A new method to determine δ³⁷Cl values of chloride in aquatic systems

A new technique was developed to analyse chlorine stable isotope ratios of chloride using Purge&Trap-gas chromatography-continuous flow-isotope ratio mass spectrometry (P&T-GC-CF-IRMS). The chlorine stable isotope analysis using continuous flow technology shows good reproducible results. This technique is much faster than the classical off-line method, needs smaller sample sizes and uses no toxic or dangerous chemicals. Because of its simplicity, this technique is also more cost-effective than other methods. Due to the determination of the δ³⁷Cl_SMOC value against an external standard (e.g., ISL-354) under the same preparative and chromatographic conditions, the precision and accuracy is comparable to or better than that achieved by any previous methods. This new technique allows more samples to be analysed rapidly and accurately. The P&T-GC-CF-IRMS technique will enhance the application of chlorine stable isotope ratio measurements in more research areas. It will allow the use of this analysis in studies where chlorine content is low and high precision and accuracy were important.

The method has been applied in different porewater studies to assess potential crystalline and argillaceous environments for the deposition of radioactive waste.