical methodology is being developed and applied, especially in collaboration with the four other RO1 Projects in the P42 project, ñPuerto Rico Test site for Exploring Contamination Threats (PROTECT). PROTECT focuses on pregnant women in Puerto Rico since this island has a very high (19%) incidence of preterm birth, a 35% increase since 1981. æPreterm birth also is elevated throughout the United States, after undergoing an increase of 12% during the same period of time. It is assumed in this project that exposure of pregnant women to environmental chemicals during pregnancy has contributed to the increase in incidence of preterm birth, a $26 billion, year burden on our society. The four chapters of this poster, each presenting a different area of our work on nontargeted chemical analysis, are as follows. Chapter 1. Solid phase extraction of large pregnancy urine samples is being conducted with a stirring tea bag. æChapter 2. Environmental chemicals might contribute to preterm birth via damage to DNA in the placenta. ææChapter 3. A æMALDI-TOF/TOF-MS assay has been setup for measuring phthalates, and also general organic chemical contaminants, in ground and tap water samples. Chapter 4. æDerivatization can help to deal with sample complexity for nontargeted chemical analysis, mainly by selecting a given classes of chemicals for enhanced detection.