Using on-line HPLC to Enable Unique Operational Approaches
Most biotech processes involve multiple column chromatography steps to achieve adequate purification of the biosynthetic origin
product. By using on-line HPLC, Eli Lilly and Company was able to successfully combine two process-scale ion exchange chromatography
steps into a single, automated process.1 This process is explained in Figures 2 through 7.
Figure 2 shows the two process chromatography columns combined using one three-way and two four-way process valves to enable
the columns to be operated either in parallel (i.e., as two independent columns) or in series (i.e., as one continuous column)
and to allow the eluent stream to be diverted to the waste stream or product collection tank. In this operation, an on-line
HPLC analyzer automatically samples and determines the purity of the product in the column eluent stream. The DCS uses these
data to determine the appropriate position of the process valves (to operate the process columns either in parallel or series)
and to divert the eluent stream to waste or to the product collection tank.
Figure 2. Two process-scale columns combined into a single operation. The positioning of the on-line HPLC downstream of the
first four-way valve allows the one on-line HPLC analyzer to monitor the eluent stream from either process column.
Figure 3 shows the two process scale columns operated in parallel mode. The on-line HPLC automatically analyzes the Column
1 eluent stream and sends the data to the DCS system where they are compared to the product purity setpoint. If only frontside
impurities are detected in the eluent stream (i.e., no product is present), the stream is automatically diverted to waste
and the two process columns continue to operate in the parallel operation mode.
Figure 3. Columns operated in parallel mode. Frontside impurities from column 1 are automatically diverted to waste.
Figure 4 shows the two process scale columns operated in series mode. The on-line HPLC automatically analyzes the Column 1
eluent stream and sends the data to the DCS system where they are compared to the product purity setpoint. At this point in
the process, the product of interest is detected in the Column 1 eluent stream, so the process valves are automatically positioned
to operate the two process columns in series, thus allowing a "heart cut" from Column 1 to be automatically charged to Column
2 for further purification.
Figure 4. Columns operated in series mode with the heart cut from column 1 are being automatically charged to column 2.