Determination of guanine and adenine by high-performance liquid chromatography with a self-fabricated wall-jet/thin-layer electrochemical detector at a glassy carbon electrode

• A wall-jet/thin-layer amperometric ECD coupled to HPLC.
• High analytical performance for trace analysis of purine bases.
• Negative effects of competitive electrode adsorption of purine bases on their conventional electroanalysis.
• Favorable insensitivity of HPLC-ECD to their electrode-adsorption.

A sensitive wall-jet/thin-layer amperometric electrochemical detector (ECD) coupled to high-performance liquid chromatography (HPLC) was developed for simultaneous determination of guanine (G) and adenine (A). The analytes were detected at a glassy carbon electrode (GCE) and the HPLC−ECD calibration curves showed good linearity (R2>0.997) under optimized conditions. Limits of detection for G and A are 0.6 nM and 1.4 nM (S/N=3), respectively, which are lower than those obtained with an UV–vis detector and a commercial electrochemical detector. We have successfully applied this HPLC−ECD to assess the contents of G and A in hydrochloric acid-digested calf thymus double-stranded DNA. In addition, we compared in detail the analysis of G and A by cyclic voltammetry (CV) and by the HPLC−ECD system on both bare GCE and electroreduced graphene oxide (ERGO) modified GCE. We found that the adsorption of G and A on the electrode surfaces can vary their anodic CV peaks and the competitive adsorption of G and A on the limited sites of the electrode surfaces can cause crosstalk effects on their anodic CV peak signals, but the HPLC−ECD system is insensitive to such electrode-adsorption and can give more reliable analytical results.

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