Hey there
Is it allowed to change column length which will be smaller or larger as opposed to mention it in method of analysis
Regards
Please mentioned which type of column you talking? HPLC or GC?
Hplc column
Particle size (HPLC): For isocratic separations, the particle size and/or the length of the column may be modified provided that the ratio of the column length (L) to the particle size (dp) remains constant or into the range between −25% and 50% of the prescribed L/dp ratio. Alternatively (as for the application of particle-size adjustment to superficially porous particles), other combinations of L and dp can be used provided that the number of theoretical plates (N) is within −25% to 50%, relative to the prescribed column. Caution should be used when the adjustment results in a higher number of theoretical plates that generate smaller peak volumes, which may require adjustments to minimize extra-column band broadening by factors such as instrument plumbing, detector cell volume and sampling rate, and injection volume. 1S (USP40) For gradient separations, changes in length, column inner diameter, and particle size are not allowed.