FAQ

Impact FAQs

Q. Does the order of addition, sample first or solvent first, matter?

A. The order of addition does not matter as long as mixing is thorough. However, adding solvent after sample can lead to more rapid mixing as the dispense volume is much larger.

Q. What is the best technique for addition for solvent to plasma (or plasma to solvent)?

A. The best results are achieved with direct addition of the solvent to plasma (or plasma to solvent) because this will achieve more efficient mixing. Refrain from placing the pipette tip on the side of the well when dispensing the second addition.

Q. What conditions may require increased filtration force?

A. Impact was designed with versatility in mind incorporating a depth filtering system in order to handle tougher precipitate. Impact is approved for use for all of the following, but please keep in mind adjustments may need to be made to obtain complete filtration. These conditions include:

1. Using methanol as the precipitation reagent; methanol forms smaller precipitates than acetonitrile which can potentially reduce flow through the Impact filters.
2. When processing tissue homogenates; homogenates, by nature, have more particulate which can potentially reduce flow through the Impact filters.
3. When processing larger volumes of plasma (>200 µL); larger amounts of plasma mean more particulate which can potentially reduce flow through the Impact filters.

Q. What solvents are compatible with Impact?

A. Acetonitrile and methanol are both compatible with the Impact plate.

Q. How much sample can I process?

A. The total volume of sample and precipitation solvent should not exceed 1.60 mL. Example: At a ratio of 1:3, 400 µL of plasma can be processed with 1200 µL of acetonitrile, for a total volume of 1.60 mL.

Q. What equipment should I use for mixing?

A. Thorough mixing is the key criteria for success, so any equipment that mixes well can be used. A vortex set to a speed that does not splash sample into adjacent wells is very effective. Another option is to use a pipette to mix by aspiration.

Q. Can Impact be automated?

A. Yes, automated liquid handlers fitted with a vacuum filtration system can make the precipitation process with Impact even quicker. The Impact 96-well plate format conforms to SBS standard dimensions.

Q. Can I use a partial plate of Impact?

A. Absolutely. If vacuum is being used to process the samples, please use a sealing mat or sealing tape to cover un-used wells, this will keep vacuum pressure high enough to filter the sample through the filters of the plate.