Boreas: A Sample Preparation-Coupled Laser Spectrometer System for Simultaneous High-Precision In Situ Analysis of δC and δH from Ambient Air Methane.

We present a new instrument, "Boreas", a cryogen-free methane (CH) preconcentration system coupled to a dual-laser spectrometer for making simultaneous measurements of δC(CH) and δH(CH) in ambient air. Excluding isotope ratio scale uncertainty, we estimate a typical standard measurement uncertainty for an ambient air sample of 0.07‰ for δC(CH) and 0.