Hydrogen, flame

Aluminium oxide occurs naturally as emery (an impure form) and as corundum. Corundum is a crystalline form which may be coloured by traces of impurity, for example as ruby (red) and sapphire (blue). Small synthetic rubies and sapphires have been made by heating alumina with the colouring oxide in an oxy-hydrogen flame. 

Atomic absorption spectroscopy is an alternative to the colorimetric method. Arsine is stiU generated but is purged into a heated open-end tube furnace or an argon—hydrogen flame for atomi2ation of the arsenic and measurement. Arsenic can also be measured by direct sample injection into the graphite furnace. The detection limit with the air—acetylene flame is too high to be useful for most water analysis. 

In a hydrocarbon analyzer using flame ionization, the sample gas is conducted along a heated sampling line to the detector, in the hydrogen flame of which the hydrocarbons are ionized into electrons and positive ions,... 

Wasseretoff-erzeuger, m. hydrogen generator, -flamme, /. hydrogen flame, -flasche, /. hydrogen cylinder. 

Although electrothermal atomisation methods can be applied to the determination of arsenic, antimony, and selenium, the alternative approach of hydride generation is often preferred. Compounds of the above three elements may be converted to their volatile hydrides by the use of sodium borohydride as reducing agent. The hydride can then be dissociated into an atomic vapour by the relatively moderate temperatures of an argon-hydrogen flame. 

We have also included R.F. (radio-frequency) current as a heating element, although it is only a heating method when employed with a suitable succeptor. Finally, one other method is listed for the sake of completeness, that of the oxy-hydrogen flame. It generates combustion products (H2O) but the RF- method can be used in any atmosphere... 

Heraeus A process for making clear, fused quartz by passing powdered quartz crystals through an oxy-hydrogen flame and collecting the product on a rotating tube of fused quartz. Invented by H. R. Heraeus in 1952 and developed by Heraeus Quartzschmelze, Germany. 

Vemeuil A process for growing single crystals of refractory compounds. The powdered material is dropped through an oxy-hydrogen flame and the product, consisting of microscopic molten droplets, is collected on a seed crystal. As the liquid mass reaches a cooler zone it crystallizes in the form of a single crystal known as a boule. Invented by A. V. L. Vemeuil at the Museum of Natural History, Paris, who made synthetic rabies and sapphires in this way. 

The absorption of the sulfur peak at 207 nm in an air-hydrogen flame is measured with a detection limit of 10 ppm sulfur. 

Plasma and urine levels of the drug are determined by chromatographing the trimethyl-silyl derivative of dobutamine on a 6-foot column packed with 3.0% UC-W98 silicon gum rubber (methyl-vinyl) on Diatoport S operated at 260°C. The hydrogen flame detector is maintained at 280°C. Helium flow rate is 60 ml/min. The retention time of dobutamine derivative (TMS) under these conditions is 3.8 minutes. This method measures plasma levels as low as 1 ig/ml (4). 

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