# Cost-Effective Voltammetric Determination of Salicylic Acid in Milk Using Copper Wire Electrodes

## TL;DR

This paper introduces a low-cost, eco-friendly method to detect salicylic acid in milk using copper wire electrodes and simple chemical treatments.

## Contribution

A novel, sustainable voltammetric method using Cu/CuO electrodes and a solvent-free sample pretreatment for salicylic acid detection in milk.

## Key findings

- The Cu/CuO electrode enhanced the voltammetric response and provided antifouling properties.
- The method achieved a linear range of 10–500 μmol L–1 and a detection limit of 3.0 μmol L–1.
- Recovery percentages in spiked milk samples ranged from 91% to 107%, showing high accuracy.

## Abstract

The illegal use of
salicylic acid (SA) as a milk preservative
raises
significant health concerns, highlighting the need for accurate analytical
methods capable of detecting this adulteration. This study presents
an innovative, ecofriendly voltammetric method for SA determination
in milk. The proposed method employs a working electrode fabricated
from inexpensive, commercially available Cu wires, which were chemically
modified with a CuO-rich layer grown electrochemically via cyclic
voltammetry in alkaline medium (0.1 mol L–1 NaOH).
This modifying layer not only enhanced the voltammetric response of
SA but also conferred antifouling properties to the working electrode.
Differential pulse voltammetry, under optimized conditions, yielded
a linear range of 10–500 μmol L–1 with
a limit of detection of 3.0 μmol L–1. A key
innovation is a simple and rapid sample pretreatment using aqueous
solutions of ZnSO4 and NaOH. The ZnSO4 precipitates
proteins, while NaOH ionizes SA, facilitating its extraction into
the aqueous phase. This procedure minimizes sample and reagent consumption,
eliminates organic solvents, and allows the processing of up to eight
samples in 15 min. This environmentally friendly pretreatment, combined
with the Cu/CuO electrode, enabled reliable SA quantification in spiked
milk samples, with recovery percentages ranging from 91% to 107%.
This approach offers a cost-effective, sensitive, selective, and more
sustainable method for SA quantification in milk.