Figure 3: The dissolved oxygen content of phosphate buffer (pH 7.0) after each successive addition of various volumes of 0.50 M glucose standard: (0) 0.0, (1-3) 1.0 and (4) 2.0 μL. The inset displays the linear calibration curve for glucose from 0.00 to 0.60 mM. Error bars are 95% confidence intervals calculated from three replicate measurements.