O-arsanilic Acid Research Articles

Speciation of organoarsenicals in aqueous solutions by Raman spectrometry and quantum chemical calculations

Knowledge about the existence and stability of different species of organoarsenicals in solution is of the most significant interest for fields so different as chemical, environmental, biological, toxicological and forensic. This work provides a comparative evaluation of the Raman spectra of four organoarsenicals (o-arsanilic acid, p-arsanilic acid, roxarsone and cacodylic acid) in aqueous solutions under acidic, neutral and alkaline conditions. Speciation of some of these organoarsenicals is possible by Raman spectrometry at different selected pHs. Further, we examine the proficiency of computational chemistry to obtain the theoretical Raman spectra of the four organoarsenicals compounds. To this end, we employ a computational protocol that includes explicit water molecules and conformational sampling, finding that the calculated organoarsenicals spectra agree reasonably well with those experimentally obtained in an aqueous solution in the whole pH range covered. Finally, we highlight the effectiveness of quantum chemical calculations to identify organoarsenicals in an aqueous solution.

Study on interaction of p-sulfonato calix[6]arene with arsanilic acid

The interaction of p-sulfonatocalix[6]arene (PSC6) with o-arsanilic acid (OASA) and p-arsanilic acid (PASA) was studied by UV–Visible spectroscopy, high-performance liquid chromatography (HPLC) analysis, photoluminescence (PL) spectra, and nuclear magnetic resonance (NMR) studies. The studies confirm the inclusion of PASA in PSC6 cavity.

Experimental study and DFT calculation for the strength of intermolecular interactions in Schiff base with the phenylarsonic acid scaffold

The crystal structure and supramolecular architectures of Schiff bases derived from the o-arsanilic acid, (E)-(2-(4-hydroxybenzylidene)aminophenyl)arsonic acid(I); (E)-(2-(4-methoxybenzylidene)aminophenyl)arsonic acid (II) and (E)-(2-(3-cyanobenzylidene)aminophenyl)arsonic acid (III) are reported. The intermolecular interactions, supramolecular architectures, and molecular conformations are compared with the (E)-(2-(2-hydroxybenzylidene)aminophenyl)arsonic acid(IV) to evaluate how different substituents influence the crystal packing. In the solid state, the O−H⋯O hydrogen bonding interaction predominantly stabilizes the crystal structures of I-IV. Further, the weak intermolecular C−H⋯O, C−H⋯N, C−H···π, π···π, and H⋯H contacts form a self-assembled motif. Various intermolecular interactions exist in I-IV and their energies are quantified using PIXEL, DFT and QTAIM analysis. The variant and invariant arsanilic acid dimers are observed in I-IV. The distribution of electrostatic potential on the molecular surface is found to be asymmetric nature in I-IV. The relative contributions of various intermolecular contacts in the I-III and the closely related analog (IV) are quantified by using Hirshfeld surface analysis and the decomposed 2D fingerprint plots. The total lattice energy of compound III is higher than the other compounds. It is due to the cyano substitution in III because the −CN group participates in the C−H⋯N interactions which favored very compact packing. Also, the contribution of intermolecular H⋯H, O⋯H/H⋯O, and C⋯H/H⋯C contacts are drastically reduced in III when compared with other compounds, this reduction is due to more contribution of H⋯N contacts in the crystal structure.

Determination of residual arsenic compounds in chicken muscle by ultra-performance liquid chromatography coupled with ultraviolet detection after pre-column derivatization with toluene-3,4-dithiol.

A simple and sensitive derivatization method using toluene-3,4-dithiol as a derivatization reagent for the simultaneous analysis of seven arsenic compounds (roxarsone, nitarsone, p-arsanilic acid, o-arsanilic acid, phenylarsonic acid, phenylarsine oxide, and mono-methylarsonic acid) in chicken muscle was developed and validated by ultra-performance liquid chromatography coupled with ultraviolet detection (UPLC-UV). The structure of the derivatized arsenic compounds was confirmed by liquid chromatography-ion trap mass spectrometry or gas chromatography-mass spectrometry. Optimization of the derivatization reaction conditions was carried out by investigating the influence of reagent concentration, buffer or additive acids, temperature, and time. The optimized conditions were a derivatization reagent concentration of 20mg/mL with 0.05mol/L HCl as an additive acid at 60°C for 15min. In this study, baseline separation of arsenic compounds could be achieved within 13min, except for phenylarsonic acid and phenylarsine oxide whose derivatized products are equal. The developed method was successfully validated and applied to 12 chicken muscle samples from Korean districts and other countries.

Speciation analysis of arsenic compounds by capillary electrophoresis on-line coupled with inductively coupled plasma mass spectrometry using a novel interface

In this work, a capillary electrophoresis (CE) coupled with inductively coupled plasma mass spectrometer (ICP-MS) system was developed for the simultaneous determination of ten arsenic compounds including arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, arsenocholine, 3-nitro-4-hydroxyphenylarsonic acid, o-Arsanilic acid, p-ureidophenylarsonic acid, and 4-nitrophenylarsonic acid. The CE-ICP-MS system was hyphenated by a novel and high efficient interface which was directly used as the nebulizer. The separation was achieved on a 100cm length×50μm ID fused-silica capillary. Analytical conditions such as electrophoretic buffer composition, concentration and pH value, separation voltage, methanol concentration in the sheath flow liquid and sample injection time were optimized. Baseline separation of the ten arsenic species was achieved using an electrophoretic buffer consisting of 12mM NaH2PO4 and 8mM HBO3 at pH 9.20 with an applied voltage of +30kV. The detection limits of the ten arsenic compounds ranged from 0.9 to 3.0ngAsg−1, corresponding to absolute detection limits in the range of 19–65fg As and the relative standard deviations (RSD, n=5) were below 1.5%, 5.7% and 4.8% for migration time, peak height and peak area, respectively. This method was successfully applied to determine various arsenicals in two certified reference materials (TORT-2 and DORM-3) and environmental samples such as ground water samples, herbal plants and chicken meat.

Identification of degradation products of phenylarsonic acid and o-arsanilic acid in contact with suspensions of soils of volcanic origin

A set of organoarsenicals were identified in aqueous phenylarsonic acid (PA) and o-arsanilic acid (AA) solutions treated with soil of volcanic origin in batch systems. The transformation products were separated by liquid chromatography (RP-LC) and identified with element selective inductively coupled plasma-mass spectrometry (ICP-MS) as well as molecular selective electrospray ionization-mass spectrometry (ESI-MS) detection after their HPLC separation. The identification of the main degradation products by means of ESI-MS, ESI-MS/MS and ESI-TOF-MS showed the occurrence of nitrophenylarsonic acid and methylphenylarsinic acid in the solutions containing AA and PA in contact with soils, respectively. Using irradiation of PA solution with visible light, new compounds related from PA appeared with increasing irradiation times which were identified as 4-hydroxyphenylarsonic acid, 3-hydroxyphenylarsonic acid and 2-hydroxyphenylarsonic acid. Additionally, a dihydroxyphenylarsonic compound was identified as impurity of PA.

Retention of phenylarsenicals in soils derived from volcanic materials

Sorption of phenylarsenicals including 4-hydroxy-3-nitrophenylarsonic acid (roxarsone), an animal feed additive widely used for growth stimulation, on soils was investigated in batch systems. Phenylarsonic acid, o-arsanilic acid and roxarsone were retained differently by unpolluted, non-sterilized soils. Sorption isotherms were analyzed by the Henry, Tóth and Langmuir–Freundlich equations. The saturation capacity of the Acrisol soil was 3.4 for o-arsanilic acid, 10.9 for phenylarsonic acid and 1.9gAskgsoil−1 (dry mass) for roxarsone. The iron content in the soil was not the only factor determining retention of the studied phenylarsenicals. The order of retention on the three soils after 24h was: roxarsone>o-arsanilic acid>phenylarsonic acid. Besides arsenite and arsenate, new arsenic-containing compounds were detected.

Crystal and molecular structure of o-methacryloylaminophenylarsonic acid

The title compound, o-methacryloylaminophenylarsonic acid (o-MAPHA), C10H12AsNO4, is a monomer used to obtain water-soluble polyelectrolytes. It was obtained from the condensation reaction of o-arsanilic acid and methacryloyl chloride. Crystallization from aqueous ethanol solution yielded colorless prismatic crystals, and one was used for X-ray analysis. The crystal structure was solved using direct methods with a refined R1 = 0.0483. The crystal structure belongs to the triclinic system, space group \(P\bar 1\), and the asymmetric unit comprises two molecules of the o-MAPHA acid and one water molecule. Both acid molecules are approximately planar and in both molecules the As atom presents common tetrahedral geometry with two long As–O bonds for hydroxyl groups and one short As–O bond for the oxo groups. The structure of o-arsanilic acid (o-ARSA), C6H8AsNO3, was also determinated using the same methods and compared with the o-arsanilic acid structure previously reported. The crystal structure of the o-arsanilic acid belongs to the monoclinic crystal system and to the P21 noncentrosymmetric space group with Z equals two.

Total arsenic in urine: palladium-persulfate vs nickel as a matrix modifier for graphite furnace atomic absorption spectrophotometry

We evaluated the effectiveness of nickel and palladium with or without added potassium persulfate as matrix modifiers for the determination of total arsenic in urine. Complete recovery of pure aqueous solutions of As(III), As(V), cacodylic acid (DMA), monomethylarsinic acid (MMA), and o-arsanilic acid was attained by using both nickel and palladium modifiers. Combined arsenobetaine and arsenocholine (so-called fish arsenic), extracted from a certified control material of dogfish muscle (DORM-1), were completely recovered with Pd-S2O8 matrix modification, but not with nickel. Excellent agreement with target values for arsenic in urines from the Centre de Toxicologie du Quebec, supplied by the Interlaboratory Comparison Program, was attained irrespective of the arsenic source when we used Pd-S2O8 as the matrix modifier.

On-line photo-oxidation for the determination of organoarsenic compounds by atomic-absorption spectrometry with continuous arsine generation

A method has been developed for on-line conversion of organoarsenicals into arsenate, which is readily detected by atomic-absorption spectrometry with continuous arsine generation. The photoreactor consists of a mercury lamp wrapped with 5 m of PTFE tubing (0.5 mm i.d.). The photo-oxidation conditions were optimized, with a flow-injection analysis procedure, for arsenobetaine, monomethylarsonic acid, dimethylarsinic acid, o-arsanilic acid, and phenylarsonic acid, all organoarsenicals of biological and environmental importance. Solutions were continuously pumped at a flow-rate of 2.0 ml/min and combined with a stream of potassium persulfate (flow-rate 0.6 ml/min) before entering the photo-reactor. With reactor dwell times of 36 sec, conversion efficiencies for these compounds were above 95% under these conditions. Interfacing of this flow-through conversion and detection system with a chromatographic inlet permits real-time analysis of mixtures of these organoarsenic compounds, in a manner suitable for environmental or biomedical samples.

Diorganotin(IV) Derivatives of Ethyl 3-[(o-Arsono-phenyl)imino]butyrate and N-(1-Methyl-3-oxobutylidene)-o-arsanilic Acid

Abstract Ten complexes of diorganotin(IV) have been prepared with two Schiff bases, (i) ethyl 3-[(o-arsono-phenyl)imino]butyrate (SB1H3) and (ii) N-(1-methyl-3-oxobutylidene)-o-arsanilic acid (SB2H3), in 1:1 molar ratio. All complexes are polymeric in nature in the solid state. The enolic OH does not take part in bond formation to tin(IV). The ester C=O of SB1H3 does not take part in coordination. An As=O → Sn inter-molecular bond is present in all the complexes as revealed by IR spectra. A five-coordinate distorted trigonal bipyramidal structure is suggested for all the complexes.

Diorganotin (IV) Derivatives of a New Schiff Base Having Two AsO3H2Groups

Abstract A New Schiff base, N-(1, 4-dimethylbutylidene)-bis-o-arsanilic acid, [o-AsO3H2-C6H4N[dbnd]C(CH3)CH2-]2.H2O (H4SB).H2O has been isolated by the reaction of o-arsanilic acid with acetonylacetone and has been characterized by elemental analysis, IR studies and molecular weight determination. Complexes of the formula (R2Sn)2SB (R = Me, Et, n-Bu and n-Oct; SB is the tetraanion of H4SB) have been prepared by reacting diorganotin(IV) oxides with the Schiff base in 2:1 molar ratio. All the complexes are polymers and insoluble in common organic solvents. A five-coordinate, trans trigonal bipyramidal structure with intermolecular coordination from the oxygen of the As[dbnd]O group is suggested.

Spectrophotometric determination of osmium with o-arsanilic acid

Spectrophotometric determination of osmium with o-arsanilic acid

Spectro photometric determination of bromate with o-arsanilic acid

o-Arsanilic acid reacts with bromate ions in dilute acid solution and forms a reddish-brown color which is suitable for the spectrophotometric determination of bromate. The reaction has a sensitivity of 0.05 μg BrO 3 - per cm2 for log I o l = 0.001 and obeys Beer's law up to 50 p.p.m.The standard deviation for the color development (387 p.p.m. brornate) is 0.95%, and 0.52% in the determination of bromate in salt solutions. Optimum analytical conditions for the reaction have been established and a procedure for the spectrophotometric determination of bromate is given.