Every column has a limited lifetime.
Good resolution can be completely ruined by a loss in efficiency of a damaged or dirty column, which can be the result of improper handling of the column.
Typical GC column problems are:
The plate number and the plate height are used by manufacturers in test reports to express the efficiency and quality of the columns. It is recommended to determine the plate number after installing a new column:
A manufacturer performs column tests under optimum conditions: correct installation of the column, optimum gas velocity, minimal external causes for efficiency loss etc. If, however, the user finds plate numbers that differ substantially form these values for one or more columns, this is an indication that something is wrong with the system.
A periodical test (e.g. once a month) can provide information about the decline of quality of the column in particular. -