# Electrochemical Sensor Based on a Composite of Babassu Starch, Carbon Black, and Cobalt Phthalocyanine for the Detection of Hydroxychloroquine

## TL;DR

A new electrochemical sensor made from Babassu starch, carbon black, and cobalt phthalocyanine effectively detects hydroxychloroquine in environmental and pharmaceutical samples.

## Contribution

The paper introduces a sustainable, starch-based composite sensor for hydroxychloroquine detection with high accuracy and stability.

## Key findings

- The sensor achieved a detection limit of 0.015 μmol L–1 for hydroxychloroquine.
- Recovery studies showed 100–105% accuracy in pharmaceutical and water samples.
- The modified electrode remained stable without fouling after repeated use.

## Abstract

This work presents the development of an electrochemical
sensor
based on a starch film extracted from the Babassu coconut mesocarp
flour, carbon black (CB), and cobalt phthalocyanine. Scanning-electron
microscopy coupled with energy-dispersive spectroscopy confirmed the
presence of each component in composite, by confirming alteration
of surface morphology and composition. Raman and Fourier-transform
infrared spectroscopy also evidenced surface alteration while atomic-force
microscopy revealed increase in rugosity after insertion of CB and
cobalt phthalocyanine. The developed sensor was applied for the determination
of hydroxychloroquine (HCQ) in both environmental and pharmaceutical
(tablet) samples, using linear sweep voltammetry and a 0.1 mol L–1 phosphate buffer solution (pH = 7.0) as the supporting
electrolyte. The method achieved impressive detectability in comparison
with literature, with limits of detection (LOD) and quantification
(LOQ) of 0.015 μmol L–1 and 0.052 μmol
L–1, respectively. Recovery studies conducted in
pharmaceutical matrices, tap water, and treated water samples yielded
values ranging from 100% to 105%, demonstrating the sensor’s
accuracy. Notably, no electrode fouling was observed after HCQ oxidation,
confirming the stability of the modified electrode. These findings
underscore the potential of this sensor for environmental monitoring
and highlight starch as a sustainable alternative material for immobilizing
modifiers on electrodes.