T Received: 17 September 2021 Accepted: 11 October 2021 Published: 14 OctoberAbstract: The improvement of reliable and very sensitive techniques for heavy metal detection is actually a important process for guarding the environment and human health. In this study, a qualitative colorimetric sensor that utilised mercaptosuccinic-acid-functionalized gold nanoparticles (MSA-AuNPs) to detect trace amounts of Fe(III) ions was created. MSA-AuNPs had been prepared utilizing a one-step reaction, where mercaptosuccinic acid (MSA) was utilized for both stabilization, which was offered by the presence of two carboxyl groups, and functionalization of your gold nanoparticle (AuNP) surface. The chelating properties of MSA in the presence of Fe(III) ions along with the concentration-dependent aggregation of AuNPs showed the effectiveness of MSA-AuNPs as a sensing probe together with the use of an absorbance ratio of A530 /A650 as an analytical signal inside the developed qualitative assay. Furthermore, the obvious Fe(III)-dependent change within the colour with the MSA-AuNP remedy from red to CDK| gray-blue made it possible to visually assess the metal content material in a concentration above the detection limit with an assay time of less than 1 min. The detection limit that was achieved (23 ng/mL) making use of the proposed colorimetric sensor is more than 10 instances decrease than the maximum allowable concentration for drinking water defined by the Globe Well being Organization (WHO). The MSA-AuNPs have been successfully applied for Fe(III) determination in tap, spring, and drinking water, having a recovery range from 89.six to 126 . Thus, the practicality on the MSA-AuNP-based sensor and its potential for detecting Fe(III) in genuine water samples were confirmed by the rapidity of testing and its higher sensitivity and selectivity in the presence of competing metal ions. Search phrases: mercaptosuccinic acid; gold nanoparticles; Fe(III) ions; colorimetry; aggregation; drinking water1. Introduction These days, manage on the good quality and composition of consumed drinking water is in particularly demand. The almost ubiquitous boost within the concentration of heavy metals, in certain iron ions, in water is often a significant concern for centralized water supply. The considerable amounts of Fe(III) can include wastewater from metallurgical, metalworking, textile, paint, and varnish industries, also as agricultural wastewater [1]. The primary kind of iron that may be present in surface waters is often a complex compound of Fe(III) with dissolved organic and inorganic compounds [2]; these ions are the object of study. In surface water, the procedure of transformation of Fe(III) to Fe(II) might take location [3], but the inorganic Fe(II) oxidizes back to Fe(III) in a couple of minutes [4]. This approach depends on the redox potential of all-natural water. Because a high consumption of Fe(III) can cause toxic effects [5], the determination of Fe(III) content material in drinking water resources is of good value for human life. Different efficient analytical approaches, including atomic absorption spectrometry [6], inductively coupled plasma mass spectrometry [7], liquid chromatography [8], and inductively coupled plasma optical emission spectrometry [9] are successfully applied forPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Copyright: 2021 by the authors. Licensee MDPI, Basel, Switzerland. This short article is definitely an open access post distributed below the terms and conditions of the Inventive Commons Attribution (CC BY) license (https://.