Colorimetric Detection of Arsenic (III) and Mercury (II) Ions in

Overview

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Key numbers

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• LOD, as low as 0.02 ppm for Hg (II), demonstrates the method’s sensitivity.
figures of merit (R2 ≥ 0.940) and the low detection limits (0.05 ppm for As (III) ions and
0.02 ppm for Hg (II)) in serum albumin demonstrate the high sensitivity of the method.
conditions of the Creative Commons ≥95% over a period of seven months without recalibrations, demonstrating the stability of
selectivity for arsenic and mercury (28–31). The study also focused on using portable
element ions (37). Blood levels of Hg below 50 µg/dL (or 0.5 ppm) are considered normal;
Lyophilized human serum albumin (HSA) (agarose gel electrophoresis, purity > 97%),
3-(N-morpholino) propanesulfonic acid (MOPS, purity > 99.5%), L-cysteine, and gold
used as received. As (III) and Hg (II) element reference standards (1000 ppm %) were
and working range serum albumin solutions were prepared in MOPS buffer (30 mM,
assays (42). The working range for As (III) or Hg (II) ion concentrations was prepared
from 1000 ppm of As (III) or Hg (II) reference standard solutions. The absorption spectra
device accessory, scanning the 200–600 nm wavelength range (bandwidth, 2.5 nm; quartz
standard deviation from triplicate measurements (N = 3).
of −33 mV, indicating that they are stable in water (Figure 2). Interestingly, the negative
triplicate measurements (N = 3).
HSA samples at varying known concentrations (0 ppm to 50 ppm) of either As(III) or
as evidenced by LODs of 16 ppm and 29 ppm for As (III) and Hg (II), respectively. The
element-specific (44). The LOD by XRF for arsenic detection in this study is comparable
to the levels reported by Capobianco et al. for Pteris vittata (45). The use of a portable
HSA 0µL Cys AuNP HSA 2ppm As 0µL Cys AuNP
HSA + 4ppm As (III) HSA 6ppm As 0µL Cys AuNP
HSA 8ppm As 0µL Cys AuNP HSA 10ppm As 0µL Cys AuNP
HSA 12ppm As 0uL Cys AuNP
HSA 2ppm Hg 0µL Cys AuNP HSA 4ppm Hg 0µL Cys AuNP
HSA 6ppm Hg 0µL Cys AuNP HSA 8ppm Hg 0µL Cys AuNP
HSA 10ppm Hg 0µL Cys AuNP HSA 12ppm Hg 0µL Cys AuNP
Figure 3. (A) UV–visible spectra of a solution of varying concentrations (2 ppm to 12 ppm) of As (III)
HSA was observed at higher Hg (II) concentrations (≥10 ppm), which could affect serum
(II) ion concentrations (2 ppm to 12 ppm) in serum albumin with the addition of 25 µL of
HSA 0µL Cys AuNP HSA 2ppm As 25µL Cys AuNP
HSA 4ppm As 25µL Cys AuNP HSA 8ppm As 25µL Cys AuNP
HSA 10ppm As 25µL Cys AuNP HSA 12ppm As 25µL Cys AuNP
HSA 2ppm Hg 25µL Cys AuNP
HSA 6ppm Hg 25µL Cys AuNP C
HSA 4ppm Hg 25µL Cys AuNP
HSA 8ppm Hg 25µL Cys AuNP
solutions of varying As (III) ion concentrations (2 ppm to 12 ppm) in serum albumin with the addition
of 25 µL of CysAuNPs (LOD = 0.02 ppm). (C) UV–visible absorption of solutions of varying Hg (II)
ion concentrations (2 ppm to 12 ppm) in serum albumin with the addition of 25 µL of CysAuNPs
analysis, and m is the slope of the regression line (64) of 0.05 ppm for As (III) and 0.02 ppm
from these results is comparable to or lower than the reported LOD value of 0.026 ppm

Methods (brief)

Human Serum Albumin Samples Using Cysteine-Capped
• LOD, as low as 0.02 ppm for Hg (II), demonstrates the method’s sensitivity.
relevant biological samples.
(II) and As (III) in biological samples stems from the toxic effects of human exposure to
distributed under the terms and (II) ions of independently prepared test validation samples in HSA with an accuracy of
and determination of heavy metal ions in biological samples arises from the toxic and
quantification of arsenic and mercury ions in serum samples, and CD spectroscopy for
changes. Serum albumin and blood samples are vital in biomedical and toxicological
2.1. Chemicals, Consumables, and Sample Preparation
pH 7.4), as previously described elsewhere (41). MOPS was selected for sample preparation
were collected using a UV–visible spectrophotometer (Shimadzu 2600i) with a temperature-
2.2. Preparation of Nanoparticle Samples, Characterization, and Instrumental Analysis
cuvette, 1 cm path length). The sample was equilibrated for one hour to allow for the
at physiological conditions of 37 ◦ C and pH 7.4. The X-ray fluorescence (XRF) sample
measurement was performed by filling XRF sample cups (30.7 mm OD × 22.9 mm high,
1330-SE, Chemplex Industries Inc., Palm City, FL, USA) with an HSA sample containing
known concentrations of As (III) or Hg (II) ions. The sample was covered with a Prolene
a Geochem (3-Beam) setting (50 kV three beam). Sample circular dichroism (CD) spectra

Implications

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised