Anomalous binding of organic contaminants may be artifactual due to radiochemical impurities

A potential artifact is described that could lead to erroneous estimates of the partition coefficients for binding of contaminants to sorbents such as soil, sediment, or dissolved humic material. The artifact can arise if sorbents are radiolabeled but contain even relatively small amounts of radiolabeled impurities. The following types of errors could result from data affected by this artifact: partition coefficients for sorption could be underestimated; systems in which binding was fully reversible could appear to be at least partially nonreversible and partition coefficients could appear to decrease as the sorbent concentration increased. Several criteria are suggested to assure that experimental results are not affected by this artifact. (author)