While running according to the instructions, I noted the currents were a little high at low pH. Would this be remedied by using a 50 um capillary?
[top] Yes, for the low pH phosphate buffers the currents are quite high under the operating conditions (15 kV, 300 V/cm). However, we prefer the 75 um i.d. capillaries for the pKa application for a couple of reasons. One, they are easier to work with and are less prone to plugging. Most importantly, we need to maximize the detection sensitivity as much as we can in order to analyze low solubility compounds. The lower concentration we can detect, the more dilute we can prepare the low solubility compounds and analyze them without precipitation in the capillary. This is a very important issue for many labs working with low solubility, high log P compounds.
