Column and Instrumental Issues

Columns are brand new but have not been used (sitting in a box for multiple years). 

Columns have been exposed to multiple volumes of mobile phase. 

For point 1, the vendor may have changed the manufacturing or packing procedure for a particular bonded phase or column, respectively. The column vendor may have performed internal tests according to approved change control and other compliance procedures and have ensured with the probes they are using that the columns manufactured with the new process have not changed their inherent nature with respect to selectivity and retention of the 

For point 2, column performance can be adversely affected by pumping multiple volumes of mobile phase through the column due to (a) changes in the bonded-phase stability at various temperatures, pH values, and pressures and (b) accumulation of retained analyte components on the stationary phase. The maximum pH, temperature, and backpressure for which the column can operate versus the maximum number of column volumes should be known in order to avoid discrepancy in the data generated between laboratories (new versus aged column). For method transfer it is suggested that brand new unused columns (manufactured less than one year) should be used. 

Therefore, it is imperative to make sure column lot-to-lot reproducibility is demonstrated in the validation phase and are packed by the same vendor, and the vendor should be asked if any manufacturing changes have occurred for a particular column in order to minimize column robustness issues. 

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