RADIOMETRIC DETERMINATION OF TRACE AMOUNTS OF ZINC USING LIQUID SCINTILLATION-COUNTING

A sensitive and selective radiometric method of substoichiometric isot ope dilution analysis for the determination of trace amounts of zinc i s described. The activity of Zn-65 used as a tracer in this method was measured by liquid scintillation counting and its counting efficiency was found to be 76 +/- 2.7%. The method is based on the extraction of the ion-association complex of zinc from thiocyanate medium at pH 7.9 using substoichiometric amount of Aliquat-336 in toluene. The method is sensitive to 20 ng of Zn(II) in an aqueous phase volume of up to 15 ml and its reliability was tested by applying it to a certified refer ence material-magnesium alloy and pharmaceutical samples. (C) 1998 Els evier Science B.V. All rights reserved.