Apparatus and method for isotopic ratio plasma mass spectrometry

摘要

The invention comprises a method and apparatus for inductively- coupled plasma mass spectrometry which is particularly suitable for the determination of isotopic ratios.PPIn order to improve the precision of such determinations, the nozzle-skimmer type interface of the mass spectrometer is arranged so that the ratio ##EQU1## is greater than 0.8 mB.sup.1/2, where d.sub.s is the diameter of the orifice in the skimming member, s is the spacing between the sampling member and the skiming member, and p.sub.1 is the pressure in the region between the sampling and skimming members. Although use of the invention slightly reduces the efficiency of the interface it results in more accurate isotopic ratio determinations.