Elimination of water interference in pulsed glow discharge time-of-flight mass spectrometry

The presence of water in the discharge cell is a serious problem in glow discharge mass spectrometry. Even very small quantities of water can make considerable changes in the composition and electrical parameters of the plasma, which lead to a decrease in the signal intensity and the appearance of various cluster components. This results in a very complicated mass spectrum and significantly deteriorates the analytical performance of the method. Different approaches to solving the this problem are discussed in the paper. A multiple position interface that allows analyzing 6-10 samples without decapsulation of the discharge cell is presented in this work. It is also shown that the use of a tantalum auxiliary cathode ensures a several-order depression of the interfering components (OH+, OH (2) (+) , OH (3) (+) , (CH)-C-12-H-1 (2) (+) , O-16(+), (CH)-C-12-H-1 (3) (+) ) because of its getter behavior. The simultaneous application of all proposed approaches ensures solving the problem of interferences in the combined hollow cathode with pulsed glow discharge to the great extent.