When we remove concentration points that correspond to sub-200 µL dispensed volume of analyte, our standard deviation improves from ± 2 × 10 -6 cm 2 /s to ± 1 × 10 -6 cm 2 /s. Based on this observation, we use 200 µL as the minimum dispensing volume for the following experiment, where we perform titration experiments with 200 µL aliquots.