A quadrupole‐based mass spectrometric system for the determination of noble gas abundances in fluids

We present details of the operation and performance of a quadrupole mass spectrometer‐based system developed for the extraction, separation, and high‐precision measurement of noble gases dissolved in fluid samples. The relatively inexpensive quadrupole mass spectrometer system, employed with the isotope dilution technique, achieves a precision for He, Ne, Ar, Kr, and Xe abundances of ±0.4%, ±0.7%, ±0.1%, ±0.8%, and ±0.9% respectively, as determined from analyses of mixed spike‐air aliquots. The system has an overall accuracy of ±0.6°C on the noble gas temperature of a water sample, as determined by analyses of water samples air‐equilibrated under controlled conditions. We describe improvements in calibration procedures and sample processing protocols that have led to these high‐quality measurements.