Performance enhancement in flow reversal flow injection using on-capillary detection Original Research Article

On-capillary absorbance detection is combined with flow reversal flow injection for automated determinations of glucose. The flow injection system used fused silica capillary tubing of 75 μm i.d. as the reactor tubing and a six-port injection valve to enable the sample zones to make multiple passes through a UV–Vis absorbance detector. Phenol red was used as the sample to characterize the amount of zone broadening due to the flow reversals. Results from a single zone making five passes by the detector showed a decrease in peak absorbance of only 6.1%, while the peak width (measured at half-height) increased by only 5.6%. This system was also applied to an enzyme-catalyzed kinetic determination of glucose where a calibration curve and a sample determination was performed in less than 6 min while the combined consumption of standard and sample was 300 nl.