Software-Based Method to Flag Water Samples Contaminated with Trace Organics Such as Methanol and Methane

Software-Based Method to Flag Water Samples Contaminated with Trace Organics Such as Methanol and Methane

ChemCorrectTM  is an innovative software system that provides researchers with an unparalleled level confidence in their isotopic water sample fidelity. It also allows researchers can reprocess their data to correct for the spectral irregularities caused by contamination.

Abstract: 

The Picarro L2120-i is a high-performance stable isotope analyzer for liquid and vapor water samples. The L2120-i analyzer utilizes a time-based optical measurement technique called Cavity Ring-Down Spectroscopy (CRDS). With this technique, the analyzer simultaneously measures values for δ18O and δD from optical spectra of specific stable isotopologues of water (H216O, H218O, and HDO). A typical optical spectrum is shown in the figure to the left. CRDS quantifies the optical absorption by measuring the rate of decay (the ring-down) of laser light in a cavity containing a gaseous sample. Increased sample concentration leads to faster decay mechanisms (via molecular rotation & vibration) and a faster ring-down time. The laser is tuned across the spectrum.At each key spectral point a ring-down curve is collected. The full range of ring-downs are then processed into a spectral image. The laser wavelength is controlled using a patented wavelength monitor. This level of control results in incredibly stable spectra as well as highly quantitative concentration and isotope analyses.