STOPPED-FLOW MASS-SPECTROMETRY WITH ROTATING BALL INLET - APPLICATIONTO THE KETONE-SULFITE REACT ION

A new device for continuous introduction of aqueous sample into a mass spectrometer, the rotating ball inlet, was used in the construction o f a stopped-now mass spectrometer. The rotating ball drags sample adhe ring to its surface past a polymer gasket into the vacuum of the mass spectrometer, where it evaporates and is ionized by electron impact. W hen the rotation of the ball is turned on or off, the mass spectrometr ic signal of an organic volatile solute responds with a half-time of 0 .1 s, indicating the intrinsic response time of the mass spectrometer, There are no other significant contributions to the response time, an d concentration transients with half-times down to 1 s can be recorded . Utilizing a now cell version of the rotating ball inlet in conjuncti on with a stopped-flow device, we have studied the reactions of aceton e and butanone with s(IV) species by recording transients in the conce ntrations of the ketones. Pseudo-first-order rate constants were deter mined at varying pH-values. Second-order rate constants for the reacti ons of sulfite and bisulfite ions with acetone and butanone were deter mined.