A clean laboratory for ultralow concentration heavy metal analysis

Summary

Laboratory facilities and methods are described which have been developed in our laboratory in collaboration with C. Patterson's group at the California Institute of Technology for the reliable measurement of various heavy metals at extremely low concentration levels down to the sub pg/g level in Antarctic and Greenland snow and ice. All analytical work is performed inside a clean laboratory pressurized with air filtered through high efficiency particle air filters and equipped with all-plastic laminar flow clean benches. High-purity water is produced by ion-exchange resins, and high purity acids from the US National Institute of Science and Technology are used. The various containers which are in contact with the samples are made of conventional low density polyethylene and FEP teflon. These containers are cleaned by immersion during several weeks in a succession of heated acid baths of increasing purity. Extremely careful blank determinations are made in order to quantitatively determine how much of the investigated metals is added to the samples from each separate reagent, from the walls of the various containers and from the air of the clean laboratory.