Method translation and retention time locking in partition GC

Method translation in gas chromatography (GC) is a variation of components (columns, carrier gases, detectors, etc.) and parameters (pressures, temperature programs, etc.) of a method in away that maintains the peak elution pattern. The concept is based on the fact that the void time can be viewed as a universal time unit in GC; method translation is the scaling of the time axis of the temperature program relative to the void time. Method translation can be used to reduce analysis time, improve resolution, and adopt a method to a different carrier gas or to a different outlet pressure (vacuum for mass spectrometers, ambient pressure for conventional detectors, etc.). It can also be used for retention time locking (RTL). Theoretical and practical aspects of method translation and RTL are analyzed. It is shown that a constant-pressure method can be translated between the columns that have the same stationary-phase type and phase ratio. Method translation also implies that optimum temperature ramp rate (expressed in degrees C per void time) can be the same for a broad class (maybe all) of temperature-programmed GC analyses. For partition GC, this rate is similar to 10 degrees C/void time.