Colorimetric determination of trace orthophosphate in water by using C18-functionalized silica coated magnetite

Abstract

In this study, we customized magnetic sorbents by functionalizing silica coated magnetite with octadecyl(C18)silane (Fe3O4@SiO2@C18). This sorbent was intended for the determination of trace orthophosphate (o-PO43−) in unpolluted freshwater samples. The o-PO43− was transformed to phosphomolybdenum blue (PMB), a known polyoxometalate ion. Then the PMB were coupled with cetyl trimethyl ammonium bromide (CTAB), cationic surfactant, in order to hydrophobically bound with the Fe3O4@SiO2@C18 particles through dispersive magnetic solid-phase extraction (d-MSPE) as part of sample preconcentration. The PMB–CTAB–magnetic particles are simply separated from the aqueous solution by the external magnet. The acidified ethanol 0.5 mL was used as PMB-CTAB eluent to produce an intense blue solution, which the absorbance was measured using a UV–Vis spectrophotometer at 800 nm. The proposed method (employing 2 mg of Fe3O4@SiO2@C18) yielded an enhancement factor of 32 with a linear range of 1.0–30.0 µg P L−1. Precision at 6.0 µg P L−1 and 25.0 µg P L−1 were 3.70 and 2.49% (RSD, n = 6) respectively. The lower detection limit of 0.3 µg P L−1 and quantification limit of 1.0 µg P L−1 allowed trace levels analysis of o-PO43− in samples. The reliability and accuracy of the proposed method were confirmed by using a certified reference material. Our method offers highly sensitive detection of o-PO43− with simple procedures that can be operated at room temperature and short analysis time.

Tuning the Fluorometric Sensing of Phosphate on UiO-66-NH2(Zr, Ce, Hf) Metal Nodes

“…Identification of zones with high P concentrations that are at risk of eutrophication requires effective tools for monitoring P levels . The conventional analytical test for P detection relies on a tedious and laborious method employing molybdenum blue that involves using a number of reagents and incubation steps, and requires sequential mixing and time monitoring. , Materials such as MOFs, nanoparticles, metal complexes can be used as potential probes for P but in order to be used for sensing, in addition to P-recognition, they require a transduction modality so that binding can be measured by methods such as fluorometric, , colorimetric, , and electrochemical techniques. − Despite the discovery of many materials with P-binding ability, their use as probes and detection tools that can measure P in eutrophic zones is still limited. In addition, a fundamental understanding of the molecular origin of P recognition and detection capability is still needed to rationally design effective monitoring tools.…”

A colorimetric assay with leuco crystal violet for the detection of inorganic phosphate in water

“…1.67 × 10 -3 -8.34 × 10 -2 4.17 × 10 -4 [8] Digital imaging with Image J software RGB analyses (via ImageJ) 0.1 -10 ppm 0.28 ppm [9] UV-Vis spectroscopy Molybdenum blue colorimetric method Up to 10 μM 0.07 μM [10] UV-Vis spectroscopy Using C18-functionalized silica coated magnetite 1.0 -30.0 µg P L −1 0.3 µg P L −1 [11] UV-Vis spectroscopy Novel colorimetric probe (TNT@MB)…”

Magnetic Adsorbents for Wastewater Treatment: Advancements in Their Synthesis Methods

“…In addition to environmental remediation applications, magnetic adsorbents have been used in analytical chemistry in the so-called magnetic solid-phase extraction sample preparation technique. This technique is used to clean up and pre-concentrate the samples, before core analysis improves the detection of anions [ 12 ] and organic pollutants [ 13 ].…”