Eichrom’s Tritium Column is designed to replace distillation for most routine tritium analyses of aqueous samples. The column works by removing potential interferences in the LSC spectrum, just as distillation does. It is not intended to be an enrichment procedure, and as such, it should be used only in situations where the required detection limit can be achieved by the direct counting of a 5-10 mL aliquot of the sample (plus cocktail) processed through the tritium column.

Figure 1 shows the composition of the Tritium Column and Table 1 explains the purpose and capacity of each component. The Diphonix® Resin removes cations in exchange for hydrogen ions and its theoretical capacity is 0.8 mEq per column. The anion resin is standard chloride form analytical grade 1X8 resin. It exchanges anions in the sample for chloride ions. (It is recommended that the sample pH be >1.) The polymethacrylate component removes organically bound tritium and carbon-14.

Table 1

Component Target Capacity
Diphonix® Resin Cations 0.8mEq
Anion Exchange Resin Anions 0.8mEq
Polymethacrylate Resin Organic Molecules 50 mg

Table 2 shows the average spike recoveries for a variety of sample matrix types passed through the Tritium Column.

Table 2
Spike Recovery Results using Tritium Column

Sample Type Volume 3H Spike (Bq) % Recovery
Distilled water 15mL 97.2 96.4% (n=4)
Distilled water 25mL 20.2 87.6% (n=4)
Distilled water 25mL 19.5 94.9% (n=7)
Ground water 25mL 17.1 91.2% (n=5)
Sea water 25mL 4.0 90.0% (n=6)
Urine 25mL 85.1 91.1% (n=4)

The column successfully removes potential radioactive interferences. In a study performed at Eichrom, a mixture of radioisotopes (60Co, 137Cs, 233U, 90Sr/90Y, 210Pb, 230Th, total activity 16.9 Bq) was spiked into eight tritium-spiked solutions (distilled and sea water samples). In every case, after passing the sample through the Tritium Column, the number of counts in the region above the tritium window was not different than the number of counts in the same region of an un-spiked sample. (See Table 3 )

Table 3
Results of contamination study

Sample Type Volume 3H Spike (Bq) Contaminant
spiked (Bq)
Contaminant
found(Bq)
Distilled Water 25mL 19.5 16.9
Distilled Water 25mL 20.2 16.9
Sea water 25mL 4.0 16.9

In another experiment, Daniel Cahill of Carolina Power & Light measured the activity of fission and activation products in PWR and BWR reactor coolant samples before and after passing through Eichrom’s Tritium Column.Table 4 summarizes the before column activity of each sample. After the column, no measurable activity was detected in the BWR sample and only a trace level of activity of 60Co with > 50% counting error was detected in the PWR sample. Because the amount of 60Co measured was so low and the error so high, and because the BWR sample contained more than 10 times the 60Co before the column and none after the column, it is assumed that the trace amount measured in the PWR sample is an artifact due to the background of the gamma counter.

Table 4
Carolina Power & Light Samples

Isotope PWR Sample BWR Sample
Cr-51 2,900 1,999
Mn-54 518 5,590
Co-58 4,740 4,960
Fe-59 109
Co-60 392 5,990
Sn-113 230
Nb-95 4.220 116
Zr-95 2.210
I-131 14.200  —
Cs-134 1,120  —
Cs-137 1,320  —
La-140  — 1,550
Ce-144  — 203

D. Cahill, Carolina Power & Light, New Hill NC

See our newsletter archive for additional data on the performance of Eichrom’s Tritium Column. The studies reported here, and elsewhere on our website, conducted in Eichrom and customer laboratories, demonstrate that the Tritium Column performs equivalently to the traditional distillation technique. We encourage you to try using this column as a substitute for distillation of your aqueous tritium samples.

Eichrom’s Tritium column is manufactured as a 2mL pre-packaged column (total bed volume of all three components.) It is available in packages of 20 and 50. Click here for part numbers and descriptions.