Electrodeposition of alizarin red S on β-cyclodextrin-modified MWCNTs for the simultaneous detection of guanine and adenine in soybean

Soybean is regarded as a high-quality protein source for gout patients to replace meat products, but it is classified as medium-purine foods. This study developed the Poly-alizarin red S/β-cyclodextrin/multi-walled carbon nanotubes/indium tin oxide electrode (PARS/β-CD/MWCNTs/ITO) for the simultaneous detection of guanine (G) and adenine (A) in soybean. The electrode was fabricated via electropolymerization and characterized by SEM, TEM, FT-IR, and XRD. Cyclic voltammetry and electrochemical impedance spectroscopy confirmed its enhanced active surface area and charge transfer efficiency. The sensor demonstrated wide linear ranges of 1.0–500 μM for G and 0.1–500 μM for A, with detection limits of 0.01 μM and 0.02 μM, respectively. The peak separation between G and A was 420 mV, enabling simultaneous quantification. Applied to soybean samples, the sensor achieved recoveries of 98.6–100.2 %, validating its accuracy and potential for real-time monitoring of purine content in soybean products.