If you are not using an AQ™ nylon syringe filter, the “best practices” for using any other syringe filter is to dispose of the first few milliliters (2-3) that comes through the filter.
If there are any extractables or if there is going to be any adsorption of the sample to the membrane, it will usually happen in the first few milliliters. Passing enough sample and liquid through the filter is called bringing the filter to a “Steady State”. If you are not doing this, it may be causing your differences. If you are using the AQ nylon syringe filters, it may not be necessary to discard the first 2-3ml. due to the purity of the membrane and device.
In general, for 25mm devices you should not use the first 2-5 milliliters and for the 13 and 4mm devices, you should discard the first 0.5ml.
Click HERE for AQ™ syringe filter ordering information and pictures.
MicroSolv filters equivalency study pdf Download File