This proposed multi-laboratory project aims to develop urgently needed organic hydrogen, carbon, and nitrogen isotopic reference materials (RMs) that will serve the international community for one to several decades with reliable stocks of RMs. Modern, semi-automated stable isotope-ratio analysis (SIRA) in continuous flow mode with on-line elemental analysis (EA), gas chromatography (GC), or liquid chromatography (LC) interfaced with isotope ratio mass-spectrometry (IRMS) has become a routine and invaluable tool in monitoring of climate change, studies of ecology, environmental sciences, fossil fuel and biofuel sciences, food science, forensics, and medical sciences. Accurate determinations of hydrogen, carbon, and nitrogen stable isotopic compositions require a calibration using at least two isotopic RMs (also called standards) having different isotopic compositions to (i) anchor the isotopic scale and (ii) compensate for differences in operation of instruments, which commonly compress isotope scales. The development of suitable organic stable isotope RMs has not kept pace with the rapid development of analytical continuous flow methods. The U.S. traditionally has been an international leader in the development of stable isotopic RMs, but the National Institute of Standards and Technology (NIST, formerly NBS) now fails to adequately serve the stable isotopic RM needs of the scientific community. As a result, the scientific community is forced to work with temporary laboratory isotopic RMs jeopardizing the mutual compatibility of scientific results among different laboratories. Several of our new organic isotopic RMs will be the first and only RMs for NIST for H, C, and N isotopic calibration of modern gas chromatographic and liquid chromatographic approaches. An additional result of the proposed project will be to recommend improved, accurately calibrated hydrogen isotopic compositions for all inorganic and organic hydrogen RMs relative to the scale-defining international measurement standards. Distribution of newly developed RMs will occur via NIST and IAEA, and also via discounted channels to support NSF-funded applications.
The fields of chemical and biological oceanography, ecosystems, and Geobiology/low-temperature geochemistry use stable isotope analyses as cornerstones for discovery and innovation. They will obviously benefit from having a source of standard materials, so that the results coming from these communities can be precisely compared. Diverse fields beyond geochemistry will benefit from new stable isotopic RMs, e.g. biofuel energy research, forensic tracing of contaminants and animals, biology and ecology (e.g., trophic research), medical science (diagnosing medical disorders), pharmacology (drug authentication), criminal justice (geographic tracing of human remains), and food science (food authentication). The PI has been volunteering in outreach efforts, for example by teaching the Geology Merit Badge to local boy scouts. When the use of stable isotope research was explained to young listeners or the public, the response was always enthusiastic to prominent forensic examples and the fact that RMs from my laboratory at Indiana University are being used by the FBI, EPA, IAEA, U.S. and international customs authorities. Results of this research will also be presented at the IU Crossroad Geology Program, which is an event run by the department?s graduate students aimed at sharing research with undergraduates, graduates from other institutions, and to visitors from industry.
Stable isotopes in all kinds or organic matter express no radioactivity and can be used as highly diagnostic indicators for food authenticity, in forensic applications, and to decipher climate change signals in organically grown or deposited materials (e.g., tree rings, sediment sequences). Ecological studies use stable isotopes to track the migration pathways of animals and to clarify what and where organisms eat. Measurements of stable isotope abundances require adequate standards for calibration against unified international stable isotope abundance scales. In the past, there were very few organic standards available that often did not apply to the needed measurements. People were forced to use minerals or salts to calibrate organic samples, which is like comparing apples and organges. Our group of ca. 10 laboratories from 7 countries prepared and calibrated a suite of 19 organic compounds as new international organic stable isotope standards. Amino acids, hydrocarbons, and caffeines are among the new standards that are already being distributed by one of our member laboratories at the U.S. Geological Survey. The International Atomic Energy Agency in Vienna/Ausrtria will eventually follow suit. Indiana University will serve as a third outlet. We prepared enough of the standards to last for several decades. Some of our standards incorporate special features like placing heavy isotopes at specific positions within a given molecule. Although such sophistication cannot yet be measured with today's instruments, we are confident that new methodologies will be able to take advantage of these built-in characteristics in the upcoming years. Finally the available suite of organic stable isotoipe standards is ahead of its time.
