title: Evaluation of the gravimetric tetraphenylarsonium method for the determination of Tc(VII).
abstract: Solubility losses in the gravimetric tetraphenylarsonium method for determining pertechnetate have been evaluated. Liquid scintillation counting was used to measure the beta(-) activity of (99)Tc in the filtrate, and indicated solubility losses of about 1% in analyses yielding 40-50 mg of precipitate. The solubility product Of (C(6)H(5))(4)AsTcO(4) is estimated to be (8.6 +/- 0.2) x 10(-10) at room temperature (24-25 degrees ) and K(sp) for (C(6)H(5))(4)AsReO(4) at approximately 21-23 degrees is estimated at (2.6 +/- 0.3) x 10(-9). Both values are satisfactory for gravimetric purposes, but to keep solubility losses within 1% at least 40mg of (C(6)H(5))(4)AsTcO(4) or 80 mg of (C(6)H(5))(4)AsReO(4) should be obtained (assuming 20 ml of solution, 20-30% excess of precipitant and 6 or 7 washes with 5-ml portions of distilled water).
authors.affiliation: Department of Chemistry, Indiana University-Purdue University, Fort Wayne Campus, Fort Wayne, Indiana 46805, U.S.A.
authors.forename: R A
authors.initials: RA
authors.lastname: Pacer