A simple method for the quantitative determination of tellurite ions i
n aqueous media including blood plasma or serum is described. This ass
ay is based on the selective and potent inhibition of a Zn2+-glyceroph
osphocholine phosphocholine phosphodiesterase by tellurite ions in the
presence of tetramethylammonium ions. The assay method, which showed
a good relationship between the enzyme inhibition and the amount of te
llurite ions (50 nM-5 mu M), was found to be rapid (< 5 min), reproduc
ible (mean C.V., 6.5%), and at the same time, sensitive, showing a low
limit of detection (50 nmol). Based on this technique, the removal of
tellurites by thiols, and the kinetics for the uptake of tellurite io
ns in blood were investigated.