Work

Colorimetric measurement of copper(II) in sand using direct electrokinetic extraction into a polymer inclusion membrane

Year: 2025

Type: article

Abstract: BACKGROUND: to digest and extract the heavy metals in solid soil matrix into a liquid matrix. This not only lengthens the analysis process but also reduces the feasibility of in-field analysis because of the use of hazardous chemicals. Alternative approaches that are low-cost and environmentally friendly, while also allowing in-field analysis with minimal skill requirements need to be developed for better screening and monitoring purposes. RESULTS: An electrokinetic extraction system was developed for the direct quantification of Cu(II) in silica sand and tailings samples using a colorimetric polymer inclusion membrane (PIM). Using an electric field, heavy metals are mobilised from the silica sand and move into the PIM where they complex with the colorimetric reagent, 1-(2-pyridylazo)-2-naphthol (PAN), causing a colour change proportional to the Cu(II) concentration. This was explored with Cu(II) spiked into silica sand, whereby a linear detection range of 0.30 μg-2.35 μg of Cu(II) (equivalent to 1.20-9.40 μg of Cu(II) per gram of sand) was achieved. SIGNIFICANCE: This is the first demonstration of electrokinetic extraction of ions from a solid material and shows potential for minimising sample pretreatment processes for in-field chemical analysis. The system is small in size and dry-to-touch and enables quantification using a low sample volume while remaining easily portable. Quantification through image analysis reduces the requirement for specialised skills.

Source: Analytica Chimica Acta

DOI: 10.1016/j.aca.2025.344262