Fast-neutron activation analysis of silicon in sputum

Abstract

A method for a relatively rapid and accurate determination of silicon in sputum by activation analysis is described. The method has been developed to identify and separate the cases of silicosis from those of pulmonary tuberculosis.

The sputum is digested by trypsin, then spun in a centrifuge three times at room temperature, and once after heating with 5 per cent. trichloroacetic acid to remove phosphorus which interferes in the activity measurement. For irradiation, a neutron generator with a fast-neutron yield of 2 × 10⁹ n per cm² per second is used. After exposing for 2·3 minutes and then waiting for 1 minute the activity measurements are made by using a multi-channel analyser for 4·6 minutes. The silicon content is evaluated from the aluminium-28 activity produced by the reaction ²⁸Si (n,p)²⁸Al with a photopeak at 1·78 MeV.

The results show that the silicon content in the sputum of patients suffering from silicosis is, on the average, four times that of the samples used for reference.