GC060 Column Length

 The longer the column, the greater the plate number, N, and better separations are obtained. Resolution, Rs, however is proportional to the square root of column length. Resolution only increases by the square root of 2 (41%) if the length is doubled.

Retention time, tR, is also proportional to column length. For fast analysis, reduced length columns are advised. Nevertheless, when resolution is critical, long columns are required. They are used for complex samples (50 components or more). The drawback of long columns are the long analysis times.

Columns between 15 to 30 m are recommended for most applications, because they provide a good compromise between analysis speed and resolution.

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