The large-scale column pack qualification pulse injection testing used flow rates different from the chromatography elution
step flow rate. In addition, the previous pulse injection and elution phase compositions had ionic interactions with the media.
The ionic interactions led to qualification results that deviated from ideal asymmetry for the resulting peak. The pulse injection
and elution flow rates were changed to match that of the process and a different testing media consisting of a 0.1 M sodium
chloride solution/1.0 M sodium chloride pulse injection. This combination reduced the ionic interaction effects on the elution
profile. By minimizing these effects HETP and peak asymmetry values measured by this method gave a greater sensitivity to
the quality of flow distribution. This procedure was used to test all column packs in this study.
Figure 8. High compression bed stability
High (1.18) and low (1.09) compression packs were exposed to stress cycles induced by high flow rates on a single pack. Figure
7 shows that the column packed at the lower 1.09 compression displayed a tendency toward increasing peak asymmetry values
with increasing chromatography cycles. Figure 8 shows superior stability over the column lifetime at higher compression as
indicated by the repeatability of the elution profile with repeated cycles.
By comparing the elution profiles for each compression, the higher compression pack suggests increased bed stability toward
cycle stresses.
