Electrochemical determination of caffeine in the presence of paracetamol using a self-assembled monolayer of non-peripheral amine substituted copper(II) phthalocyanine

This article reports the electrochemical determination of caffeine in the presence of paracetamol (PA) using a self-assembled monolayer (SAM) of non-peripheral amine substituted copper(II) phthalocyanine (4α-CuIITAPc) on glassy carbon electrode (GCE). The 4α-CuIITAPc SAM modified GCE shows two pairs of redox waves at 0.16 V and 0.23 V, corresponding to CuII/CuI and Pc−1/Pc−2, respectively. The 4α-CuIITAPc SAM modified GCE exhibits an excellent electrocatalytic activity toward caffeine. Further, it was successively used for the selective and simultaneous determination of caffeine in the presence of PA. The differential pulse voltammetric current responses of caffeine were increased linearly while increasing the concentration of caffeine in the range of 0.005–1.4 mM and a detection limit was found to be 3.04 × 10−8 M (S/N = 3). Further, the modified electrode successfully recovers caffeine in blood serum samples. The present method was also applied for the determination of caffeine in cola drinks and simultaneous determination of caffeine and PA in pharmaceutical formulations. The results obtained from the present method were validated with the HPLC method.

► The SAM of 4α-CuIITAPc was used for the determination of caffeine.
► Simultaneous determination of caffeine and paracetamol was achieved.
► A detection limit of 3.04 × 10−8 M (S/N = 3) caffeine was obtained.
► The proposed method was successfully applied to real samples.