# Novel Composite Electrode Based on Graphite and Polyurethane without Isocyanates for Electroanalysis with Modulated pH Sensitivity

## TL;DR

A new eco-friendly composite electrode made from graphite and a sustainable polymer was developed for pH-sensitive electroanalysis.

## Contribution

The novel composite uses a poly(hydroxyurethane) matrix derived from carbonated macaw palm oil and 1,6-hexanediamine, avoiding isocyanates.

## Key findings

- The composite electrode showed sensitivity to pH changes and detected anionic and cationic species.
- It achieved a detection limit of 1.17 × 10–7 mol L–1 for sildenafil citrate in phosphate buffer and synthetic urine.
- The electrode demonstrated 100 ± 1% recovery in synthetic urine, indicating high accuracy.

## Abstract

A composite was developed to align with the principles
of green
chemistry and the sustainable development goals, with a focus on its
renewability, production, and degradation. Thus, a polymeric matrix-agglutinant,
poly­(hydroxyurethane), was synthesized from carbonated macaw palm
oil (derived from epoxidized oil and CO2) and 1,6-hexanediamine.
When combined with graphite, this material resulted in a solid composite
exhibiting uniform graphite dispersion and moderate hydrophobicity,
contributing to its applicability as an electrode material. The composite
electrode demonstrated sensitivity to pH variations, enabling its
application as a probe for both anionic (K3[Fe­(CN)6]) and cationic ([Ru­(NH3)6]­Cl3) species. Its analytical performance was evaluated in the determination
of sildenafil citrate (SIL) in phosphate buffer solutions at various
pH values and in synthetic urine. The electrode exhibited a sensitive
response for SIL detection, with a limit of detection (LOD) of 1.17
× 10–7 mol L–1, limit of
quantification (LOQ) of 3.90 × 10–7 mol L–1, sensitivity of 0.1873 μA μmol L–1, and a recovery of 100 ± 1% in synthetic urine.