For validation under point-of-use conditions, we determined the glucose concentration in a human blood sample using the internal standard addition method with the GOx-based sensors and the integrated AOx-based O2-scavenger (Figure ). The blood was tested without any treatment except for the addition of specific glucose concentrations (5 to 10 mM) as internal standards. Due to the presence of chloride ions in the sample matrix (blood), which shift the potential of the pseudo-reference electrode of the screen-printed electrodes, we applied a higher potential (0.6 V vs pseudo RE) compared to the measurements conducted in buffer .