Automation of solid phase extraction

Plants are a rich source of active pharmaceutical ingredients (APIs). Their qualitative and quantitative characterisations are difficult tasks for every analytical scientist due to the complexity of the samples and their concentrations which often occur in very small amount. As a result, sample concentration and purification are crucial steps for structure elucidation and quantification. The most common way to achieve this, is solid phase extraction (SPE) next to liquid liquid extraction (LLE). A broad range of SPE materials exists, either based on silica or on polymeric particles with different surface modifications [1]. A major drawback of these methods is time consuming sample preparations which have to be done manually under light. Additional biases are occurring due to the manual handling causing difficulties in reproducibility and an increase in standard deviation of quantitative results. To overcome these problems a Phynexus (San Jose, CA) MEA^TM Personal Purification System was adapted for the automation of sample preparation. This system contains an automated 12-channel pipette and allows to condition, equilibrate, load, wash and elute in one go. Additionally the robotic system offers a range of flow rates that maximizes the purification and enrichment efficiency. Different SPE materials, e.g. NP-silica, C-18 silica, cellulose beads, were filled in 1.2ml tips and sealed with frits on both sides. The automation showed to be a reliable and a repeatable tool for extraction and purification.

References: 1. Vallant, R.M. et al. (2007) Anal. Chem. 79:8144–8153.