Preconcentration Of Arsenic Research Articles

Speciation of As(III) and As(V) in Food by Magnetic Dispersive Microsolid Phase Extraction with Dispersive Liquid–Liquid Microextraction with Graphite Furnace Atomic Absorption Spectrometry (GFAAS) Detection

Magnetic dispersive microsolid phase extraction (MDMSPE) was coupled with dispersive liquid–liquid microextraction (DLLME) for the separation and preconcentration of arsenic(V) and arsenic(III) prior to graphite furnace atomic absorption spectrometry detection. In the first step, magnetic ZnFe2O4 nanotubes were employed for adsorbing arsenic(V). The adsorbent was separated from the aqueous phase by the use of an external magnetic field. Next, arsenic(III) in the upper aqueous phase from MDMSPE was enriched by DLLME. Samples were prepared with artificial gastric juice to avoid inter-conversion of the determined species. The parameters affecting the separation and preconcentration of the determined species were optimized. The detection limits of this protocol were determined to be 1.3 and 2.0 pg mL − 1 for arsenic(III) and arsenic(V) with relative standard deviations of 4.5% and 5.6% for a concentration of 1.0 ng mL − 1 (n = 9). The enrichment factors were equal to 175-fold for arsenic(III) and 163-fold for arsenic(V). The developed protocol was employed for the determination of arsenic(III) and arsenic(V) in dairy products without preoxidation or prereduction. The recoveries of spiked samples were from 90.8% to 105%. A milk powder certified reference material was analyzed by this approach and the measured results were in good agreement with the certified value.

A Magnetized Nanoparticle Based Solid-Phase Extraction Procedure Followed by Inductively Coupled Plasma Atomic Emission Spectrometry to Determine Arsenic, Lead and Cadmium in Water, Milk, Indian Rice and Red Tea.

A sensitive and simple method using magnetic multi-walled carbon nanotube (MWCNTs-Fe3O4 MNP), as the adsorbent, has been successfully developed for extraction and pre-concentration of arsenic, lead and cadmium with detection by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The nanosorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction pattern (XRD), vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM). The key factors affecting the signal intensity such as pH, adsorbent amount, etc. were investigated. Under optimal conditions, the limits of detection (three-time of signal to noise ratio, S/N 3) were 0.3, 0.6, 0.3ng/mL for arsenic, lead and cadmium, respectively. Application of the adsorbent was investigated by the analysis of water, milk, Indian rice and red tea. The experimental data was analyzed and obeyed Langmuir and Freundlich adsorption models. The kinetic data was fitted to the pseudo-second-order model. Thermodynamic studies revealed the feasibility and exothermic nature of the system.

Magnetic Fe3O4@poly(methacrylic acid) particles for selective preconcentration of trace arsenic species

The authors describe magnetic nanoparticles consisting of an Fe3O4 core and a poly(methacrylic acid) coating for dispersive solid phase extraction (DSPE) of arsenic prior to its determination by hydride-generation microwave plasma AES (HG-MP-AES). The particles have an average size of 25 nm, can be prepared at low costs, and provide improved operational safety in combination with plasma generation. The methods allows arsenic to be determined with detection limits (at 3σ/m) of 3.0 ng⋅L−1 for As(III) and of 10.0 ng⋅L−1 of As(V). Recoveries of (spiked) samples range from 99.0 to 102%. This is the first report on the use of HG-MP-AES for speciation and preconcentration of arsenic using DSPE. The method displays detection limits that come close to those of ICP-OES and ICP-MS.

An evaluation of the bioaccessibility of arsenic in corn and rice samples based on cloud point extraction and hydride generation coupled to atomic fluorescence spectrometry

A simple, inexpensive and rapid method was proposed for the determination of bioaccessible arsenic in corn and rice samples using an in vitro bioaccessibility assay. The method was based on the preconcentration of arsenic by cloud point extraction (CPE) using o,o-diethyldithiophosphate (DDTP) complex, which was generated from an in vitro extract using polyethylene glycol tert-octylphenyl ether (Triton X-114) as a surfactant prior to its detection by atomic fluorescence spectrometry with a hydride generation system (HG-AFS). The CPE method was optimized by a multivariate approach (two-level full factorial and Doehlert designs). A photo-oxidation step of the organic species prior to HG-AFS detection was included for the accurate quantification of the total As. The limit of detection was 1.34μgkg−1 and 1.90μgkg−1 for rice and corn samples, respectively. The accuracy of the method was confirmed by analyzing certified reference material ERM BC-211 (rice powder). The corn and rice samples that were analyzed showed a high bioaccessible arsenic content (72–88% and 54–96%, respectively), indicating a potential human health risk.

Speciation of Inorganic Arsenic in Groundwater as Molybdoarsenate by On-Site Solid-Phase Extraction and Graphite Furnace Atomic Absorption Spectrometry

ABSTRACTSolid-phase extraction was used for on-site speciation and preconcentration of inorganic arsenic in groundwater involving the retention of molybdoarsenate on activated carbon. A total of 0.25 µg of As(V) in 50–500 mL of sample was selectively retained on 100 mg of activated carbon in a mini-column as molybdoarsenate at pH 2. A total of 0.1 mL of 0.26 mol/L ammonium molybdate was introduced for every 50 mL of the sample. As(III) was quantitatively retained with As(V) by adding 0.01 mL of 0.02 mol/L KMnO4 solution for every 50 mL of the sample prior to the addition of ammonium molybdate. The retained As(V) was quantitatively eluted by circularly passing 3 mL of 1 mol/L NH4OH through the column for at least 5 min with determination by graphite furnace atomic absorption spectrometry. A palladium chemical modifier was used to provide a detection limit and blank equivalent concentration of 0.047 and 0.19 µg/L, respectively (n = 6, sample volume of 50 mL). Concomitant ions in seawater or river water did not cause interferences. The method was used for the preconcentration of arsenic in groundwater from Chiba, Japan. The recoveries of fortified As(V) (2 µg/L) were from 89 to 98%. Concentrations of 0.35–1.6 µg/L of As(V) were determined with a relative standard deviation less than 3.7% for five replicates. The recoveries of 2 µg/L fortified As(III) were from 92 to 103%.

Preconcentration of Arsenic in <i>Radix aucklandiae</i> by Sulfhydryl Cotton and Determination by Atomic Fluorescence Spectrometry

Using sulfhydryl cotton for preconcentration of arsenic in Radix aucklandiae and determination of the arsenic by hydride generation-atomic fluorescence spectrometry. The samples were pretreated by high pressure digest. The experimental conditions such as negative high-voltage of instrument, preconcentration conditions and separation conditions of arsenic were studied and optimized. There was a good linear relationship between the fluorescence intensity and arsenic concentration in the range of 0-10μg/L with a correlation coefficient of 0.9997, while the detection limits was 0.06μg/L, and the relative standard deviation was 1.7% .The content of arsenic in the samples was 68.9-252.3µg/kg and the recovery was 90.0-95.0%.

Electrochemical Preconcentration of Arsenic(III) in Its Determination by Stripping Voltammetry at Graphite Electrodes Modified with Gold and Copper

The effect of some factors (potential and time of electrolysis, nature and concentration of supporting electrolyte) on the electrochemical preconcentration of arsenic at graphite electrodes modified with copper and gold adatoms was studied. The data obtained were used for the determination of 10–7to 10–6M arsenic(III) by stripping voltammetry. The detection limits for arsenic using graphite electrodes modified with copper and gold were 6.3 × 10–7and 2.3 × 10–7M, respectively.

Preconcentration of arsenic(V) as molybdoarsenic heteropoly acid by dynamic sorption

The sorption of molybdoarsenic heteropoly acid (MAA) and its ion pair with tri-n-octylamine (TOA) on sorbents of different nature and hydrophobic filters has been studied. It is demonstrated that MAA is efficiently extracted on the polyacrylate sorbent Amberlyte XAD-8; the distribution coefficient of arsenic is 1 x 104 cm3/g for the sorption from 0.35-1.5 M H2SO4. Conditions of the quantitative extraction of MAA in the presence of TOA on thin-layer cellulose triacetate filters are found. A procedure is proposed for the sorption-X-ray fluorescence determination of arsenic in potable water. The detection limit of arsenic is 10 Μg/L for the sorption from 100 mL of a solution.

Assessment of Constant Current Anodic Stripping Potentiometry for Determination of Arsenic in Fish and Water Samples

ABSTRACT An assessment of constant current anodic stripping potentiometry on a glassy carbon gold film electrode (GCAuFE) is described for the determination of arsenic in fish and water samples. The electrolytic preconcentration of arsenic, as As0, on the gold film was affected by the tendency for increased hydrogen evolution at longer deposition times (>3 min.), as well as by the presence of organic and inorganic substances. The hydrogen evolution problem was avoided by use of short deposition time (<1 min.), while organic and inorganic interferences were overcome either by sample decomposition and/or by use of standard additions for quantification. The decomposition of sample material by dry ashing with magnesium nitrate, as an ashing aid, enabled accurate determination of arsenic in fish on the GCAuFE. Reliable determination of arsenic in water samples was also accomplished after dilution with concentrated hydrochloric acid.