Membrane filters can bind some substances. The amount of loss depends on how much of the substance is passed through the membrane, because the number of binding sites is limited and can be saturated. To minimize loss of anything that sticks to the filter, minimize the diameter of the filter and maximize the volume and concentration of the solution passed through it. The material of which the membrane is made can also affect the amount of binding. PTFE (that is, Teflon) filters will probably minimize losses due to binding.