Isotopic Gas Analysis Research Articles

Development of a compact real-time process gas analysis system for tritium accountancy for a DEMO fusion reactor by an application of laser Raman spectroscopy

In the fuel cycle of ITER and the future DEMO fusion reactors, which has many processes of tritium provision/ consumption/recovery/loss, such as, fueling, DT burning, vacuum pumping, purification, isotope separation and storage, detritiation, etc., tritium accountancy control will be required in its operation and safety management. In contrast to ITER, which will have frequent intervals between operations, a DEMO fusion reactor generating electricity must be operated continuously for long periods. This requires a dynamic tritium accountancy control, especially at the mass balance area boundary of the Tokamak including the vacuum vessel. To make a dynamic tritium accountancy system for a DEMO fusion reactor, based on our past work carried out during the ITER EDA, we are developing a new compact hydrogen isotope gas analysis system by the application of laser Raman spectroscopy advanced by technological progress in laser and detection systems. A prototype system has been made at TPL using a semiconductor laser with a Peltier-cooled CCD detector, with a simple optical system. Results of some preliminary tests being conducted to confirm sensitivity and accuracy under static and dynamic conditions are presented.

Isotopic gas analysis by means of mid-infrared photoacoustic spectroscopy targeting human exhaled air.

There is a great need for cost-efficient non-invasive medical diagnostic tools for analyzing humanly exhaled air. Compared to present day methods, photoacoustic spectroscopy (PAS) can provide a compact and portable (bedside), sensitive and inexpensive solution. We demonstrate a novel portable photoacoustic spectroscopic platform for isotopic measurements of methane (CH4). We identify and discriminate the 12CH4- and 13CH4 isotopologues and determine their mixing ratio. An Allan deviation analysis shows that the noise equivalent concentration for CH4 is 200 ppt (pmol/mol) at 100 s of integration time, corresponding to a normalized noise equivalent absorption coefficient of 5.1×10-9Wcm-1Hz-1/2, potentially making the PAS sensor a truly disruptive instrument for bedside monitoring using isotope tracers by providing real-time metabolism data to clinical personnel.

EGT-A sensitive time-of-flight mass spectrometer for multielement isotope gas analysis.

The principles of operation and figures of merit of a novel, compact (324mm×Ø 114mm; volume approximately 1000cm3 ) reflectron-type time-of-flight mass spectrometer designed for simultaneous multielement isotope gas analysis is presented. The system, which consists of a pulsed electron impact ion source, is designed either to directly analyse gas samples collected and stored in a compartment or samples extracted from solids using a CW laser system (fibre-coupled diode laser, <75W, λ=808±10nm). In latter case, laser pulses are focussed onto the sample surface to spot sizes of approximately 400μm in diameter that allows for direct ablation and vaporisation of solid sample material and releasing of trapped gases. A cleaning and trapping system that consists of various cold stages and getters is used before the gas enters the mass analyser. Measurements on various gases were conducted for performance evaluation, ranging from standard gases (Ar, Kr, and Xe) to trapped gases extracted from a sample of the Millbillillie meteorite. At optimised instrument settings, mass spectrometric measurements can be conducted with a mass resolution m/∆m of up to approximately 1200 (16 O and CH4 can be resolved), with a dynamic range of approximately 6 orders of magnitude and a mass calibration accuracy of approximately 100ppm. The high detection sensitivity of the system allows the detection of gas species at partial pressures down to the low 10-16 mbar level (corresponding to <10 particles/cm3 at standard temperature and pressure, including an ion transmission of approximately 80%). Measurements using standard gases demonstrated that the isotope ratios for a given element can be measured with an accuracy at the per mill level (relative to terrestrial values). Measurements of Ar extracted from the meteorite Millbillillie gave a 36 Ar/38 Ar ratio of approximately 1.6, which is in good agreement with literature values.

Isotopic gas analysis through Purcell cavity enhanced Raman scattering

Purcell enhanced Raman scattering (PERS) by means of a doubly resonant Fabry-Perot microcavity (mode volume ≈ 100 μm3 and finesse ≈ 30 000) has been investigated as a technique for isotopic ratio gas analysis. At the pump frequency, the resonant cavity supports a buildup of circulating power while simultaneously enabling Purcell spontaneous emission rate enhancement at the resonant Stokes frequency. The three most common isotopologues of CO2 gas were quantified, and a signal was obtained from 13C16O2 down to a partial pressure of 2 Torr. Due to its small size and low pump power needed (∼10 mW) PERS lends itself to miniaturization. Furthermore, since the cavity is resonant with the emission frequency, future improvements could allow it to serve as its own spectral analyzer and no separate spectroscopic device would be needed.

A preliminary study in determining the geographical origin of wheat using isotope ratio inductively coupled plasma mass spectrometry with13C,15N mass spectrometry

Commercially, wheat functionality and usage are dependent on the species and cultivars with each country tending to favour particular ones. Certain geographical origins attract a premium price so there may be a financial incentive to misdescribe grain or extend it via adulteration with cheaper varieties. A preliminary investigation was carried out to examine the utility of ICP-MS elemental isotope analysis of Cd, Pb, Se and Sr plus stable isotope gas analysis of 13C and 15N with multivariate statistics in identifying the country of origin of Triticum aestivum. The emphasis of this work was on differentiating USA, Canadian and European samples on the basis of their fingerprint due to underlying geogenic and anthropogenic differences rather than legislative borders. It was found that the samples in this pilot study could be geographically classified using a single analyte, δ13C and that the methodology shows some potential in identifying different cultivars and blends within a region using discriminant analysis. Further work, however, is required to confirm this and to determine if the methodology can be extended to identify the degree of sample adulteration.

Automatic isotope gas analysis of tritium labelled organic materials

Automatic isotope gas analysis of tritium labelled organic materials

Automatic isotope gas analysis of tritium labelled organic materials

An isotope analytical procedure and an automatic instrument developed for the determination of tritium in organic compounds and biological materials by internal gas counting are described. The sample is burnt in a stream of oxygen and the combustion products including water vapour carrying the tritium are led onto a column of molecular sieve-5A heated to 550 °C. Tritium is retained temporarily on the column, then transferred into a stream of hydrogen by isotope exchange. After addition of butane, the tritiated hydrogen is led into an internal detector and enclosed there for radioactivity measurement. The procedure, providing quantitative recovery, is completed in five minutes. It is free of memory effect and suitable for the determination of tritium in a wide range of organic compounds and samples of biological origin.

Automatic isotope gas analysis of tritium labelled organic materials

Automatic isotope gas analysis of tritium labelled organic materials

38. Distillation, organic chemistry, isotopic gas analysis

38. Distillation, organic chemistry, isotopic gas analysis

Isotope gas analysis of tritium-labelled organic compounds based on pyrolytical decomposition

A procedure has been developed for the activity measurement of tritium-labelled organic compounds in the gas phase. The organic compounds are pyrolysed in hydrogen carrier gas at 1150° and the decomposition products are swept through a carbon packing in accordance with the principle of the oxygen determination developed byUnterzaucher andBurger. The radioactive gas mixture obtained from the sample is swept by the hydrogen carrier gas flowing continuously through the reactor into a proportional counter tube, after the addition of propanebutane counter gas. By closure of the counter tube at a suitable moment, the radioactive gas is quantitatively trapped in the counter tube. The activity is measured in the limited proportional region. No memory effect occurs. The preparation of the sample requires 12 minutes; the relative standard deviation of analysis is <0.5%.

Isotope gas analysis of tritium-labelled water by means of an automatic apparatus

A procedure and an automatic apparatus designed for the radioactivity measurement of tritium-labelled water in the gaseous phase are described. The method is based on the conversion of water to hydrogen, methane and carbon monoxide in a carbon-packed quartz reactor. The reaction products are swept by hydrogen carrier gas into a piston-type counter tube. Methane is fed to the radioactive gaseous mixture, and the radioactivity of the hydrogen-methane-carbon monoxide mixture is measured in the limited proportional region. The radioactivity values are correlated with the weight of the sample taken and the results are corrected for the ‘memory effect’ obtained in the measurement of inactive water samples. The standard deviation of the procedure, characteristic of its reproducibility, is lower than ±0.5% rel. at preset number of counts.

III. Vacuum applications: 38. Distillation, organic chemistry, isotopic gas analysis

III. Vacuum applications: 38. Distillation, organic chemistry, isotopic gas analysis

Distillation, organic chemistry, isotopic gas analysis

Distillation, organic chemistry, isotopic gas analysis

38. Distillation, organic chemistry, isotopic gas analysis

38. Distillation, organic chemistry, isotopic gas analysis

38. Distillation, organic chemistry and isotopic gas analysis

38. Distillation, organic chemistry and isotopic gas analysis

Isotopic Gas Analysis for Biochemists

Isotopic Gas Analysis for Biochemists