Our work horse has been for many years a ThermoFisher Delta Plus XL which we replaced in 2017 by a Delta V Plus. The mass spec is linked with a Gasbench II which we use primarily for isotope analysis of calcite; we also run aragonite, dolomite, magnesite and siderite samples. The principles of continuous-flow isotope ratio mass spectrometry of carbonates is described in Spötl & Vennemann (2003).
We have since optimized the method for high-throughput of carbonate samples and now routinely run ca. 30,000 samples on an annual basis. See this article for further details: Spötl (2011)
A method for carbon isotope analysis of dissolved inorganic carbon (DIC) in water samples was reported in Spötl (2005).
Samples for carbon isotope analysis of carbon dioxide in cave air are directly taken using Helium-flushed 10 ml exetainer vials. We also sample soil gas using a simple soil probe as described in Spötl (2004).
We also use a Picarro L2140-i CRDS instrument for water isotope analysis.