THALLIUM DETERMINATION IN BIOLOGICAL-MATERIALS BY RADIOCHEMICAL NEUTRON-ACTIVATION ANALYSIS

The determination of thallium in biological materials sometimes cause problems because of the low concentrations of this toxic element. In the present work a method is described which optimizes the parameters affecting the specificity and sensitivity of the radiochemical NAA of thallium in biological samples. High thermal neutron flux, complete decomposition of the organic matter by pressurized digestion, T1I precipitations, liquid extraction of HT1Br4 and La(OH)3 scavenging purification are the steps leading to the final homogeneous preparation of Tl2CRO4 for beta-activity measurement. The method was applied to various materials as bovine liver, bone and nails. Good agreement was found between certified and determined thallium concentrations of the reference material CRM 176. The chemical yield comes to about 80%, with low deviations. The sensitivity of the method is about 10(-3) mu-g/g, the standard deviations being in the range of 3.6% (CRM 176), 14% (bovine liver), and 17% (bone). Detailed working instructions are given.