Abstract: Devices and methods for tuning biofluid sample pH to enable more accurate analyte concentration measurements with pH-sensitive biosensors. In the embodiments, biofluid samples react with a polymer buffering material during transfer to a sensing element. The reaction with the buffering material causes protonation or deprotonation of the sample based upon 1) the pH of the sample, and 2) the selected quantity and pKa of the functional groups in the buffering material. Controlling the H+ content of a biofluid sample has beneficial effects on the accuracy of the biosensor by reducing or eliminating signal changes due to redox moiety variability, thereby isolating signal changes reflecting analyte concentration.