Tumble Stirring to Resoluabilize Extracts From
  Large Screening Libraries


Magnetic Tumble Stirring using the Reciprocating Tumble Stirrer (VP 709) has been demonstrated to facilitate resoluabilization of extracts dried in deep well microplates.

To test the ability of the Alligator Tumble Stirrer to resoluabilize extracts in deep well plates we added 1.75 ml of MeOH: EtOAc: Me-t-Bu ether 60:30:10 to each of the wells of a deep well microplate containing dried extracts from a large library.  The extracts were photographed via a mirror showing the bottom of the plate prior to adding the solvents (photo #1).  Next we dispensed stir discs into all the wells except E1, F1, G1, H1 and all of column 2.  (Column 1 was all the same extract so it serves as a control for stirring and not stirring. Column 2 with no stir disc serves as a partial unstirred control for the rest of the extracts.)


Photo #1- Dried Extract In Bottom Of Wells


Next we stirred the microplate at 65 tumbles per minute (high speed) and photographed the bottom of plate after 25 minutes (photo #2).  At this point all the stirred wells except C12 appeared to be totally dissolved while most of the unstirred wells still had some if not all the extracts in the bottom the well.

At this point we removed the stir discs with the VP 408AM Magnetic Replicator and loading, unloading magnetic block system (VP 770) and photographed the plate bottom (photo #3).

Next we aspirated the solvent from the plate and again photographed the empty plate bottom (photo #4).

The visual evidence indicated that the extracts in the stirred wells were dissolved in a few minutes.  Although not all the extract in the stirred well C12 was dissolved, a significant portion was by 25 minutes.  Furthermore, a target (bull's eye) like pattern was present in the bottom tip of the well with the clear areas indicating that the places where the disc had scraped the extract off the well and the colored areas indicating a depression in the wells where the disc could not physically contact the well.


Photo #2 - After 25 Minutes Of Stirring

Photo #3 - After Stir Discs Were Removed 


Column 2, which was not stirred,demonstrated 6 of 8 wells with significant dried exact still in the bottom of the well.  The 4 wells not stirred in column 1 also demonstrated significant extract in the bottom of the wells while the 4 stirred wells of the same extract were resoluabilized.

Note that this study was done before the advent of The Rotary Tumble Stirrers ( VP 710 series).  The VP 710 series stirrers are capable of tumbling the stirs at much faster speeds in the same direction (500 RPM).  We recommend the VP 710 series for stirring in deep well microplates because of the superior movement of liquids in tall columns.


Photo #4 - Extract Still In Bottom Of Wells After The Solvent Was Removed


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