Determination of Chlorobiphenyl in Rat Adipose Tissue by Neutron Activation Analysis

Abstract

A method for the determination of chlorobiphenyl in rat adipose tissue by neutron activation analysis is described.
Adipose tissue from the tritiated chlorobiphenyl loaded rat was extracted with nhexane, and the extrat was partially purified by thin layer chromatography. Both crude and partially purified extract were used for analysis. The extracted material was sealded in a quartz ampoule while cooling with dry ice, and activated in a research reactor, Model TRIGA-II, at 4.4×10¹² n/cm²⋅sec for 30 minutes. After cooling, ampoule was cleaned with diluted nitric acid, distilled water and acetone, and heated in electric furnace at 650°C for 10 minutes for pyrolysis of extract. Ampoule was then broken in 5%NaOHand H₂O₂solution (30: 1/ν: ν) containingNH₄Clas a chlorine carrier to recover³⁸Clin solution. To eliminate²⁴Nacontamination chlorine was precipitated asAgCIand the precipitate was washed withHNO₃and distilled water followed by redissolving in ammonium solution. Precipitating and washing were repeated again to get the final precipitate for assay of radioactivity. The radioactivity was measured with³⁸Clγ-ray spectrum and its half life of 37.5 minutes. The sensitivity of the method was 0.1 micro gram.
The value of chlorobiphenyl in adipose tissue was calculated assuming that it exists in fat without any changes in structure. At the same time, a method of measuring tritium labelled chlorobiphenyl with a liquid scintillation counter was carried out and a comparative study of both measured values made.
The validity of values obtained by this assay procedure was confirmed by the demonstration that the value agreed with those determined independently by the analysis based on the amount of tritium activity in the extracted material.