Abstract
The role of water vapor as an impurity in glow discharge mass spectrometry is examined by means of pulsed injection of water into an argon discharge. The effect of water vapor on both analyte and intrinsic gas species is determined. Water dissociates in the discharge to produce reactants that can influence analytical results. The extent of this effect is dependent on the reactivity of the cathode sample with water and its dissociation products. Metal oxides are observed during and shortly after the pulsed water injection. Three different cathode materials (titanium, iron, and copper) are studied, with a range of metal oxide bond strengths. Titanium, which has strong gettering action in the glow discharge plasma, exhibits the shortest perturbation time after addition of water vapor. The experiments show the need to remove trace water from glow discharges for best analytical results.
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