In the analytical scenario, it is important to identify as many constituents of a sample as possible and/or to determine their concentration, whereas in the preparative case often only one or a few products with a specific purity requirement needs to be obtained.
To use the highest possible injection volume and to achieve low solvent consumption is important in preparative work.
|Parameters||Analytical HPLC||Preparative HPLC|
|Separation goal:||as many peaks as possible, baseline-separated||just interested in the desired product peak|
|Sample volume:||as little as possible (1 to 20 µl per injection)||as much as possible without peak overlap > 20 µl|
|Column inner diameter:||1 to 4 mm||> 4 mm|
|Particle size:||< 5 µm||> 5 µm|
|Flow rate:||1.0 ml/min||5 to 5000 ml/min|
|Detection:||as sensititve as possible||monitoring, saturation can be problematic|
|Peak shape:||Gauß shape for analyzability||no matter, as long as product peak is clean|
|Fraction collection:||no||yes (automatized)|
|Solvent recovery:||no||desirable, recycling|
|Gradient:||optimizes separation and speed||interferes with solvent recycling|
What kind of devices are required?
Your HPLC system will need a collection device for the eluting peaks. This can be a fraction collector to fractionate the entire run or a cost-effective multi-port multi-position switching valve with typically 6 to 16 switch positions. If you plan the number of required valve positions for peak fractions, reserve at least one for solvent recycling and one for waste. Better, but also more expensive, is an additional diverter valve.
Enter HPLC purification ...
The AZURA® Prep Compact system offers the perfect introduction to semi-preparative HPLC. With an isocratic pump for maximium flow rates of up to 50 ml/min and manual injection, up to several hundred milligrams of sample can be cleaned per run. The system contains a variable wavelength UV detector. The collection of fractions is triggered by the detector signal via a 12-port multi-position valve. Like all other components, it is controlled by the easy-to-use PurityChrom® software.
- Very compact, several systems can be stacked
- Variable wavelength UV detector
Other detectors such as RI or MS can be combined.