Varnish polish functionalized paper as a new solid platform for colorimetric determination of copper (II) in water

ABSTRACT

In the current strategy, a highly sensitive and fast one-step colorimetric assay for trace determination of Cu²⁺ in water is presented. The planned assay was based upon the use of varnish polish-modified filter paper printed with 2-[5-(2-hydroxy-5-sulfophenyl)-3-phenyl-1-formazyl] benzoic acid monosodium salt, commercially named zincon. Under optimal conditions, the designed assay readily recognised the formation of blue–purple-coloured Cu–ZI chelate in less than 10 min. The proposed probe was able to detect Cu²⁺ in the concentration range from 0.04 to 10 μg/mL (6.34 × 10⁻¹ to 1.59 × 10³µM), with low limit of detection (LOD) of 0.01 μg/mL (1.59 × 10⁻¹ µM). The LOD was 10-fold lower than the allowable level for Cu²⁺ in drinking water set by WHO legislation. The assay was applied for Cu²⁺determination in water with acceptable recoveries (89.6–102.1%) and precision (<3%). Therefore, the proposed sensing assay might be considered as a potential rapid and low-cost candidate for total determination and speciation of Cu²⁺in water samples.

KEYWORDS:

• Colorimetric one-step assay
• copper(II) determination
• hydrophobic surface
• varnish polish functionalised filter
• water samples

Acknowledgements

The authors thank the kind contribution and support received from Prof Iqbal M. Ismail for the facilities provided during this study from the Center of Excellence in Environmental Studies, King Abdulaziz University, Saudi Arabia.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability

Authors can confirm that all relevant data are included in the article and/or its supplementary information files.

Author contributions

All the authors made substantial contribution while preparing the manuscript.

Informed consent

A statement regarding informed consent is not applicable.