Automated purification

Automated purification systems should have the capacity to take a crude sample or prefractionated extract through to a series of pure compounds with limited human input. A number of companies produce automated purification systems. Automated purification of a target compound can be configured quite readily on many instruments using, for example, a UV, MS, or evaporative light scattering (ELS) signal. 

---

Lin, C.T., Moore, P.A., Auberry, D.L. et al. (2006) Automated purification of recombinant proteins combining high-throughput with high yield. Protein Expression and Purification, 47 (1), 16-24. 

Automation of the strategies described above can be achieved using instruments supplied by GE Healthcare. Many of the procedures described above are preprogrammed to allow ease of implementation of HTP automated purification techniques. 

Another challenge in ATRP is to remove the catalyst prior to the analysis of the polymers. In the case of automated sample withdrawing, this leads to the necessity of an automated purification system. For this purpose, an SPE unit was utilized... 

Integration of automated amide synthesis with automated purification has been implemented by workers at Bristol-Myers Squibb [89] using a Zymark robotic system. 

Each of the library steps required a work-up followed, by chromatographic purification. While this was feasible for the 16 pools 4-19 prepared, larger monomer sets or intermediate splitting in pools with more reactions to be handled would definitely require automated purification/work-up procedures. 

The radical cascade synthesis was applied to the preparation of drugs such as irinotecan [62], and drug candidates such as lurtotecan [66], silatecan DB-67 [67] and homosilatecans [68]. Moreover, a convergent synthesis could be applied to a combinatorial synthesis, in which over one hundred homosilatecans were prepared by parallel synthesis and automated purification [69]. 

These libraries contain a relatively small number of individuals (typically tens to hundreds) and are almost always prepared as discrete libraries using parallel synthesis and automated or semiautomated devices. Focused libraries are predominantly prepared in solution because of the easier shift from classical organic synthesis to solution-phase combinatorial chemistry, while automated purification procedures for relatively small arrays of discrete compounds in solution are common nowadays. The... 

M4, 22 amines), and after the reaction the cleavage solutions were recovered by filtration into 96 corresponding microtiter plates to give crude L3 as 8448 spatially separated crude benzopyrans that were submitted to an automated purification procedure (step f) (115) and concentrated using commercially available vacuum centrifuges to give the final pure library (Fig. 6.15). 

Simultaneous handling of multiple reactions make simple automated purification protocols extremely important when large libraries are being considered. 

In this example the open-access system was used to determine the success of the reactions and generate a purity profile before performing automated purification u.sing HPLC (Autoprep — see Chapter 8) on the now characterised crude samples. 

J.P. Kiplinger, R.O. Cole, S. Robinson, E.J. Roskamp, R.S. Ware, H.J. O Connell, A. Brailsford, J. Batt, Structure-controlled automated purification of parallel synthesis products in drug discovery. Rapid Commun. Mass Spectrom., 12 (1998) 658. 

Products/technologies Products include automated purification and analysis systems for combinatorial chromatography, including its high-throughput Combinatorial Chromatography System for HPLC purification and analysis. Additional product offerings are the UniPoint System software automated... 

Solid-phase parallel synthesis mimics the previously described solution phase strategy. This approach easily lends itself to both semi- and full automation. In contrast to the solution phase method, purification is easily achieved by simply washing the resin beads, and the reactions can be driven to completion by excess reagents, multiple cycles, and microwave techniques. The initial building block or scaffold is attached to the resin bead by a detachable linker. At the end of the synthesis, the final construct is released under the appropriate cleavage conditions for automated purification, usually by high-pressure liquid chromatography (HPLC). This allows bioanalysis of the final product in aqueous solution under standard assay conditions. 

Routburg, M. Swenson, R. Schmitt, B. Washington, A. Mueller, S. Hochlowski, J. Maslana, G. Minn, B. Matuszak, K. Searle, P. Pan, J. Implementation of an Automated Purification/Verification System, presented at The International Symposium on Laboratory Automation and Robotics, Boston, MA, October, 1996. 

H.J. Brailsford, A. Batt, J. Structure-controlled Automated Purification of Parallel Synthesis Products in Drug Discovery, Rapid Commun. Mass Spectrom. 12, 658-664 (1998). 

The procedure for extraction of catecholamines with activated alumina was developed by Anton and Sayre, and has subsequently been used in a number of studies. Alumina extraction has not been popular, although automated purification with alumina microcolumns was studied closely by Tsuchiya et al. The sample preparation scheme includes increasing the pH of the alumina to >8.5 and vigorous shaking of the sample with the alumina, resulting in adsorption of the catecholamines by attraction of the hydroxyl groups of the catechol nucleus. The alumina can then be washed with water or buffer, and finally the catecholamines are eluted with acid, such as 0.3 m acetic acid. Since catecholamines are... 

As has been mentioned above, there are principally no constraints in terms of reaction conditions in solution-phase combinatorial chemistry. However, the necessity to obtain sufficiently pure products may limit the types of reactions that are suitable for this purpose. These limitations may decrease with the advent of automated purification techniques, particularly those based on chromatography coupled with analytical tools such as mass spectrometry. 

---