PAST, PRESENT, AND FUTURE APPROACHES FOR TESTING METALS FOR ENVIRONMENTAL CONCERNS AND REGULATORY APPROACHES

Procedural approaches used for sample preparation have remained relati vely unchanged in recent years except for a trend toward extracting or digesting larger numbers of samples and the possible use of microwave digestion. The use of sequential extraction schemes for metals and me talloids has increased as a result of a growing interest in in suti re mediation of contaminated soils. Here questions focus on how soil amen dments or treatments have rendered metals or metalloids less reactive or bioavallable. The use of computers for control of instruments, samp le presentation, and interference correction represent significant adv ancements for many of the routine analytical instruments in use today. The development of inductively coupled plasma-mass spectrometry (ICP- MS) allows for much lower detection limits for certain elements and th e possibility of performing isotope ratio analysis. Synchrotron radiat ion-based techniques have become more common in recent years and offer nondestructive methods for examining metal and metalloid speciation i n environmental media, Applications for the complex mixtures found in natural samples are developing. Bioavailability measurements are also becoming more important in light of trends in soil remediation. Feedin g studies and invitro bioaccessibility studies can be used to estimate bioavailability or bioaccessibility for elements such as arsenic (As) and lead (Pb) and the results can be used for determining remediation strategies for sites with contaminated soils.