We have a GC with a calibration gas of the following concentration: CO = 2.5 ppm CO2 = 4.5 ppm C2H2 = 1.0 ppm CH3OH = 1.0 ppm N2 = Balance The methanol peak is missing and the GC commissioning engineer was unable to fully solve the problem. Prior suspicion on the calibration gas proved unfounded since we have already used gases from four different manufacturers. Valve switching timing is also not the problem since we ran the calibration with the column valves forced ON. Recently, someone suggested that the problem could be that the methanol is sticking to the cylinder walls. Is this accurate? I have heard that many plants also have this problem with methanol. Would a teflon-lined cylinder solve the problem?