Question

What might be a disadvantage of having too long of a column in gas chromatography?

Answer 1

As in the gas chromatography longer columns provide greater resolution, but increase back pressure. It should be stressed that doubling column length will NOT double resolution (resolution only increases according to the square root of the column length). If resolution between a critical pair is less than 1, doubling column length will not bring it to baseline (resolution value of at least 1.5). Increasing column length to increase resolution should be considered as a last resort. A more effective approach to increasing resolution is to reduce column I.D.