Insights into the ninhydrin chemiluminescent reaction and its potential for micromolar determination of human serum albumin

The N-terminal region of human serum albumin (HSA) has an inherent affinity for Co(II) ions. On this basis a new continuous flow method for detection of HSA has been developed taking advantage of the strong quenching effect of the albumin in the ninhydrin-H₂O₂-Co(II) chemiluminescent system. The analytical potential of the system is compared with other conventional chemiluminescent reagents. The method gives linear responses from the detection limit (0.30 μM HSA) up to 6.8 μM. The repeatability of the method is good (RSD=7%), it is cheap and rapid to apply and does not require the use of insoluble or expensive reagents nor sophisticated equipment.