The Environmental Chemistry Department run tests on samples to detect presence of heavy metals. The samples are received from a variety of sources like WIPP, NMSU, Carlsbad Cummunity Gardens, local communities from Carlsbad and Las Cruces. The air filter samples received from WIPP them are commonly referred to as a fixed air sampler or FAS. Elemental analyses are conducted on weekly composites of these filters.
Individual FAS filters are digested using a mixture of strong acids in a microwave digestion unit, and weekly composites are prepared from the digestates of the individual filters. The composites are then analyzed for a suite of trace elements with the use of a Perkin-Elmer (Model Elan 6100), Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The ICP-MS methods can provide data for up to ~35 elements, but in practice the concentrations of some elements, including As, Be, Cd, Er, Eu, Sc, Se, Sm, Tl and V are often below detectable or quantifiable levels, and a second set of elements (notably Ag, Li, and Sn) have variable concentrations in blank filters which makes their quantification difficult.