High-resolution open-tubular columns in GC/MS

The pros and cons of various ways of connecting open tubular columns to a mass spectrometer will be discussed. Examples wil be given, showing the distinct advantages of glass connecting devices over metal interfaces. The main topic of this lecture will deal with the effect of subatmospheric operation on the performance of WCOT columns. Peak broadening in open tubular columns is satisfactorily described by the Golay-equation, extended to situations of appreciable pressure drop by Giddings. By diffirentiating this equation with respect to the carrier gas velocity, the opium separation conditions are found. In practice, however, several simplification on the calculated values of the minimum plate height and optimum carries gas velocity was studied. It was found that no simplifications can be allowed when the inlet-to-outlet pressure ratio is large, as with subatmospheric outlet pressures.