Reversed-phase membrane inlet mass spectrometry applied to the real-time monitoring of low molecular weight alcohols in chloroform.

Reversed-phase membrane inlet mass spectrometry incorporating a hollow-fiber Nafion membrane has been evaluated for the determination of low molecular weight alcohols in chloroform. The hydrophilic Nafion membrane preferentially transports methanol and ethanol, allowing percentage concentrations of the alcohols to be determined in a chloroform matrix. A linear response was observed for ethanol over the working range 0.5-2.5%, with a limit of detection of 0.1%. The application of reversed-phase membrane inlet mass spectrometry using a Nafion membrane to the monitoring of a chloroform recovery process has been investigated using a residual gas analyzer. Evolving methanol and ethanol concentrations were determined in real time and compared favorably with off-line determinations by gas chromatography.