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| Semipreparative Columns |
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The YMC Scale-Up is defined by 4 steps:
1. Analytical Scale: Method Development Determine separation conditions by using analytical columns packed with different stationary phases and various conditions.
2. Study the preparative scale. Select the particle size of the packing material and the inner diameter of column appropriate for the sample volume.
3. Optimise the separation conditions and perform loadability studies using analytical columns with inner diameter of 4.6 mm or 6.0 mm packed with the packing material selected for the preparative separation (scout column). If the particle size of the packing material is the same as in the Step 1, this process can be omitted. If the preparative column is more than 100 mm i.d., it is advisable to insert another step with a scout column of 20 mm i.d. in order to accurately predict loadability and calculate the running costs.
4. Proceed with the preparative separation with scale-up of chromatographic parameters such as flow rate/ column ID/ sample load as necessary.
From all the given steps above the most demanding step will be the scale-up of the chromatographic parameters in order to meet the preparative demands.
There are a number of scalable parameters: flow rate, column i.d., sample load, tubing i.d., sample injection concentration, volume of sample loop, consumption of solvent, dead volume,fraction mass, size of the detector cell.
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Scale-Up-factor
In order to simplify your Scale-Up the three most important scale-up factors are summarised.
Scalable factor SF |
i.d. “Linear Scale-Up” |
Column length |
Column length and i.d. “Volume” |
SF = r2
ID, prep / r2
ID, anal. |
SF = lID, prep / lID, anal. |
SF = (r2ID, prep / r2 ID, anal.) / (lID, prep / lID, anal.) |
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Impact |
Flow rate Eluent composition |
Retention time Cycle time Plate number |
Amount of adsorbent |
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Linear Scale-Up
In most cases it is beneficial to develop a semi-preparative method on an analytical scale column.
The analytical separation carried out on a 150 x 4.6 mm i.d. column has to be scaled up to 150 x 20 mm i.d. Therefore the chromatographic parameters such as flow rate and column load have to be adjusted according to the following equation:
Linear Scale-UP
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Guideline for Sample Load according to column i.d.
Column i.d. (mm) |
Scale-Up factor |
Loadability (mg) |
4.6 |
1 |
1-4 |
10 |
4.7 |
5-20 |
20 |
18.9 |
20-80 |
50 |
118 |
80-350 |
75 |
266 |
270-980 |
100 |
472 |
470-1900 |
150 |
1060 |
1000-4200 |
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