To increase throughput in preparative HPLC, it is necessary to load high amounts of sample onto the column. This application note describes two common techniques - sandwich injection and organic-phase injection, and how they can be performed easily on an Agilent 1100 Series purification system.
To increase throughput in preparative HPLC, it is necessary to load high amounts of sample onto the column. Since compounds must be applied at much higher concentrations than in analytical HPLC, a modified injection principle is required to avoid precipitation and clogging of the flow path.
The document details two common techniques: sandwich injection and organic-phase injection. Sandwich injection involves placing the sample between two plugs of sample solvent, which can be performed easily using an injector program in Agilent ChemStation without hardware re-configuration. Organic-phase injection requires re-plumbing the preparative pumps and injector to connect the autosampler into the flow path right after the pump delivering the organic solvent, ensuring the sample only contacts the organic phase until it reaches the mixing tee.
The document describes sandwich injection and organic-phase injection as two common techniques to avoid precipitation and clogging.
Yes, sandwich injection can be done on a standard system using an injector program in Agilent ChemStation.
Organic-phase injection requires re-plumbing of the preparative pumps and the injector, making it impossible to perform both methods on the same system without changes.