GB904165A - Improvements in means for the quantitative analysis of deuterium in hydrogenated compounds - Google Patents

Abstract

<PICT:0904165/III/1> <PICT:0904165/III/2> The proportion of deuterium in hydrogen-containing compounds is determined by vaporizing the compound to be tested, if necessary, reducing the vapour by passing over heated uranium and passing the so-formed hydrogen and deuterium to a mass spectrometer in which ions of atomic mass two (H2+) are separated from those of atomic mass three (HD+). In the illustrated embodiment (see Fig. 1), a mass spectrometer tube 1 is attached via tube 2 to a pumping p arrangement maintaining the desired vacuum in said spectrometer and via tube 3 to a gas line 5 (illustrated in detail in Fig. 2) in which the desired vacuum is maintained by pump 4. The gas line 5 comprises a liquid nitrogen trap 21; a tap 22a by which the gas line can be isolated from the pump 4; a tap 22b controlling an inlet 25 for non-gaseous samples (e.g. a liquid such as water which can be introduced on a platinium helix 31 mounted on a plug 32, drawn to larger scale); a tap 22c controlling an inlet 26 for gaseous samples, e.g. hydrogen sulphide; a tap 22d whereby the introduced samples may be allowed to flow into an expansion bulb 23 and the uranium reduction section. The latter consists of a silica U-tube 29 containing two very thin tapes, 28a, 28b of uranium, contained in an oven in which a temperature of 570 DEG -630 DEG C. may be maintained. The reduction section is entered by means of a capillary tube 27 and the hydrogen and deuterium leave through capillary tube 30. The taps, expansion chamber and capillary tubes may be heated by means of electric elements E, E1 to prevent condensation. The sample after reduction to form deuterium and hydrogen passes into the spectrometer tube and the resultant separate ion streams of H2+ and HD+ are received by collectors 11 and 12 respectively. The ion currents may be separately amplified (see Group XXXVI), compared and the result employed to determine the concentration of deuterium in the hydrogen. The apparatus may first be calibrated by means of known mixtures of light and heavy water which also contain hydrogen sulphide. In Fig. 1, the pumping system for the mass spectroscope comprises a primary pump 13 of the vane type in series with two mercury diffusion pumps 14 and 15, the former of which has an ejector. A carbon dioxide trap 16 is also provided, and there is preferably a constriction between this and the pump 15.