AN040: Plant Water: Accurate Water Stable Isotope Analysis of Organic Contaminated Water

AN040: Plant Water: Accurate Water Stable Isotope Analysis of Organic Contaminated Water

Picarro’s Cavity Ring-Down Spectroscopy (CRDS) instruments have become a globally accepted standard for the analysis of water stable isotopes from discrete liquid water samples, ambient water vapor and water extracted from solid matrices. Ease-of-use, lower cost, small footprint, and reliable performance have made these instruments an appealing alternative to Isotope Ratio Mass Spectrometers (IRMS), previously the only existing technique for such analyses.

Abstract: 

Picarro CRDS water analyzers and other laser optical systems (LAS) rapidly found success in geoscientific applications such as 1) ice core for paleoclimatology, 2) surface, groundwater, and rain water for hydrology 3) seawater for oceanography. However, as geoscientists expanded the applications and the types of water analyzed through such devices, they encountered interferences from organic molecules that compromised the isotopic measurements. Indeed, it was shown in peer-reviewed publications that certain organics, including some of those found in plant water, can shift the baseline of the water spectral curve or have their own spectral features which overlap with water characteristics resulting in deviation of the δD, δ18O or δ17O isotopic reading.

There are two potential methodologies for removing the effect of organics contamination of water samples. First, the spectroscopic treatment of signals attributed to organics. Second, the physical removal of organic compounds. Both possibilities have received significant interest, either alone or in tandem. Neither technique or combination of techniques have yielded straightforward methods applicable to all samples possibly contaminated with organics. However, Picarro has developed two products that are capable of making a significant contribution to scientists’ efforts in recording accurate water isotope data from plant waters and similarly composed samples.