Portable dual-channel liquid chromatography system with versatile elution for the rapid detection of glycated hemoglobin and bilirubin

In this study, we present a portable dual-channel liquid chromatography (PDCLC) system designed for rapid and efficient analysis of trace analytes. This compact analytical device, with a size of approximately 290 × 290 × 180 mm³, weighs ∼3.5 kg and supports both isocratic and gradient elution modes with an ultra-low injection volume of just 0.72 µL. The PDCLC system consists of three core units: microsyringe pumps, a chromatographic microchip, and a dual-channel absorbance detector. The developed microsyringe pump can control a stable flow rate gradient change as low as 167 nL/min. There are ion-exchange and reverse-phase dual chromatographic columns in the integrated microchip. This enables the developed microchip to have the ability to separate multiple substrates, compared with microchips with a single ion-exchange column or reversed-phase column, significantly reducing the cost of detection and preparatory work, and are particularly suitable for portable detection. For detection, the dual-channel absorbance detector uses removable LED light sources for portability and multi-analyte compatibility. An optimized stray light shielding mechanism enhances sensitivity for reliable analytical performance. Based on the above core units, the system constructed can perform the analysis of glycated hemoglobin and unconjugated bilirubin without replacing the microchips, and the analysis is successfully conducted within 3 min and 5 min for glycated hemoglobin and unconjugated bilirubin, respectively, in the gradient and isocratic modes, with repeatability less than 2.6 % and 2.9 %. These results highlight the potential of the PDCLC system in rapidly and reliably analyzing biomarkers for early disease diagnosis.