Root cadmium desorption methods and their evaluation with compartmental modeling.

• Desorption of plant roots is often employed in studies of plant physiology and nutrition; however, there have been few studies on the validity of desorption procedures. • Branched and in-line kinetic models with five compartments - cadmium (Cd)-chelate, Cd(2+), root apoplast, root symplast and vacuole - were developed to evaluate the efficacy of diethylenetriaminepentaacetic acid (DTPA) and CaCl(2) methods for the desorption of Cd from roots of durum wheat seedlings. Solution Cd(2+) could exchange with apoplast and symplast Cd simultaneously in the branched model and sequentially in the in-line model.

Analytical variables affecting exchangeable copper determination in blood plasma.

To resolve discrepancies observed in the determination of plasma exchangeable Cu (also called direct reacting Cu or loosely bound Cu) by several methods, plasma storage techniques and various aspects of a stable isotope dilution procedure for exchangeable Cu were evaluated. Results indicated that the exchangeable Cu fraction of plasma increased with storage at room temperature, at 5 degrees C and when subjected to repeated freeze/thaw cycles. Samples could be safely stored at -65 degrees C.