The retention behavior of a heterogeneous group of solutes has been examined on seven different stationary phases under isothermal and temperature-programmed conditions. Both AH, (enthalpy of solute vaporization from the stationary phase) andAS, (entropy of solute vaporization from the stationary phase) valbes were determined for each solutestationary phase combination under isothermal conditions. Both program rate and carrier gas velocity were shown to affect solute elution order. Unless these and other experimental factors discussed are controlled, column equivalency studies based on solute elution order have dubious value.

Environmental analytical procedures in the United States are largely based on Environmental Protection Agency (EPA) methods. Different procedures have been adopted by the European Union (EU). In the United States, the determination of volatile organic compounds in drinking water employs purge and trap sampling followed by gas chromatography with photoionization and electrolytic conductivity detection. European analysts perform an "equivalent" priority pollutant analysis using static headspace injections and electron-capture detection. Some of the compounds included on the EPA list (1) do not appear on the EU lists (2) and vice versa. A distinctive difference is the use of megabore (greater than 0.45-mm i.d.) capillary columns in the EPA methods. European analysts are reluctant to adopt these columns in their methodologies. In this work, several open-tubular column dimensions are investigated and optimized with particular attention given to problems encountered when columns are interfaced to purge and trap or static headspace analyzers. Also, EPA and EU priority pollutant methods are contrasted according to the method of detection.

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