Development of a combined setup for simultaneous detection of total and glycated haemoglobin content in blood samples

An original setup for analysis of glycated haemoglobin (HbA1c) in blood is reported. The construction employed a combination of the piezoelectric biosensor for glycated haemoglobin and the flow-through photometric sensor for total haemoglobin (Hb). The modification of gold electrodes with 3-aminophenylboronic acid (APBA) as a specific ligand was studied; the chemisorbed conjugate of APBA with a long-chain thiocompound provided the best affinity for HbA1c. The effect of various operating parameters, such as flow rate and instrumental setup, was optimised. The total haemoglobin content was analysed as absorbance of the haemoglobin-cyanide derivative at 540 nm. Only one standard (calibrator) diluted in various ratio was necessary for calibration and 1 microl of blood was sufficient for analysis. The full range of HbA1c content (4-15%) in blood can be analysed; the working ranges of total and glycated haemoglobin were 50-2000 and 10-90 microg/ml, respectively. The developed method was successfully evaluated on blood samples collected from diabetics.