Introducing Simultaneous High-Precision C+D Analysis in One Integrated System: Deuterium and Carbon Isotope Analysis Made Simple

I've written a bit about using Picarro's Combustion Module for novel application methods and I wanted to let you know about a brand new product we are releasing - This is a CRDS analyzer that simultaneously measures stable isotope ratios of both carbon and its bound hydrogen directly from a combustion front-end. We're confident this new system is a significant advancement in capabilities for isotope measurements.

The combination of stable isotopic carbon (¹³C/¹²C) and carbon-bound hydrogen (D/H) has numerous applications in ecological, food, pharma, and forensics research.

• Food Traceability: ¹³C and D analysis can identify the likely country of origin of food products. Coffee is an example(Analytical and Bioanalytical Chemistry Volume 374, Number 5, 886-890). As a proof of principle, we have analyzed olive oil produced in various countries (see the graphic below and the new Application Note): Israel, Lebanon, Turkey, Greece, Italy, Spain, Australia, California (USA). Isotopic ratios clear differentiate between the different growing regions.
• Pharmaceutical quality control: Wokovich et al. (Journal of Pharmaceutical and Biomedical Analysis 38 (2005) 781-784) used these isotopes to analyze a bulk active pharmaceutical ingredient, Naproxen, from various production plants around the world. Similarly, Kurashima et al. (Forensic Science International Volume 189, Issues 1-3, 10 August 2009, Pages 14-18) used hydrogen isotope in combination with carbon and nitrogen to discriminate between synthetic, semi-synthetic, and bio-synthetic origins of ephedrine, as a precursor of methamphetamine.

• Bioplastic verification: Isotope ratios are being used to verify that incoming plastic is from renewable biological sources. 

• Animal migration: The migration of Monarch butterflies was tracked by Wassenaar and Hobson, who used ¹³C and deuterium isotope ratio analysis to identify their breeding sites (PNAS Vol. 95, pp. 15436-15439, December 1998).

• Drug enforcement: Law enforcement is now using isotope ratios to determine the source of marijuana and other illicit drugs (Science &Justice Volume 50, Issue 2, June 2010, Pages 86-93).  I have written about the U.S Customs and Border Protection's use of a Picarro Analyzer to determine the origin of marijuana in a recent blog.

However, up until now, the instrumentation involved in those analyses was very complicated, challenging to use and very costly to acquire. To analyze the stable carbon isotope in an automated continuous flow mode, researchers needed to employ the technique of elemental analysis coupled to IRMS (EA-IRMS) to generate CO₂ for the subsequent isotopic analysis of ¹³C/¹²C. This entailed the configuration of a front-end instrument to a separate interface modified to allow for reference gas pulsing and for conveyance of gas phase samples from the elemental analyzer to the IRMS instrument. And that was just for carbon analysis! 

To perform high-precision isotopic hydrogen analysis, researchers need to employ a completely different technique - a high temperature thermal conversion coupled to IRMS to generate molecular hydrogen for subsequent isotopic analysis (TC/EA-IRMS). So a lab seeking to analyze ¹³C and D in organic molecules had to be equipped with an IRMS with the right configuration of Faraday cups installed for it to permit the analysis of carbon and hydrogen isotopes in addition to the coupling of two separate front-ends (EA and TC/EA). The complications, expense, and hassle involved with using these techniques dramatically limits the use of isotopic ratio analysis in all these fields.

Which is why we decided to create a new and innovative instrument that is a dramatic improvement over the convoluted IRMS approach to make ¹³C+D analysis far less costly, far less time consuming, and far less complicated.  The new Picarro ¹³C+D Analyzer is an integrated instrument that includes a combustion module front end and a brand new Picarro Cavity Ring-Down Spectroscopy analyzer that can simultaneously and precisely measure ¹³C and D.  You can now use the ¹³C+D Analyzer to run a single sample and obtain both carbon and hydrogen isotopic information in a matter of 20 minutes.

What makes this analysis so fast and simple? It is the ability of Picarro's CRDS technology to make use of both the CO₂ and H₂O generated from the same sample combustion process in order to yield δ¹³C and δD in a single analysis with a precision that meets or exceeds the current performance of the two instruments combined (EA-IRMS + TC/EA-IRMS).  I'd like to call it the 2-in-1 approach that will enable you to leverage the dual isotopes applications in your research work, reduce the analysis time, cost-of-ownership, and daily operation with a simple-to-use system. When comparing the performance of IRMS to Picarro’s CRDS, it’s important to keep in mind that our precision guarantees are derived from actual sample combustion, unlike the specifications for IRMS. Their specs are based merely on gas standard pulses, and their stated precisions cannot be achieved with actual samples. I believe that, by making this type of analysis so much easier, scientists will create many new applications leveraging ¹³C and D isotope ratio measurements.

Finally, if you have specific application questions, I'd love to hear them and discuss them with you personally and thanks for reading.

Nabil Saad, Ph.D.

Picarro Senior Scientist