AN 19 - Automated Measurement of δ18O and δD in Briny (Salty) Samples

Many real-world aqueous samples contain dissolved salts. Ocean water has a salt concentration of around 3.5% by weight. Samples at this concentration and higher are commonly referred to as “briny.” A potential problem in any analytical instrument used with briny samples is build-up of salt crystals due to precipitation. With some techniques, this can quickly lead to physical clogging, in others it can impair optical or electronic performance. One of the recognized advantages of WS-CRDS isotope analyzers is their ability to obtain precise δD and δ18O isotope ratios directly from aqueous samples without persistent memory effects and without resorting to distillation or any other time-consuming sample preparation methods. In this application note we present the results of an extended series of injections designed to investigate whether these advantages would also hold true for briny samples. The results of this study clearly confirm that large numbers of briny samples can be automatically processed with confidence. The ability to process raw briny samples in real-time is of relevance for scientists studying ocean water and salt lakes, and is also of particular advantage to petrochemical exploration efforts where it provides an extra dimension of information when analyzing the samples associate with mud logging.