Does the filter plate drip length Matter? To answer this question—and to find which length is best suited for your needs—it’s important to understand the three general methods that are employed for filtration using microplates.
- Centrifugation protocols have the filter plate stacked directly on top of a receiver plate within a swinging bucket rotor. There are several considerations for a successful experiment:
- The two plates must mate adequately to survive the process.
- The receiver plate should be supported to withstand the necessary centrifugal force.
- The stack of plates must clear the rotor arms as the bucket extends.
- The filter plate drip should not extend below the expected fill level of the receiver plate.
Typically, filter plates with relatively short drips are utilized in centrifugation protocols because the stacked plates position the drip within the receiver plate, minimizing cross contamination while maximizing sample size.
- Positive pressure manifolds also employ direct stacking of the filter plate above the receiver plate. Gas pressure is applied to the top of individually-sealed wells of the filter plate to force the liquid into the receiver. Considerations for the drip length are the same as with centrifugation.
- Vacuum filtration places a seal between the filter plate resting on top of the seal and the receiver plate, which rests within the vacuum chamber of a manifold device. Differing manufacturers of vacuum manifolds have differing thicknesses of their seals and in the heights of the vacuum chamber walls. In order to avoid cross contaminations, these variations require some attention to how well the filter plate drip is positioned relative to the receiver well. Some adjustment can be effected by elevating the height of the receiver plate within the vacuum chamber by means of a support spacer to a position closer to the filter plate drips. Because of the thickness of the gaskets, longer drip lengths and/or shorter filter plate skirt walls are employed to position the drips to a lower position within the vacuum chamber.