Simultaneous measurements of 22Na and 36Cl in aqueous samples: a comparison of three different methods

We have critically analyzed three methods that measure the combined presence of 36Cl and 22Na in aqueous samples. These were a sequential method, a dual-label spectral analysis method (Beckman 1983), and a AgNO3 precipitation method (Thompson 1983). The former requires the use of both a gamma counter and a beta liquid scintillation counter, whereas the latter two require access to a beta counter only. Our analysis suggests that investigators who have access to both a liquid scintillation counter and a gamma spectrometer would find the sequential method relatively simple to use and reasonably reliable. Those with access to only a liquid scintillation counter would be best advised to use the AgNO3 method described by Thompson.