Catalytic resonance scattering spectral determination of ultratrace horseradish peroxidase using rhodamine S

A highly sensitive and selective resonance scattering spectral assay was proposed for the determination of horseradish peroxidase (HRP), based on its catalytic effect on the H 2 O 2 oxidation of KI to form I 3 − . The I 3 − combined respectively with rhodamine (Rh) dye such as rhodamine S (RhS), rhodamine 6G (Rh6G), rhodamine B (RhB) and butyl‐rhodamine B (b‐RhB), to form association particles (Rh‐I 3 ) n . The four Rh systems all exhibit a stronger resonance scattering (RS) peak at 424 nm. For the RhS, Rh6G, RhB and b‐RhB systems, HRP concentration in the range of 3.2 × 10 −12 to 4.8 × 10 −9 , 2 × 10 −11 to 3.2 × 10 −9 , 1.6 × 10 −11 to 3.2 × 10 −9 and 1.6 × 10 −11 to 4 × 10 −9  g/mL was linear to its RS intensity at 424 nm, with a detection limit of 2.2 × 10 −12 , 2.5 × 10 −12 , 4.4 × 10 −12 and 2.6 × 10 −12  g/mL, respectively. This RhS system was most sensitive and stable, and was applied for the determination of HRP in the hepatitis B surface antibody labeling HRP and water samples, with satisfactory results. Copyright © 2009 John Wiley & Sons, Ltd.