Quantitation of images from a multiwire camera for autoradiography of tritium-labelled substances

We have shown that tritium-labelled substances in two-dimensional systems can be quantitated using a multiwire camera. Its accuracy has now been improved by correcting results for non-uniformity of response over the detection area. Uniformity was assessed by imaging plates of nominally uniform activity. The results were then used to correct images from plates containing tritium-labelled proteins using a computer program. Errors were reduced from 11.3 (+/- 6.1) to 7.7 (+/- 2.8)% for standard sources and from 6.2 (+/- 1.8) to 1.9 (+/- 0.6)% for a plate containing the labelled proteins. The conducting carbon layer covering the plate absorbed 36 (+/- 3)% of the tritium beta radiation and was estimated to be 85 nm in thickness. Quantitation of the labelled proteins by the camera gave a good correlation with protein content (chi-squared: 30-40%). The activities of the protein samples were measured to an accuracy of 10% by comparison with standard sources. These results indicate useful quantitation of tritiated compounds in two-dimensional media using the multiwire camera.