Patent GB-1103995-A (GB)
Title: Activation analysis
Inventor: COMAR DOMINIQUE
IPC: G01N23/222
Filed: 1966-04-15
Abstract: 1,103,995. Determination of halogen. COMMISSARIAT AL'ENERGIE ATOMIQUE. 15 April, 1966 [22 April, 1965], No. 16658/66. Heading B1X. [Also in Division G1] In the determination of the concentration of a halogen element in a sample by activation analysis, the element is activated by neutron irradiation of the sample, diluted with an amount of its inactive isotope, and isolated in purified solution form, and its activity is evaluated by measurement while the sample is stored in a measuring loop. The determination of the iodine content of blood serum is carried out using five samples of serum. one of which acts as a reference and already contains a known measure of radioactive iodine (I-128). The samples are first irradiated for 30 minutes by thermal neutrons and then poured into respective flasks 11 in a turntable 12. A nozzle 14 dips into the first flask 11 and a pump 20 is switched on by means of the programme unit C which controlls the whole process. The sample is sucked from the flask 11 and passes through the pump 20 where it is segmented with air and diluted with ammonium iodide solution. The mixture passes to a device 32 where the mixture passes through a tube containing a charge of anion resin (28, Fig. 2, not shown), which retains the iodine and bromine and oly a small quantity of chlorine. The nozzle 14 is washed and turntable 10 rotated to make a second sample available to the nozzle 14. Also, the tube (28) of anion resin moves on one step, a tube containing a fresh charge taking its place in readiness for the second sample mixture. The chlorine and bromine are removed from the first charge of anion resin by washing with sodium nitrate solution, after which a new cycle carries the tube (28) forward a further step. This time, washing with hot magnesium nitrate solution removes the iodine which is carried by this solution into a tube 58. Air bubbles are removed from this flow by an ampoule 60 which is connected by pipe 62 to a water pump. At pump 68, air bubbles are introduced, together with predetermined proportions of sodium nitrite in concentrated nitric acid, and carbon tetrachloride. In coil 78, the sodium nitrite oxidises the iodine ions and in tube 80 filled with glass beads the iodine ions are extracted by solution in the carbon tetrachloride. The emulsion formed flows into a tube 86 for heating and to column 82 for distillation. The resulting distillate flowing down cooling tube 90 is a solution of iodine in carbon tetrachloride. This is mixed with hydroxylamine in ammonia. The sample is then delivered through tube 100 to be stored within the coil 102. The pump 106, having a higher flow rate than the others is started and conveys the sample to a loop 110, a buffer of detergent from pipe 112 following it. The sample remains in the loop 110 while a count is made. The count obtained from each sample is an indication of the iodine content of the sample. Mention is made of an alternative to the anion resin method of extraction, e.g. a method involving precipitation by means of reagents or filters. Measurements are also possible on urine samples instead of blood. The method is applicable to the determination of other halogens such as bromine. In the isolation of bromine, sodium nitrate solution is used to remove the chlorine, the bromine being then flushed out in magnesium nitrate solution and being extracted by distillation using carbon tetrachloride, after oxidising by potassium permanganate in sulphuric acid.