Hydride generation coupled to microfunnel-assisted headspace liquid-phase microextraction for the determination of arsenic with UV-Vis spectrophotometry

Quantification of arsenic in real samples using a spectrophotometric cloud point extraction of the formed ion pair with astrazon orange G

A novel cloud-point extraction (CPE) procedure for the determination of ultra-trace amounts of arsenic species in real samples, purchased from the local market by spectrophotometer was developed. Inorganic arsenic species analysis in water, beverages, and foods has become increasingly important in recent years, as arsenic species are considered carcinogenic and are assessed at significant levels in samples. The technique is established on a selective ternary complex of As(V) with astrazon orange G (AOG+) in the presence of tartaric acid and polyethylene glycol tertoctylphenyl ether (Triton X-114) at pH 4.0. The calibration curve developed within range 3.0-160 ng/mL with a correlation coefficient of 0.9988 for As(V) provided a preconcentration factor of 200 and a limit of detection (3S blank/m) of 0.88 ng/mL under optimum investigation conditions. The results of molar absorptivity and Sandell sensitivity are calculated and found to be 4.38 × 105 L/mol cm and 0.018 ng cm-2, respectively. The statistical treatment of data obtained from the proposed and GF-AAS procedures are compared in terms of Student's t-tests and variance ratio F-tests has revealed no significant differences. The methodology has been effectively confirmed by assessing real samples and comparing it to the GF-AAS method statistically.

Integrated Solution for As(III) Contamination in Water Based on Crystalline Porous Organic Salts

A stable crystalline organic porous salt (CPOSs-NXU-1) with 1D apertures has been assembled by the solvothermal method, which shows high-sensitivity "turn-on" fluorescence detection and large-capacity adsorption of As(III) ions in water. The detection limits, saturated adsorption capacity, and removal rate of CPOSs-NXU-1 for As(III) ions in an aqueous solution can reach 74.34 nm (5.57 ppb), 451.01 mg g-1, and 99.6%, respectively, at pH = 7 and room temperature. With the aid of XPS, IR, Raman, and DFT theoretical calculations, it is determined that CPOSs-NXU-1 adsorbed As(III) ions in the form of H2AsO3 - and H3AsO3 through hydrogen bonding between the host and guest. The mechanism for fluorescence sensitization of As(III) ions to CPOSs-NXU-1 is mainly to increase the energy level difference between the ground state and excited state investigated by UV-vis absorption spectra, UV-vis diffuse reflectance spectra, and theoretical calculations. By constructing fluorescent CPOSs, an integrated solution has been achieved to treating As(III) contamination in the water that is equipped with detection and removal. These results blaze a promising path for addressing trivalent arsenic contamination in water efficiently, rapidly, and economically.

Determination of Arsenic Content in Water Using a Silver Coordination Polymer

In this report, we describe a practical method for the colorimetric determination of dissolved inorganic arsenic content in water samples, using a silver coordination polymer as the sensing material. We demonstrate that a crystalline polymer framework can be used to stabilize silver(I) ions, greatly reducing both photosensitivity and water solubility, while still affording sufficient reactivity to detect arsenic in water samples at low parts-per-billion (ppb) levels. Test strips fabricated with the silver-based polymer are shown to be effective for field tests of groundwater under real-world operating conditions and display performance that is competitive with commercially available mercury-based test strips. Spectroscopic methods are also used to probe the reaction products formed, in order to better understand the sensing mechanism. Thus, our work provides the foundation for an improved field test that could be deployed to help manage groundwater usage in regions where arsenic contamination is problematic but sophisticated lab testing is not readily available.

A colorimetric assay for the determination of trace arsenic based on in-situ formation of AuNPs with synergistic effect of arsine and iodide

In this work, we propose a colorimetric assay for the determination of trace arsenic based on in-situ formation of AuNPs with the synergistic effect of arsine (AsH₃) and iodide. AsH₃, generated by hydride generation of As^III in the sample or standard solution, enters into the HAuCl₄ solution containing polyvinyl alcohol (PVA) and KI, and then reacts rapidly to form AuNPs, resulting in the solution color changing from light yellow to pink. Hydride generation applied here not only produces a strong reducing agent AsH₃, but also effectively reduces matrix interference. The introduction of I^- promotes the reaction by reducing the Au precursor from trivalent state to monovalent state, thus accelerating the formation of AuNPs with AsH₃ and improving the sensitivity for the detection of arsenic. Trace As^III as low as 10 μg L^-1 in 3 mL sample solution can produce the change in color visible to the naked eye. Moreover, the use of the stabilizer PVA and the gaseous strong-reducing agent AsH₃ evenly dispersed in the reaction solution lead to the formation of well-distributed and fine AuNPs of size changing little with the dosage of AsH₃. The whole analysis process only takes 30 min under ambient condition without complicated synthesis and pretreatment. The proposed assay is simple, stable, sensitive and selective, providing a convenient and cost-effective choice for on-site trace arsenic detection in real samples.

Spectrophotometric determination of low levels arsenic species in beverages after ion-pairing vortex-assisted cloud-point extraction with acridine red

A new, low-cost, micellar-sensitive and selective spectrophotometric method was developed for the determination of inorganic arsenic (As) species in beverage samples. Vortex-assisted cloud-point extraction (VA-CPE) was used for the efficient pre-concentration of As(V) in the selected samples. The method is based on selective and sensitive ion-pairing of As(V) with acridine red (ARH(+)) in the presence of pyrogallol and sequential extraction into the micellar phase of Triton X-45 at pH 6.0. Under the optimised conditions, the calibration curve was highly linear in the range of 0.8-280 µg l(-1) for As(V). The limits of detection and quantification of the method were 0.25 and 0.83 µg l(-1), respectively. The method was successfully applied to the determination of trace As in the pre-treated and digested samples under microwave and ultrasonic power. As(V) and total As levels in the samples were spectrophotometrically determined after pre-concentration with VA-CPE at 494 nm before and after oxidation with acidic KMnO4. The As(III) levels were calculated from the difference between As(V) and total As levels. The accuracy of the method was demonstrated by analysis of two certified reference materials (CRMs) where the measured values for As were statistically within the 95% confidence limit for the certified values.