Chemisorbed palladium phthalocyanine for simultaneous determination of biomolecules

Abstract In this study, the palladium(II) tetraaminophthalocyanine (PdTAPc) was synthesized and characterized with different analytical techniques to confirm its purity. The synthesized PdTAPc was immobilized on the electrode surface through self-assembled monolayer (SAM) technique. The immobilized PdTAPc on glassy carbon electrode (GCE) was characterized by XPS, Raman spectroscopy and cyclic voltammetry. The Raman spectra and XPS indicated the modification of the electrode surface with the PdTAPc film (GCE/PdTAPc) by chemisorption. The chemisorbed electrode slightly blocked the charge transfer of K 4 Fe(CN) 6 redox probe. The electroactive species PdTAPc on the electrode surface was used for the sensing of ascorbic acid in the concentration range of 1–25 μmol L −1 and the peak current as well as sensitivity of ascorbic acid species was enhanced by using MWCNTs decorated on the PdTAPc modified GCE (GCE/MWCNTs/PdTAPc). The MWCNTs dispersed PdTAPc modified electrode was used for the simultaneous determination of ascorbic acid (AA) in the concentration range 3–24 μmol L −1 , dopamine (DA) 2–16 μmol L −1 and uric acid (UA) 5–40 μmol L −1 respectively and the peaks were clearly separated without any overlapping from one another. The correlation coefficient ( r ) was found to be 0.9910, 0.9893 and 0.9982 with a limit of detection (LOD) 1.0, 0.60 and 1.50 μmol L −1 (S/N = 3) respectively for AA, DA and UA biomolecules. The sensitivity for the simultaneous determination of the biomolecules with MWCNTs modified electrode was high and can be determined without any interference. The sensitivity was found to be 1.0149, 1.9303 and 0.4328 mA μmol −1  cm −2 respectively for AA, DA and UA compounds. The modified electrode was also successfully applied to the determination of AA, DA and UA in urine samples.