Novel Sample Pre-treatment Method for Improved Isotope Ratio Infrared Spectroscopy Measurement

Web Published:

Princeton Docket # 16-3212-1


Researchers at Princeton University, Department of Civil & Environmental Engineering, have developed a method to reduce spectral interference of organic contaminants in isotope ratio infrared spectroscopy (IRIS) through the use of solid phase extraction (SPE) technique.


IRIS is used for the stable hydrogen and oxygen isotope analysis of water sample. Volatile organic compounds (VOCs) such as methanol and ethanol in water samples which are extracted from plants can cause spectral interference in IRIS. This contamination reduces the accuracy of measurements, limiting the use of IRIS. The existing methodology of using activated charcoal for alcohol removal in environmental waters has been proven to perform poorly. According to inventors’ experiments, current market leading pre-combustion modules can only remove a total of 0.8% alcohols by weight from a contaminated solution. Pre-combustion can also harm isotope measurements if the total alcohol content is above this 0.8% threshold, which has been shown to be true environmental field samples.


This invention is a new procedure that can successfully treat samples with Ethanol up to 5% and Methanol samples up to 0.1%. In conjunction with the existing pre-combustion module, the resultant alcohol removal rate is above current standards for eliminating spectral interference in IRIS. This method utilizes a commercial SPE product that could easily be implemented in the current in-line auto-sampling module such that an added step prior to the pre-combustion module would significantly enhance the current technology. Implementing this procedure not only eliminates potential harm to measurements using the current IRIS method, but also optimizes the analyses themselves to allow for a new level of isotopic data collection from field samples.



•       Isotope Ratio Infrared Spectroscopy

•       Gas chromatography

•       Air pollutant detection

•       Tracing of irrigated waters in nature



•       Effective in removing organics

•       Easy to implement

•       Low cost

•       Can be incorporated in the current in-line auto-sampling module


The Inventor


Elliot Chang is an environmental scientist with a core interest in interfacial chemistry. Conducting adsorption studies since 2008 at New York University’s Kallenbach Lab, Elliot has since grappled with more complex problems related to surface chemistry with Princeton University’s Ecohydrology Lab. During Elliot’s time at Princeton, he focused on inventing a non-destructive environmental water purification protocol for enhanced isotope ratio infrared spectroscopy. Through academic collaborations with UC Berkeley’s Center for Stable Isotope Biogeochemistry and Princeton’s NMR Facilities, and discussions with companies like Picarro Inc. and Los Gatos Research, Elliot was successful in inventing a water purification protocol, resulting in a publication in Rapid Communications in Mass Spectrometry (2015) and a pending patent on this technology. Elliot graduated Princeton University in May 2016 with a Bachelor Degree of Science in Engineering, majoring in Civil and Environmental Engineering and minoring in Sustainable Energy. He is a member of the Sigma Xi Honor Society and the American Geophysical Union and will start a PhD in environmental science, policy, and management at UC Berkeley in Fall 2016.


Intellectual Property & Development status

Patent protection is pending.

Princeton is currently seeking commercial partners for the further development and commercialization of this opportunity.




Anthony Williams

Princeton University Office of Technology Licensing

• (609) 258-3769•

Xin (Shane) Peng

Princeton University Office of Technology Licensing

• (609) 258-5579•


Patent Information:
For Information, Contact:
Tony Williams
Princeton University
Elliot Chang
Kelly Caylor
Adam Wolf
earth science
gas sensing