Trace Elements Analysis Core: Abstract The primary goal of the Trace Element Analysis (TEA) core is to provide low level trace element analysis and speciation and analytical chemistry expertise to Dartmouth SRP researchers to allow them to successfully complete the aims of their individual projects. Additionally, the TEA core strives to be at the forefront of (mission-related) method development that augments the themes of the Dartmouth SRP projects and advances these projects by providing analytical advances such as lower detection limits, quantification of as yet unmeasured metal species, and the novel application of an analytical methodology. The TEA core utilizes state of the art analytical instrumentation based on inductively coupled plasma mass spectrometry (ICP-MS) to provide low level determinations of trace elements in a variety of biological and environmental matrices. The TEA core also provides speciation analysis for arsenic and mercury by liquid chromatography and gas chromatography coupled to ICP-MS, respectively. The core strives to provide accurate, precise and validated data to support Dartmouth Superfund Projects and employs a quality control program commensurate with that expected of US EPA contract laboratories. The TEA core participates in national and international proficiency testing to ensure the accuracy of its analytical procedures and has been subject to both internal and external review processes to ensure it is providing useful analytical services in a timely manner. The core develops analytical methods such as 2D elemental imaging of biological samples by laser ablation-ICP-MS or extraction and determination of arsenic species in foods and juices to support projects 1 and 4. The core serves project 2 by providing new instrumentation and expertise for ultra-low level mercury determination and speciation. The core also serves project 3 and 4 by the determination of arsenic concentration and speciation in water, biological tissues and cell suspensions and lysates.