Hydrogen gas chromatography

Van Schooten and Evenhuis [86, 87] applied their pyrolysis (500 °C)-hydrogenation-gas chromatography technique to unsaturated ethylene-propylene copolymers, i.e., ethylene-propylene-dicyclopentadiene and ethylene-propylene-norbornene terpolymers. The pyrograms show that very large cyclic peaks are obtained from unsaturated rings methylcyclopentane is found when methylnorbornadiene is incorporated cyclopentane when dicyclopentadiene is incorporated methylcyclohexane and 1,2-dimethylcyclohexane when the addition compounds of norbornadiene with isoprene and... 

The deterrnination of hydrogen content of an organic compound consists of complete combustion of a known quantity of the material to produce water and carbon dioxide, and deterrnination of the amount of water. The amount of hydrogen present in the initial material is calculated from the amount of water produced. This technique can be performed on macro (0.1—0.2 g), micro (2—10 mg), or submicro (0.02—0.2 mg) scale. Micro deterrninations are the most common. There are many variations of the method of combustion and deterrnination of water (221,222). The oldest and probably most reUable technique for water deterrnination is a gravimetric one where the water is absorbed onto a desiccant, such as magnesium perchlorate. In the macro technique, which is the most accurate, hydrogen content of a compound can be routinely deterrnined to within 0.02%. Instmmental methods, such as gas chromatography (qv) (223) and mass spectrometry (qv) (224), can also be used to determine water of combustion. 

Analytical Methods. Detection of carbonyl sulfide ia air can be done by gas chromatography or by combustion to sulfur dioxide and determination of the latter. Where hydrogen sulfide and carbonyl sulfide occur together, the carbonyl sulfide can be determined by combustion after hydrogen sulfide is absorbed by lead acetate, which does not absorb carbonyl sulfide (35). 

Concentration by gas chromatography has also been demonstrated. Elution chromatography has been used on an activated alumina column to resolve the molecular species H2, HT, and T2, thereby indicating a technique for separation or concentration of tritium (54). This method was extended (55) to include deuterium components. The technique was first demonstrated in 1964 using macro quantities of all six hydrogen molecular species (56). 

By using a flame ionization detector (FID), most compounds having a bond of carbon and hydrogen can be measured. This detector was originally developed for gas chromatography and employs a sensitive electrometer that measures the change in ion intensity resulting from the combustion of air... 

Hydrogenation of exocyclic, pyranoid vinyl ethers could afford a mixture of both possible 6-deoxy-D and L-hexoses. Our observations show that the proportion of each isomer is dependent upon the catalyst and the substituents on the vinyl ether. Thus, treatment of a methanol solution of l,2,3,4-tetra-0-acetyl-6-deoxy-/ -D-xylo-hex-5-eno-pyranose (12) with hydrogen in the presence of a palladium catalyst afforded a mixture which was shown by gas chromatography to contain 96% of the 6-deoxy-D-gluco isomer (11) and 4% of the 6-deoxy-L-ido isomer (13). In this... 

Thermal conductivity detector. The most important of the bulk physical property detectors is the thermal conductivity detector (TCD) which is a universal, non-destructive, concentration-sensitive detector. The TCD was one of the earliest routine detectors and thermal conductivity cells or katharometers are still widely used in gas chromatography. These detectors employ a heated metal filament or a thermistor (a semiconductor of fused metal oxides) to sense changes in the thermal conductivity of the carrier gas stream. Helium and hydrogen are the best carrier gases to use in conjunction with this type of detector since their thermal conductivities are much higher than any other gases on safety grounds helium is preferred because of its inertness. 

An important application of gas chromatography is its use for determination of the elements carbon, hydrogen, nitrogen, oxygen and sulphur in organic and organometallic samples. A brief account of the procedure used is given here,... 

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