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A slurry sampling procedure for arsenic speciation analysis in baby food by arsane generation, cryogenic trapping and detection with atomic absorption spectrometry is presented. Several procedures were tested for slurry preparation, including different reagents (HNO 3 , HCl and tetramethylammonium hydroxide – TMAH) and their concentrations, water bath heating and ultrasound-assisted agitation. The best results for inorganic arsenic (iAs) and dimethylarsinate (DMA) were reached when using 3 mol L −1 HCl under heating and ultrasound-assisted agitation. The developed method was applied for the analysis of five porridge powder and six baby meal samples. The trueness of the method was checked with a certified reference material (CRM) of total arsenic (tAs), iAs and DMA in rice (ERM-BC211). Arsenic recoveries (mass balance) for all samples and CRM were performed by the determination of the tAs by inductively coupled plasma mass spectrometry (ICP-MS) after microwave-assisted digestion and its comparison against the sum of the results from the speciation analysis. The relative limits of detection were 0.44, 0.24 and 0.16 µg kg −1 for iAs, methylarsonate and DMA, respectively. The concentrations of the most toxic arsenic species (iAs) in the analyzed baby food samples ranged between 4.2 and 99 µg kg −1 which were below the limits of 300, 200 and 100 µg kg −1 set by the Brazilian, Chinese and European legislation, respectively. [ABSTRACT FROM AUTHOR]

Accurate, stable and fast analysis of toxic inorganic arsenic (iAs) in complicated and arsenosugar-rich algae matrix is always a challenge. Herein, a novel analytical method for iAs in algae was reported, using bromine halogenation and on-line nonpolar solid phase extraction (SPE) followed by hydride generation atomic fluorescence spectrometry (HG-AFS). The separation of iAs from algae was first performed by nonpolar SPE sorbent using Br - for arsenic halogenation. Algae samples were extracted with 1% perchloric acid. Then, 1.5 mL extract was reduced by 1% thiourea, and simultaneously reacted (for 30 min) with 50 μL of 10% KBr for converting iAs to AsBr 3 after adding 3.5 mL of 70% HCl to 5 mL. A polystyrene (PS) resin cartridge was employed to retain arsenicals, which were hydrolyzed, eluted from the PS resin with H 2 O, and categorized as iAs. The total iAs was quantified by HG-AFS. Under optimum conditions, the spiked recoveries of iAs in real algae samples were in the 82–96% range, and the method achieved a desirable limit of detection of 3 μg kg −1 . The inter-day relative standard deviations were 4.5% and 4.1% for spiked 100 and 500 μg kg −1 respectively, which proved acceptable for this method. For real algae samples analysis, the highest presence of iAs was found in sargassum fusiforme , followed by kelp, seaweed and laver. [ABSTRACT FROM AUTHOR]

Direct solid sample analysis with graphite furnace atomic absorption spectrometry (SS-GF AAS) was investigated initially with the intention of developing a method for the determination of total As in fish and other seafood. A mixture of 0.1% Pd+0.06% Mg+0.06% Triton X-100 was used as the chemical modifier, added in solution over the solid samples, making possible the use of pyrolysis and atomization temperatures of 1200 °C and 2400 °C, respectively. The sample mass had to be limited to 0.25 mg, as the integrated absorbance did not increase further with increasing sample mass. Nevertheless, the recovery of As from several certified reference materials was of the order of 50% lower than the certified value. Strong molecular absorption due to the phosphorus monoxide molecule (PO) was observed with high-resolution continuum source AAS (HR CS AAS), which, however, did not cause any spectral interference. A microwave-assisted digestion with HNO 3 /H 2 O 2 was also investigated to solve the problem; however, the results obtained for several certified reference materials were statistically not different from those found with direct SS-GF AAS. Accurate values were obtained using inductively coupled plasma mass spectrometry (ICP-MS) to analyze the digested samples, which suggested that organic As compounds are responsible for the low recoveries. HPLC–ICP-MS was used to determine the arsenobetaine (AB) concentration. Accurate results that were not different from the certified values were obtained when the AB concentration was added to the As concentration found by SS-GF AAS for most certified reference materials (CRM) and samples, suggesting that SS-GF AAS could be used as a fast screening procedure for inorganic As determination in fish and seafood. [ABSTRACT FROM AUTHOR]

The extraction of arsenic (As) species present in rice flour samples was investigated using different extracting solvents, and the concentration of each species was determined by HPLC-ICP-MS after heat-assisted extraction. The extraction efficiencies for total arsenic species and especially for arsenite [As(III)] and arsenate [As(V)] were investigated. As(III), As(V) and dimethylarsinic acid (DMAA) were found in the samples, and the concentration of DMAA did not vary with treatment conditions. However, the concentrations of extracted total arsenic and those of As(III) and As(V) depended on the extracting solvents. When an extracting solvent was highly acidic, the concentrations of extracted total arsenic were in good agreement with the total arsenic concentration determined by ICP-MS after microwave-assisted digestion, though a part of the As(V) was reduced to As(III) during the highly acidic extraction process. Extraction under neutral conditions increased the extracted As(V), but extracted total arsenic was decreased because a part of the As(III) could not be extracted. Optimum conditions for the extraction of As(III) and As(V) from rice flour samples are discussed to allow the accurate determinations of As(III), As(V) and DMAA in the rice flour samples. Heat block extraction techniques using 0.05 mol L-1 HClO4 and silver-containing 0.15 mol L-1 HNO3 were also developed. [ABSTRACT FROM AUTHOR]

Abstract: Dispersive-solidification liquid–liquid microextraction (DSLLME) coupled with electrothermal atomic absorption spectrometry (ETAAS) was developed for preconcentration and determination of inorganic arsenic (III, V) in water samples. At pH=1, As(III) formed complex with ammonium pyrrolidine dithiocarbamate (APDC) and extracted into the fine droplets of 1-dodecanol (extraction solvent) which were dispersed with ethanol (disperser solvent) into the water sample solution. After extraction, the organic phase was separated by centrifugation, and was solidified by transferring into an ice bath. The solidified solvent was transferred to a conical vial and melted quickly at room temperature. As(III) was determined in the melted organic phase while As(V) remained in the aqueous layer. Total inorganic As was determined after the reduction of the pentavalent forms of arsenic with sodium thiosulphate and potassium iodide. As(V) was calculated by difference between the concentration of total inorganic As and As(III). The variable of interest in the DSLLME method, such as the volume of extraction solvent and disperser solvent, pH, concentration of APDC (chelating agent), extraction time and salt effect, was optimized with the aid of chemometric approaches. First, in screening experiments, fractional factorial design (FFD) was used for selecting the variables which significantly affected the extraction procedure. Afterwards, the significant variables were optimized using response surface methodology (RSM) based on central composite design (CCD). In the optimum conditions, the proposed method has been successfully applied to the determination of inorganic arsenic in different environmental water samples and certified reference material (NIST RSM 1643e). [Copyright &y& Elsevier]

Due to high toxicity, inorganic arsenic (iAs) species are the focus of monitoring effort worldwide. In this work arsenic was first extracted from rice by microwave-assisted digestion in HNO3–H2O2, during which AsIII was oxidized to AsV. Silica-based strong anion exchange cartridges were used to separate AsV from organic forms. After prereduction by iodide, iAs was quantified by hydride-generation atomic fluorescence spectrometry (HG-AFS). This method achieved 1.3ngg−1 limit of detection (LOD), and 94±3% and 93±5% recoveries, respectively, for AsIII and AsV at 100ngg−1. Validation was performed using standard reference material NIST 1568a (102ngg−1) and ERM BC211 (124ngg−1) rice flour. By eliminating chromatography, SPE speciation gained throughput and cost advantages. HG-AFS, at 10% budget and operation cost of a typical inductively-couple plasma mass spectrometer (ICPMS), proved highly sensitive and specific for iAs quantification. [ABSTRACT FROM AUTHOR]

Abstract: A proof of concept of a novel pervaporation sequential injection (PSI) analysis method for automatic non-chromatographic speciation analysis of inorganic arsenic in complex aqueous samples is presented. The method is based on hydride generation of arsine followed by its on-line pervaporation-based membrane separation and CCD spectrophotometric detection. The concentrations of arsenite (As(III)) and arsenate (As(V)) are determined sequentially in a single sample zone. The leading section of the sample zone merges with a citric acid/citrate buffer solution (pH 4.5) for the selective reduction of As(III) to arsine while the trailing section of the sample zone merges with hydrochloric acid solution to allow the reduction of both As(III) and As(V) to arsine at pH lower than 1. Virtually identical analytical sensitivity is obtained for both As(III) and As(V) at this high acidity. The flow analyzer also accommodates in-line pH detector for monitoring of the acidity throughout the sample zone prior to hydride generation. Under optimal conditions the proposed PSI method is characterized by a limit of detection, linear calibration range and repeatability for As(III) of 22μgL−1 (3sblank level criterion), 50–1000μgL−1 and 3.0% at the 500μgL−1 level and for As(V) of 51μgL−1, 100–2000μgL−1 and 2.6% at the 500μgL−1 level, respectively. The method was validated with mixed As(III)/As(V) standard aqueous solutions and successfully applied to the determination of As(III) and As(V) in river water samples with elevated content of dissolved organic carbon and suspended particulate matter with no prior sample pretreatment. Excellent relative recoveries ranging from 98% to 104% were obtained for both As(III) and As(V). [Copyright &y& Elsevier]

Abstract: A new method was developed for the speciation analysis of inorganic arsenic in coal samples by high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry after microwave-assisted extraction. Effective extract of As(III) and As(V) in coal sample was achieved by 1.0molL−1H3PO4 and 0.1molL−1ascorbic acid. Under the optimized conditions, the limits of detection (LOD) were 0.01μgL−1 and 0.02μgL−1, the relative standard deviations (RSD) were 2.4% and 3.3% (c=10.0μgL−1, n=7), recoveries were 102.5% and 96.5% for As(III) and As(V). The proposed method was successfully applied for the determination of speciation of inorganic arsenic in coal samples and GBW11117 coal standard reference material with complex matrix. [Copyright &y& Elsevier]

Abstract: A miniaturized solid phase extraction procedure has been developed for ultra-trace determination of inorganic arsenic species. Arsenic(III) as pyrrolidinedithiocarbamate complex was selectively adsorbed on 30mg poly(hydroxyethyl methacrylate) (PHEMA) micro beads, which is simply packed into a micro-pipette-tip. The adsorbed arsenic was quantitatively eluted by 700μL 0.25M NH3 and determined by graphite furnace atomic absorption spectrometry (GFAAS). Injection of larger volume (i.e., 50μL v.s. conventional 10–20μL) eluent into graphite furnace and the use of Mg(NO3)2 as chemical modifier have improved atomic absorption signal intensity (sensitivity as characteristic mass of 25pg) and precision (RSD of 2.6%, c=10μgL−1, n=11). Total arsenic amount was determined after reduction of arsenic(V) to arsenic(III) by thiourea-HCl system. As(V) concentration was calculated by the difference between As(III) and total arsenic. The detection limit (3s) of the method was found as 10ngL−1 As(III) with an enrichment factor of 86. The relative standard deviation and relative error for six replicate determinations of 0.5μgL−1 As(III) were found to be 4.0% and −0.7%, respectively. The method was successfully applied to drinking water, snow and reference water (SEM-2011) samples. When the samples were spiked with 0.5 and 1.0μgL−1 As(III) and As(V), the recoveries varied between 96 and 100%. [Copyright &y& Elsevier]

Abstract: A gas chromatography method with atomic emission detection (GC-AED) for the determination of dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and inorganic arsenic was optimized. The analytes were derivatized in the sample solutions with methyl thioglycolate (TGM) and the products were extracted into cyclohexane before an aliquot of this organic phase was directly injected into the chromatograph. The procedure was applied to the analysis of seawaters, wines, beers and infant foods, the last requiring an additional enzymatic reaction prior to analyte derivatization. Detection limits in seawaters and beverages were 0.05, 0.15 and 0.8ngmL−1 for DMA, MMA and inorganic arsenic, respectively. In infant foods the detection limits were 1, 10 and 25ngg−1 for DMA, MMA and inorganic arsenic, respectively. Inorganic arsenic was detected in some of the seawater samples and three of the wines analyzed at concentration levels in the range 1–40ngmL−1, and DMA in several of the infant foods in the range 20–80ngg−1. The method was validated by analyzing a certified reference material and by recovery studies. All the samples were also analyzed by hydride generation and atomic fluorescence spectrometry (HG-AFS), which provided data for the total arsenic content. [Copyright &y& Elsevier]

Inorganic arsenic, a term which encompasses both As (III) and As (V) species, constitutes the highest toxicological risk associated with arsenic in water in contrast to the organic arsenic species. Different determination methods of inorganic arsenic have been developed over 40 years providing timely and efficient risk assessments of inorganic arsenic contamination world wide. The current report gives an overview of more than 100 papers, regarding existing methods for analysis of As (III) and As (V) in water, including various spectroscopic, ICP and electrochemical techniques. Recent field portable analytical applications are also reviewed. [Copyright &y& Elsevier]

This study combines ultrasound-assisted extraction and vortex-assisted dispersive micro-solid phase extraction using an ionic imprinted polymer as a selective sorbent for rapid isolation and pre-concentration of inorganic arsenic species (As(III) and As(V)) in extracts from rice samples prior to their determination by high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry. All factors affecting the ultrasound assisted extraction of the species from rice (ultrasound amplitude, sonication time and sonication mode) and their selective pre-concentration by ionic imprinted polymer-based vortex-assisted dispersive micro-solid phase extraction (sorbent amount, extract pH, vortex extraction time and speed, eluting solution and vortex elution time and speed) were optimized. The analytical performance of the procedure was studied at optimum conditions: ultrasound continuous sonication at 40% amplitude for 2.0 min using 1:1 methanol/ultrapure as an extractant, 50 mg of sorbent, extract pH at 8.0, vortex loading at 1000 rpm for 1.0 min, and elution with ultrapure water by vortexing at 1000 rpm for 1.0 min, pre-concentration procedure which leads to a pre-concentration factor of 10. The limits of detection obtained for As (III) and As (V) were 0.20 and 0.41 μg kg−1, respectively, and were well below the maximum levels established by the European Union in rice and rice containing products. The method was found to be precise (intraday and interday relative standard deviations ≤ 11%) and selective. The accuracy was confirmed by analysing the ERM-BC211 (rice, As species) certified reference material, and the method was successfully applied to commercial rice samples. Image 1 • A vortex-assisted dispersive micro-SPE was used to separate and pre-concentrate iAs. • The ion-imprinted polymeric sorbent was selective for iAs. • iAs (As(III) plus As(V)) can be assessed by ICP-MS. • As(III) and As(V) species can be assessed by HPLC-ICP-MS. • The LOQ of the method is lower than the iAs levels in rice set by safety authorities. [ABSTRACT FROM AUTHOR]

The extraction of arsenic (As) species present in rice flour samples was investigated using different extracting solvents, and the concentration of each species was determined by HPLC-ICP-MS after heat-assisted extraction. The extraction efficiencies for total arsenic species and especially for arsenite [As(III)] and arsenate [As(V)] were investigated. As(III), As(V) and dimethylarsinic acid (DMAA) were found in the samples, and the concentration of DMAA did not vary with treatment conditions. However, the concentrations of extracted total arsenic and those of As(III) and As(V) depended on the extracting solvents. When an extracting solvent was highly acidic, the concentrations of extracted total arsenic were in good agreement with the total arsenic concentration determined by ICP-MS after microwave-assisted digestion, though a part of the As(V) was reduced to As(III) during the highly acidic extraction process. Extraction under neutral conditions increased the extracted As(V), but extracted total arsenic was decreased because a part of the As(III) could not be extracted. Optimum conditions for the extraction of As(III) and As(V) from rice flour samples are discussed to allow the accurate determinations of As(III), As(V) and DMAA in the rice flour samples. Heat block extraction techniques using 0.05 mol L(-1) HClO4 and silver-containing 0.15 mol L(-1) HNO3 were also developed., (Copyright © 2014 Elsevier B.V. All rights reserved.)