MODERN METHODS FOR THE SEPARATION AND CONTINUOUS MEASUREMENT IN THE GAS PHASE OF COMPOUNDS LABELED WITH RADIOCARBON RADIO AND REACTION GAS CHROMATOGRAPHY

Journal Article · Sun Sep 01 04:00:00 EDT 1963 · Angew. Chem. Intern. Ed Engl.

DOI:https://doi.org/10.1002/anie.196305401· OSTI ID:4043371

Drawert, F; Bachmann, O

S>Instrumentation for radio gas chromatography (liquid scintillation counters, ionization chambers, and GeigerMuller or proportional counting tubes) is discussed. Methods of measurement are described. Since there is no counting method available by which every /sup 14/C-labeled compound can be determined as such with good sensitivity and reproducibility, gas-chromatographic fractions were converted either into CO/sub 2/ by ignition or into methane before measurement of their radioactivity. In this way, there was no need to correct the results obtained since the measurement of a variety of radioactive compounds with different counting efficiencies is not involved. It was shown that the plateau length, and hence the counting efficiency, is constant for mixtures containing 20 to 40% methane and 80 to 60% hydrogen. For exploratory measurements, combination of a continuous-flow cuvette with a methane continuous- flow counter prove~ useful. The cuvette is separated from the counting chamber by a thin window, so that as a result of the spatial separation of carrier and counting gas, the results measured are relatively independent of the nature of the carrier gas. Several other experimental arrangements are described, one which permits discontinuous measurement of /sup 14/CO/sub 2/, and another, a continuous-flow proportional counting tube for continuous measurements, especially with hydrogen as carrier gas. Using hydrogen as carrier gas and (with admixture of about 10% of methane) as counting gas, the background effect of this counting tube lies under 100 impulses/min and becomes less with increasing additions of methane. The counting rate is substantially constant for methane contents of more than 30%. The plateau curves for selected hydrogen/methane mixtures, measured using a constant radiation source, are shown. A plot of different hydrogen/methane ratios in the gas mixture against the plateau length shows the optimum ratio (80 to 60% H/sub 2/; 20 to 40% CH/sub 4/). Some applications of radioand reaction gas chromatography are described: using the first experimental arrangement, mentioned above, investigations were made of the / sup 14/C-labeled alcohols arising from fermentations in the presence of added / sup 14/Cglutamic acid; fatty acids were analyzed after being convented into their methyl esters by treatment with boron trifluoride and methanol; saponification of K/sup 14/CN to /sup 14/Cformate was investigated to determine whether the reaction goes to completion and whether there are volatile byproducts; other problems, including transesterificntion, /sup 14/CO/sub 2/ assimilation by plants, and efficiency of hydrogenation catalysts. (BBB)

• Research Organization: Forschungsinstitut fuer Rebenzuechtung Geilweilerhof, Siebeldingen/Pfalz, Ger.
• NSA Number: NSA-18-017942
• OSTI ID: 4043371
• Journal Information: Angew. Chem. Intern. Ed Engl., Journal Name: Angew. Chem. Intern. Ed Engl. Vol. Vol: 2
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ALCOHOLS
AMINO ACIDS
BACKGROUND
BORON FLUORIDES
CARBON 14
CARBON COMPOUNDS
CARBON DIOXIDE
CATALYSIS
CHEMICAL REACTIONS
CHEMISTRY
CHROMATOGRAPHY
COMBUSTION
CONFIGURATION
CYANIDES
DIAGRAMS
EFFICIENCY
ERRORS
ESTERS
FATTY ACIDS
FERMENTATION
FORMIC ACID
GASES
GEIGER-MUELLER COUNTERS
GLUTAMIC ACID
HYDROGEN
HYDROGENATION
INSTRUMENTS
IONIZATION CHAMBERS
LABELLED COMPOUNDS
LABORATORY EQUIPMENT
LIQUIDS
METABOLISM
METHANE
METHANOL
METHYL RADICALS
MIXING
OPERATION
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDATION
PLANNING
PLANTS
POTASSIUM COMPOUNDS
PRODUCTION
PROPORTIONAL COUNTERS
QUANTITATIVE ANALYSIS
RADIOCHEMISTRY
RADIOISOT