Validation of the Quench Curve for the analysis of organically bound tritium in environmental matrices by liquid scintillation spectrometry

Tritium (³H) present in environmental matrices can be classified into (i) ³H atoms attached to bio-organic molecules of tissue and not exchangeable with plant water is Organically Bound Tritium (OBT), and (ii) ³H atoms attached to water molecules/organic molecules and exchangeable with plant water is Tissue Free Water Tritium (TFWT). The measurement of OBT in environmental matrix is quite challenging since it demands accurate analytical methods to separate OBT from the samples and highly sensitivity instruments for detection. Thermal oxidation is one of the methods employed for the separation of OBT from environmental matrices. One of the difficulties associated with this technique is quenching (chemical and color quenching due to sample, absorber and scintillator characteristics), which results in the loss of counts and hence reduction in counting efficiency. To determine absolute sample activity in DPM, it is necessary to measure the level of quench of induced by the samples and then evaluate corresponding counting efficiencies. In this paper we present the generation of quench curves for accurate estimation of OBT concentration in environmental samples and the validation of the curve by the analysis of the reference material