Carrier Iodide Research Articles

The determination of iodide‐iodate activity in sodium radio‐iodide (I131) by automatic scanning of paper chromatograms

Rf values of different width filter paper chromatograms using 75 per cent methanol in an ascending system are presented for iodide and iodate. The chemical identity of the spots is determined by the use of carrier iodide and iodate. The iodide spot was developed by spraying the dry chromatogram with starch hydrogen peroxide solution. The iodate spot was developed with a spray of ascorbic acid‐starch solution. Description of the equipment is given. The relationship of the chart drive speed and the optimal slit width to the time constant of the counting rate meter is discussed and the minimal slit width calculated for the instrument used. Integration of the curves gave areas representing the total activity at each spot. The ratio of the iodide‐iodate activities thus determined differed from the relative readings of the counting rate meter.

Thyroidal iodide trapping as influenced by serum iodide levels and thyrotrophin.

IT IS well established that the thyroid possesses a mechanism whereby it concentrates (“traps”) inorganic iodide (VanderLaan and VanderLaan, 1947; Taurog et al., 1947). Studies using tracer doses of radioactive iodine have disclosed the thyroid: serum iodide gradient to be profoundly influenced by thyrotrophin (TSH) (VanderLaan and VanderLaan, 1947; Vander- Laan and Greer, 1950; Ingbar and Roberts, 1952; Halmi et al., 1953). Up to 100 jug of stable iodide carrier added to the tracer had no appreciable effect on the thyroid: serum radioiodide concentration ratio (T/S) of normal (VanderLaan and VanderLaan, 1947) or of goitrous rats (Vander- Laan and VanderLaan, 1947; Taurog xyiet al., 1947). However, further increase of the dose of stable iodide caused the T/S of propylthiouracil (PTU)-treated rats to drop (VanderLaan and VanderLaan, 1947; Wyngaarden et al., 1953). This suggested to Raben and Astwood (1949) that the capacity of the thyroid for iodide is limited, and indeed