Clinical Chemistry, Vol 21, 1212-1216, Copyright © 1975 by the American Association for Clinical Chemistry

Continuous Monitoring of Radioactivity of Effluent from a High-Speed Amino Acid Analyzer, with a New System of Sample Segmentation

¹ Department of Pediatrics, University of California at San Diego, La Jolla, Calif. 92037.

Radioactivity in the effluents from high-speed liquid chromatographic analyzers was continuously measured by use of a new sample segmentation system. To achieve highest counting efficiency, the column effluents were mixed with scintillation fluid carrying small segments of semisolid, resilient spacer. After passing through a mixer, the mixture was passed through a hollow-tube flow cell mounted in a liquid scintillation spectrometer. Because the added spacer acts like a continuous series of pistons, it unifies flow rate at center and walls of the conduit and so decreases sample carryover. This system was applied to measurement of radioactivity in the effluent of a high-speed amino acid analyzer, in which some amino acids emerge at 30-s intervals. The resulting profiles were as well resolved as were the ninhydrin-color profiles. Counting efficiencies for tritium and carbon-14 were comparable to those obtained by static counting in vials.

Submitted on March 20, 1975
Accepted on June 4, 1975