Use of a composite electrode modified with magnetic particles for electroanalysis of azo dye removed from dyed hair strands

Abstract

The analysis of dyes in hair samples can provide useful information for forensic purposes. The present work describes a novel method for the extraction of dye from a hair sample and its determination using a composite electrode to pre-concentrate carboxyl-functionalyzed magnetic nanoparticles (CFMP) employed to collect the dye in solution, hence increasing the sensitivity of the analysis. The Basic Brown 16 dye, which is widely used in temporary hair dying, was chosen as a model compound. After 15 s of reaction between 1.5 × 10 −5 mol L −1 of dye and 0.1 mg mL −1 of carboxyl-functionalyzed magnetic nanoparticles in phosphate buffer electrolyte at pH 7.0, the derivative dye was collected during 40 s at the graphite-epoxy composite electrode and then transferred to a new solution of phosphate buffer at pH 7.0. The dye presented a peak current at a potential of 0.42 V that was almost 400 times higher than without the preconcentration step, suggesting that the dye was pre-accumulated due to strong magnetic interaction with the composite electrode. Under optimized conditions, the analytical curve constructed using square wave voltammetry was linear for BB16 dye concentrations between 1.00 × 10 −7 and 1.00 × 10 −6 mol L −1. The limits of detection and quantification were 1.01 × 10 −8 and 2.37 × 10 −8 mol L −1 , respectively. The proposed method was successfully applied in the determination of BB16 dye extracted from a dyed hair strand sample by alkaline digestion.

Advances and Trends in Voltammetric Analysis of Dyes

“…The method was applied in samples of commercial dyes with a recovery from 98.40 to 103.8% and relative standard deviation of less than 1.51%. Corrêa et al [70] used a composite electrode to preconcentrate carboxylfunctionalized magnetic nanoparticles for the determination and quantification of the Basic Brown 16. In this case, the determination of dye was made by the signal referring to the oxidation of the -OH group, which allowed a linear relationship between 1.00 · 10 À7 and 1.00 · 10 À6 mol L À1 with limits of detection and quantification of 1.01 · 10 À8 and 2.37 · 10 À8 mol L…”