All nylon membranes carry some positive charge, some much more than others.
The AQ™ brand of nylon syringe filters are manufactured with membranes that have highly reduced positive charge. This low charge amount brings a value to dissolution testing or HPLC filtering as the excess positive charge on membranes will adsorb negatively charged analytes and can change the accuracy of your results and that should be minimized or eliminated as a best practice.
NOTE: Since syringe filters should not alter your chromatography or dissolution results at all, any filter that removes anything other than un-dissolved particles is interfering with good laboratory practices and puts your results at risk, especially when the membranes are not made with minimized charge.
Click HERE for ordering information and pictures of AQ™ brand of syringe filters.