High-precision δ¹³C and δ¹⁸O analysis of foraminifera underpins reconstructions of past ocean temperature, but the ~20 µg samples produce very little CO₂ relative to the internal volume of the sampling system.
This Technical Note describes how a two-stage cryogenic cold-finger process on the iso CARB PREP (or iso MULTI PREP) quantitatively collects the CO₂ to give a usable sample gas pressure at the ion source.