Millipore DDHW00010-WW, Руководство пользователя

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Direct Detect® Spectrometer User Guide 12
9
Direct Detect® Assay-free Card and Sample Preparation
9.1 Direct Detect® Assay-free Card
All concentration measurements are performed using the Assay-free card.
Figure 7. Direct Detect® Assay-free card
The card contains four hydrophilic polytetrafluoroethylene (PTFE) membrane positions,
sized for easy sample application and surrounded by a hydrophobic ring that retains the
sample to be analyzed within the IR beam. A 2 µL sample volume is recommended in order
to assure proper sample application, drying, and measurement.
By design, the positions on the card are numbered from 1 to 4, starting from the bottom.
Position 1, by software default, is reserved for the “blank” measurement. The “blank” is the
buffer/solvent used to resuspend the sample, but contains no protein or lipid/detergent.
One or more of the remaining card positions are used for the protein and/or lipid/detergent
samples.
The Assay-free card can be inserted into the system and analyzed immediately after
preparation. The Direct Detect® spectrometer has a built-in drying system that
automatically dries the sample to the point where it gives an accurate reading. The first
sample position typically takes the longest period of time to dry, with subsequent positions
taking less time. Including drying time, the total measurement time for a card loaded with
2 µL samples does not exceed 5 minutes.
The Direct Detect® Assay-free card is intended for one-time protein and/or lipid/detergent
spotting. However, already prepared cards can be stored and read again.