I am trying to calibrate my GC with a single Calibration Cylinder (2%H2, 98%N2). I am measuring H2 with a TCD. The sample goes through a 6 port switching valve through a sample loop to vent, and then gets injected through a split/splitless inlet onto the column and then to the TCD.

Has anyone ever calibrated a GC by partial pressure? Using the 2% H2 cylinder and changing the pressure in the sample loop to change the partial pressure of H2 (mole fraction of H2 times the total sample loop pressure). I get a good linear curve with low errors for H2 from 20ppm to 20% but when I try to calibrate with a H2 mass fow controller and N2 mass flow controller at a constant sample loop pressure the calibration curve is also very linear and has low errors but the slope is different to the partial pressure calibration.

Thanks,

Michael