Patent Number: 6,297,501

Title: Simultaneous detection isotopic ratio mass spectrometer

Abstract: The invention comprises a mass spectrometer 1 and a method of mass spectrometry that is especially useful for the measurement of the isotopic composition of hydrogen in the presence of a helium carrier gas. Interference to the accurate measurement of the small HD.sup.+ peak at mass-to-charge ratio 3 by the much larger He.sup.+ peak at mass-to-charge ratio 4 is reduced by provision of an energy filter 35 in the ion detector assembly used to collect HD.sup.+ ions. This prevents ions of He.sup.+ which have lost energy through scattering, etc giving rise to a signal from the HD.sup.+ detector and distorting the deuterium hydrogen isotopic ratio measurement. Such a mass spectrometer 1 is typically used in conjunction with a continuous flow inlet system 4 based on an elemental analyzer that converts hydrogen present in a sample to gaseous hydrogen in a flow of helium carrier gas. Another embodiment of the invention provides a similar mass spectrometer useful for carbon or oxygen isotopic determinations in carbon dioxide gas.

Inventors: Merren; Thomas O. (Altrincham, GB)

Assignee: Micromass Limited

International Classification: H01J 49/30 (20060101); H01J 49/26 (20060101); H01J 049/32 (); B01D 059/48 ()

Expiration Date: 10/02/2018