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Abstract
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This study presents an innovative
coacervation-based extraction method for detecting and quantifying trace levels of As(V) (including AsO43−, HAsO42−, and H2AsO4−) in aqueous
samples. The method utilizes the cationic surfactant
cetyltrimethylammonium bromide (CTAB) as both an
ion-pairing agent and extraction medium for As(V)
separation in the form of a dark blue, negatively
charged β-keggin molybdoarsenate complex. A watermiscible organic solvent is introduced to promote the
dispersion of the surfactant, enhance interactions with
the As(V) ions, and facilitate micelle formation. The
separation of the extracted phase is achieved through
centrifugation. Method efficacy was assessed via
UV–Vis spectrophotometry at 810 nm and a digital
image colorimetry technique. The results demonstrated remarkable sensitivity, with detection limits
as low as 0.17 µg L−1 for spectrophotometric analysis
and 3.4 µg L−1 for colorimetric analysis. Both limits
are significantly below the World Health Organization (WHO) recommended maximum of 10 µg L−1
for As(V) in drinking water. This method has been
successfully applied to real-world environmental
water samples, proving its practicality, reliability, and
potential as a robust analytical tool for monitoring
As(V) contamination.
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