Methane Carbon Isotope Analyzer (CH4, δ13C) Overview

Due to its rugged, field-portable packaging, the Methane Carbon Isotope Analyzer is ideally suited for energy exploration, biogas production and for studies of anaerobic digestion, methanogenic bacteria, methane hydrates, hydrothermal vent effluents, and other applications involving isotopic ratios in methane. The Analyzer provides sub parts-per-mil precision of δ13C in methane with a rapid response time.  Because it does not require user intervention, this instrument also enables long-term methane isotope monitoring studies.

Based on high-resolution direct absorption spectroscopy, the Methane Carbon Isotope Analyzer provides an absolute, accurate measurements of 13C/12C in methane (δ13CH4) without the need for frequent use of expensive reference gases. The instrument includes an internal computer that can store data practically indefinitely on its internal hard drive (for applications requiring unattended long-term operation) and send real-time data to a data logger through its analog and digital (RS232) outputs. In addition, an Ethernet connection allows remote access to data files stored on the instrument’s hard drive.

The analyzer uses LGR’s patented Off-axis ICOS technology, the fourth-generation cavity enhanced absorption technique, which employs a high-finesse optical cavity as the measurement cell. LGR’s technology has many proven advantages over conventional first-generation cavity ringdown spectroscopy (CRDS) techniques. In brief, since the laser beam does not have to be resonantly coupled to the measurement cell (i.e. precise beam alignment is not critical), LGR Analyzers are simple to build, relatively inexpensive, and inherently robust thermally and mechanically.  In addition, since LGR’s technology can record reliable absorption spectra over a far wider range of optical depths (absorbance values) compared with conventional CRDS, LGR Analyzers provide measurements over a much wider range of mole fractions (gas concentrations). Finally, due to the ease and simplicity of recording and quantifying the measured spectra using LGR’s Off-Axis ICOS, all LGR Analyzers display the entire absorption spectra to the user in real time allowing for immediate system diagnostics and performance validation. 

In addition, the availability of many value-added options extends the abilities of the unit to include measurements of discrete samples (collected in bags or vials, for example) and to automatically handle multiple inlet sources (e.g., from towers or distributed sites) for uninterrupted measurements over periods of weeks.

As with all LGR analyzers, the Methane Carbon Isotope Analyzer may be controlled remotely via the Internet. This capability allows the user to operate the analyzer using a web browser practically anywhere Internet access is available. Furthermore, remote access allows bios-level control of the instrument and provides the opportunity to obtain data and to diagnose the instrument operation without being on site.