A facile four-component tandem protocol for the synthesis of novel 2,6-diaryl-2,3-dihydro-1H-pyridin-4-ones

A one-pot, four-component reaction of 1-(phenylsulfinyl)- or 1-(4-chlorophenylsulfinyl)propan-2-one, aromatic aldehydes and ammonium acetate in a 1:2:1 molar ratio affords a series of new 2,6-diaryl-2,3-dihydro-1H-pyridin-4-ones. This reaction proceeds presumably via a double Mannich reaction-elimination tandem sequence.     

Efficient synthesis of carbohydrate thionolactones

Carbohydrate thionolactones may be efficiently synthesized from the corresponding 1-thio sugars via a two-step procedure involving formation of a glycosyl phenylthiosulfinate by treatment with either phenylsulfinyl chloride or 1-(phenylsulfinyl)piperidine (BSP), and subsequent thermal elimination in toluene.     

Enantiodivergent Syntheses of (R)- and (S)-3,5-Dimethylcyclohex-2-en-1-ones from (R)-Pulegone

R-(+)-pulegone (1) is transformed to (R)-5-methyl-2-(phenylsulfinyl)cyclohexanone (5) (65%, 3 steps). Sulfoxide 5 is converted to R-(-)-3,5-dimethylcyclohex-2-en-1-one (4) (53%, 4 steps) and S-(+)-4 (26%, 3 steps).     

Polycyclic 2H-Pyran Derivatives by Intramolecular Hetero-Diels-Alder Reactionsof a-Sulfur-Substituted a,b-UnsaturatedCarbonyl Compounds

 Reaction of 1-(phenylsulfenyl)-, 1-(phenylsulfinyl)-, and 1-(phenylsulfonyl)-2- propanones as well as 2-(phenylsulfonyl)-acetophenone with 2-(3-methyl-2-butenyloxy)- and 2-((E)-3-phenyl-2-propenyloxy)-benzaldehydes yielded the corresponding Knoevenagel condensation products. The latter compounds underwent intramolecular cycloadditions affording cis-fused 2H-pyran derivatives as the major products.     

Polycyclic 2H-Pyran Derivatives by Intramolecular Hetero-Diels-Alder Reactionsof a-Sulfur-Substituted a,b-UnsaturatedCarbonyl Compounds

Summary.  Reaction of 1-(phenylsulfenyl)-, 1-(phenylsulfinyl)-, and 1-(phenylsulfonyl)-2- propanones as well as 2-(phenylsulfonyl)-acetophenone with 2-(3-methyl-2-butenyloxy)- and 2-((E)-3-phenyl-2-propenyloxy)-benzaldehydes yielded the corresponding Knoevenagel condensation products. The latter compounds underwent intramolecular cycloadditions affording cis-fused 2H-pyran derivatives as the major products. Received June 29, 2000. Accepted July 18, 2000     

Synthesis, characterization and luminescence study of dialkyl[1-arylmethyleneimino-2-naphthonato]gallium complexes: Crystal structure of dimethyl[1-(2-pridyl) methyleneimino-2-naphthonato]gallium

Eight dialkylgallium complexes of type R₂GaL [(M = Me, L = 1-(2-pyridyl)methyleneimino-2-naphthonato (1), M = Et, L = 1-(2-pyridyl)methyleneimino-2-naphthonato (2), M = Me, L = 1-phenylmethyleneimino-2-naphthonato (3), M = Et, L = 1-phenylmethyleneimino-2-naphthonato (4), M = Me, L = 1-(p-methoxylphenyl)methyleneimino-2-naphthonato (5), M = Me, L = 1-(3,4-dimethoxylphenyl)methyleneimino-2-naphthonato (6), M = Me, L = 1-naphthylmethyleneimino-2-naphthonato (7), M = Me, L = 1-naphthylmethyleneimino-2-naphthonato (8)) have been synthesized by reaction of trialkylgallium with appropriate 1-arylmethyleneimino-2-naphthols. The complexes have been characterized by elemental analysis, ¹H NMR, IR and mass spectrometry. Structure of dimethyl[1-(2-pyridyl)methyleneimino-2-naphthonato]gallium (1) has been determined by X-ray single crystal analysis. Ga atom is five coordinate in the structure. Photoluminescent properties have been measured. The maximum emission wavelengths are in the range of 358 and 412 nm with the intensity of 13-325 a.u. The electroluminescent properties of 3, 5, 7 and 8 have been measured. The maximum emission wavelengths are in the range of 450 and 480 nm.     

Evaluation of alternate lines of Fe for sequential multi-element determination of Cu, Fe, Mn and Zn in soil extracts by high-resolution continuum source flame atomic absorption spectrometry

The usefulness of the secondary line at 252.744 nm and the approach of side pixel registration were evaluated for the development of a method for sequential multi-element determination of Cu, Fe, Mn and Zn in soil extracts by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). The influence of side pixel registration on the sensitivity and linearity was investigated by measuring at wings (248.325, 248.323, 248.321, 248.329, and 248.332 nm) of the main line for Fe at 248.327 nm. For the secondary line at 252.744 nm or side pixel registration at 248.325 nm, main lines for Cu (324.754 nm), Mn (279.482 nm) and Zn (213.875 nm), sample flow-rate of 5.0 mL min⁻¹ and calibration by matrix matching, analytical curves in the 0.2-1.0 mg L⁻¹ Cu, 1.0-20.0 mg L⁻¹ Fe, 0.2-2.0 mg L⁻¹ Mn, 0.1-1.0 mg L⁻¹ Zn ranges were obtained with linear correlations better than 0.998. The proposed method was applied to seven soil samples and two soil reference materials (IAC 277; IAC 280). Results were in agreement at a 95% confidence level (paired t-test) with reference values. Recoveries of analytes added to soil extracts containing 0.15 and 0.30 mg L⁻¹ Cu, 7.0 and 14 mg L⁻¹ Fe, 0.60 and 1.20 mg L⁻¹ Mn, 0.07 and 0.15 mg L⁻¹ Zn, varied within the 94-99, 92-98, 93-101, and 93-103% intervals, respectively. The relative standard deviations (n = 12) were 2.7% (Cu), 1.4% (Fe - 252.744 nm), 5.7% (Fe - 248.325 nm), 3.2% (Mn) and 2.8% (Zn) for an extract containing 0.35 mg L⁻¹ Cu, 14 mg L⁻¹ Fe, 1.1 mg L⁻¹ Mn and 0.12 mg L⁻¹ Zn. Detection limits were 5.4 μg L⁻¹ Cu, 55 μg L⁻¹ Fe (252.744 nm), 147 μg L⁻¹ Fe (248.325 nm), 3.0 μg L⁻¹ Mn and 4.2 μg L⁻¹ Zn.     

Sequential injection lab-on-valve simultaneous spectrophotometric determination of trace amounts of copper and iron

A sequential injection (SI) method in a lab-on-valve (LOV) format for simultaneous spectrophotometric determination of copper and iron has been devised. The detection chemistry is based on the complex formation of 2-(5-bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]aniline (5-Br-PSAA) with copper(II) and/or iron(II) at pH 4.6. Copper(II) reacts with 5-Br-PSAA to form the complex which has an absorption maximum at 580 nm but iron(III) does not react. In the presence of a reducing agent only iron(II)-5-Br-PSAA complex is formed and detected at 558 nm. Under the optimum experimental conditions, the determinable ranges are 0.1-2 mg l⁻¹ for copper and 0.1-5 mg l⁻¹ for iron, respectively, with a sampling rate of 18 h⁻¹. The limits of detection are 50 μg l⁻¹ for copper and 25 μg l⁻¹ for iron. The relative standard deviations (n = 15) are 2% for 0.5 mg l⁻¹ copper and 1.8% for 0.5 mg l⁻¹ iron when determined in standard solutions. The recoveries range between 96 and 105% when determining 0.25-2 mg l⁻¹ of copper and 0.2-5 mg l⁻¹ of iron in artificial mixtures at copper/iron ratios of 1:10 to 5:1. The proposed SI-LOV method is successfully applied to the simultaneous determination of copper and iron in multi-element standard solution and in industrial wastewater samples.     

Construction of a new Cu2+ coated wire ion selective electrode based on 2-((2-(2-(2-(2-hydroxy-5-methoxybenzylidene amino)phenyl)disufanyl)phenylimino)methyl)-4-methoxyphenol Schiff base

In this article a new coated platinum Cu²⁺ ion selective electrode based on 2-((2-(2-(2-(2-hydroxy-5-methoxybenzylideneamino)phenyl)disufanyl)phenylimino) methyl)-4-methoxyphenol Schiff base (L₁) as a new ionophore is described. This sensor has a wide linear range of concentration (1.2 × 10⁻⁷-1.0 × 10⁻¹ mol L⁻¹) and a low detection limit of 9.8 × 10⁻⁸ mol L⁻¹of Cu(NO₃)₂. It has a Nernstian response with slope of 29.54 ± 1.62 mV decade⁻¹ and it is applicable in the pH range of 4.0-6.0 without any divergence in potentioal. The coated electrode has a short response time of approximately 9 s and is stable at least for 3.5 months. The electrode shows a good selectivity for Cu²⁺ ion toward a wide variety of metal ions. The proposed sensor was successfully applied for the determination of Cu²⁺ ion in different real and environmental samples and as indicator electrode for potentiometric titration of Cu²⁺ ion with EDTA.     

Synthesis,characterization and ethylene oligomerization and polymerization of 2-(1H-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridylchromium chlorides

A series of N^N^N tridentate chromium complexes (C1–C6) bearing 2-(1H-2-benzimidazolyl)-6-(1-(arylimino)ethyl)pyridine derivatives was synthesized and characterized by elemental and spectroscopic analysis along with single-crystal X-ray crystallography. X-ray crystallographic analyses reveal chromium complex C1 as a distorted six-coordinated octahedral geometry. On treatment with modified methylaluminoxane (MMAO), the chromium complexes exhibited high activities for ethylene oligomerization (up to 1.50 × 10⁶ g mol⁻¹ (Cr) h⁻¹) and polymerization (up to 2.06 × 10⁶ g mol⁻¹ (Cr) h⁻¹) at 10 atm ethylene pressure. Various reaction parameters were investigated in detail, and less steric hindrance and electron-withdrawing substituents of ligands enhance the catalytic activities of their chromium complexes.     

Simultaneous determination of 11 drugs belonging to four different groups in human urine samples by reversed-phase high-performance liquid chromatography method

A new, accurate, sensitive and fast reversed-phase high-performance liquid chromatography (RP-HPLC) as an analytical method for the quantitative determination of 11 drugs in human urine was worked out, optimized and validated. The objects of analysis were imipenem (IMP), paracetamol (PAR), dipyrone (DPR), vancomycin (VCM), amikacin (AMK), fluconazole (FZ), cefazolin (CFZ), prednisolone (PRE), dexamethasone (DEX), furosemide (FUR) and ketoprofen (KET) belonging to four different groups (antibiotics, analgesic, demulcent and diuretic). For HPLC analysis, diode array (DAD) and fluorescence (FL) detectors were used. The separation of analyzed compounds was conducted by means of a LiChroCART^® Purospher^® C₁₈e (125 mm × 3 mm, particle size 5 μm) analytical column with LiChroCART^® LiChrospher^® C₁₈ (4 mm × 4 mm, particle size 5 μm) pre-column with gradient elution. Analyzed drugs were determined within 20 min. The mobile phase was comprised of various proportions of methanol, acetonitrile and 0.05% trifluoroacetic acid in water. AMK was separated and determined from human urine using ortho-phthaldialdehyde-3-mercaptopropionic acid (OPA-3-MPA) as a fluorescent reagent by RP-HPLC-FL. The following retention times for drugs IMP, PAR, DPR, VCM, AMK, FZ, CFZ, PRE, DEX, FUR and KET in human urine were found: 4.01 min, 4.86 min, 6.71 min, 8.14 min, 9.46 min, 10.01 min, 10.90 min, 13.34 min, 14.06 min, 16.03 min and 18.98 min, respectively. Excellent linearity was obtained for compounds in the range of concentration: 0.35-42 μg ml⁻¹, 0.5-45 μg ml⁻¹, 4.5-38 μg ml⁻¹, 0.25-25 μg ml⁻¹, 0.5-35 μg ml⁻¹, 0.25-22 μg ml⁻¹, 0.03-52 μg ml⁻¹, 0.15-25 μg ml⁻¹, 0.25-28 μg ml⁻¹, 0.05-18 μg ml⁻¹ and 0.15-35 μg ml⁻¹ for IMP, PAR, DPR, VCM, AMK, FZ, CFZ, PRE, DEX, FUR and KET, respectively. The limits of detection (LOD) and limits of quantification (LOQ) for analyzed drugs were calculated in all cases and recovery studies were also performed. Ten human urine samples obtained from patients treated in hospital have been tested. In analyzed samples, one or more drugs from the 11 examined drugs were detected. The concentrations of examined drugs in urine samples ranged between: 1.5-12 μg ml⁻¹ of PAR, 5.2-11.5 μg ml⁻¹ of DPR, 0.13-9.5 μg ml⁻¹ of CFZ and 0.1-8 μg ml⁻¹ of FUR. This method can be successfully applied to routine determination of all these drugs in human urine samples.     

Simultaneous determination of fluorophores with overlapped spectra by sequential injection analysis coupled to variable angle scanning fluorescence spectrometry and multivariate linear regression algorithms

An automated and versatile sequential injection spectrofluorimetric procedure for the simultaneous determination of multicomponent mixtures in micellar medium without prior separation processes is reported. The methodology is based upon the segmentation of a sample slug between two different buffer zones in order to attain both an improvement of sensitivity and residual minimization for the whole species. Resolution of overlapping fluorescence profiles is achieved using a variable angle scanning technique coupled to multivariate least-squares regression (MLR) algorithms at both sample edges.The potentialities of the described methodology are illustrated with the spectrofluorimetric determination of four widespread pesticides with different acid-base properties; viz. carbaryl (CBL) (1-naphthyl-N-methylcarbamate), fuberidazole (FBZ) (2-(2′-furyl)benzimidazole), thiabendazole (TBZ) (2-(4′-thiazolyl)benzimidazole) and warfarin (W) (3-α-acetonylbenzyl)-4-hydroxycoumarin). Detection limits at the 3σ level were 3.9, 0.02, 0.03 and 10 μg l⁻¹ for CBL, FBZ, TBZ and W, respectively at the maximum sensitivity pH. Dynamic ranges of 13-720 μg l⁻¹ CBL, 0.10-14 μg l⁻¹ FBZ, 0.19-60 μg l⁻¹ TBZ and 0.05-5 mg l⁻¹ W were achieved. Relative standard deviations (n=10) were 0.2% for 100 μg l⁻¹ CBL and 2.4 μg l⁻¹ FBZ, 0.7% for 8 μg l⁻¹ TBZ and 1.0% for 1 mg l⁻¹ W. The proposed automated methodology, which handles 17 samples/h, was validated and applied to spiked real water samples with very satisfactory results.     

Mineral content and botanical origin of Spanish honeys

Eleven elements (Zn, P, B, Mn, Mg, Cu, Ca, Ba, Sr, Na and K) were determined by inductively plasma coupled spectrometry in 40 honey samples from different places of Spain and four different botanical origins: Eucalyptus (Eucalyptus sp.), Heather (Erica sp.), Orange-blossom (Citrus sinensis) and Rosemary (Rosmarinus officinalis). K, Ca and P show the higher levels with average concentrations ranged between 434.1-1935 mg kg⁻¹ for K; 42.59-341.0 mg kg⁻¹ for Ca and 51.17-154.3 mg kg⁻¹ for P. Levels of Cu (0.531-2.117 mg kg⁻¹), Ba (0.106-1.264 mg kg⁻¹) and Sr (0.257-1.462 mg kg⁻¹) are the lowest in all honey samples. Zn (1.332-7.825 mg kg⁻¹), Mn (0.133-9.471 mg kg⁻¹), Mg (13.26-74.38 mg kg⁻¹) and Na (11.69-218.5 mg kg⁻¹) concentrations were found strongly dependent on the kind of botanical origin.Results were submitted to pattern recognition procedures, unsupervised methods such as cluster and principal components analysis and supervised learning methods like linear discriminant analysis in order to evaluate the existence of data patterns and the possibility of differentiation of Spanish honeys from different botanical origins according to their mineral content. Cluster analysis shows four clusters corresponding to the four botanical origins of honey and PCA explained 71% of the variance with the first two PC variables. The best-grouped honeys were those from heather; eucalyptus honeys formed a more dispersed group and finally orange-blossom and rosemary honeys formed a less distinguishable group.     

Production and characterization of a broad-specificity polyclonal antibody for O,O-diethyl organophosphorus pesticides and a quantitative structure-activity relationship study of antibody recognition

Polyclonal antibody (PAb) with broad-specificity for O,O-diethyl organophosphorus pesticides (OPs) against a generic hapten, 4-(diethoxyphosphorothioyloxy)benzoic acid, was produced. The obtained PAb showed high sensitivity to seven commonly used O,O-diethyl OPs in a competitive indirect enzyme-linked immunosorbent assay (ciELISA) using a heterologous coating antigen, 4-(3-(diethoxyphosphorothioyloxy)phenylamino)-4-oxobutanoic acid. The 50% inhibition value (IC₅₀) was 348 ng mL⁻¹ for parathion, 13 ng mL⁻¹ for coumaphos, 22 ng mL⁻¹ for quinalphos, 35 ng mL⁻¹ for triazophos, 751 ng mL⁻¹ for phorate, 850 ng mL⁻¹ for dichlofenthion, and 1301 ng mL⁻¹ for phoxim. The limit of detection (LOD) met the ideal detection criteria of all the seven OP residues. A quantitative structure-activity relationship (QSAR) model was constructed to study the mechanism of antibody recognition using multiple linear regression analysis. The results indicated that the frontier-orbital energies (energy of the highest occupied molecular orbital, E_HOMO, and energy of the lowest unoccupied molecular orbital, E_LUMO) and hydrophobicity (log of the octanol/water partition coefficient, log P) were mainly responsible for the antibody recognition. The linear equation was log(IC₅₀) = −63.274E_HOMO + 15.985E_LUMO + 0.556 log P − 25.015, with a determination coefficient (r²) of 0.908.     

A reversed-phase high performance liquid chromatography coupled with resonance Rayleigh scattering detection for the determination of four tetracycline antibiotics

A new reversed-phase high performance liquid chromatography with resonance Rayleigh scattering detection (HPLC-RRS) was developed for simultaneous separation and determination of four tetracycline antibiotics (TCs). A good chromatographic separation among the compounds was achieved using a Synergi Fusion-RP column (150 mm × 4.6 mm; 4 μm) and a mobile phase consisting of methanol-acetonitrile-oxalic acid (5 mM) at the flow rate of 0.8 mL min⁻¹. Column temperature was 30 °C. The RRS signal was detected at λ_ex = λ_em = 370 nm. The recoveries of sample added standard ranged from 95.3% to 103.5%, and the relative standard deviation was below 2.79%. A detection limit of 2.12-5.12 μg mL⁻¹ was reached and a linear range was found between peak height and concentration in the range of 10.36-518.0 μg mL⁻¹ for oxytetracycline (OTC), 12.11-605.5 μg mL⁻¹ for tetracycline (TC), 11.79-589.5 μg mL⁻¹ for chlortetracycline (CTC) and 10.32-516.0 μg mL⁻¹ for doxycycline (DC). The linear regression coefficients were all above 0.999. The method has been applied successfully to the determination of OTC, TC, CTC, DC in pharmaceutical formulations and in honey. The method was simple, rapid and showed a better linear relation and high repeatability.     

Preparative isolation and purification of isobenzofuranone derivatives and saponins from seeds of Nigella glandulifera Freyn by high-speed counter-current chromatography combined with gel filtration

Although the medicinal plant and food Nigella glandulifera Freyn has been researched for decades, isobenzofuranones have never been isolated before. Two isobenzofuranone derivatives and two saponins were successfully separated and purified from seeds of N. glandulifera Freyn by high-speed counter-current chromatography (HSCCC) with the optimized two-phase solvent system, n-hexane-ethyl acetate–methanol–water (7:3:5:5, v/v). Salfredin B₁₁ (22.1 mg, HPLC purity 95.3%), 5, 7-dihydroxy-6-(3-methybut-2-enyl) isobenzofuran-1(3H)-one (18.9 mg, HPLC purity 97.3%) and crude sample 2 (555 mg) were separated from 600 mg of ethyl acetate extract of N. glandulifera Freyn. Following a cleaning-up step by chromatography on Sephadex LH-20, hederagenin (12 mg) and 3-O-[β-d-xylopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosyl]-hederagenin (45 mg) were separated from sample 2. All of the fractions before peak II were collected and subjected to a Sephadex LH-20 column and eluted by methanol, two of triterpene saponins (12 mg of hederagenin and 45 mg of 3-O-[β-d-xylopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosyl]-hederagenin) were isolated. The structures of peak fractions were identified by IR, electron ionization MS, ¹H NMR and ¹³C NMR. 5, 7-Dihydroxy-6-(3-methybut-2-enyl) isobenzofuran-1(3H)-one was isolated for the first time from higher plant and salfredin B11 was isolated for the first time in this plant.     

An automated system for liquid-liquid extraction based on a new micro-batch extraction chamber with on-line detection: Preconcentration and determination of copper(II)

An automated system to perform liquid-liquid extraction is proposed, in which the effective mixture (the intimate contact) between the aqueous phase and the organic phase, as well as the separation of the phases, are carried out in a micro-batch glass extraction chamber. Sample, reagents and organic solvent are introduced into the glass extraction chamber by a peristaltic pump using air as carrier. The detection of the extracted species from the aqueous phase is made in a small volume (120-150 μl) of isobutyl methyl ketone (MIBK). The system allows enrichment factors of 2-10-fold. The proposed automatic system was evaluated for Cu(II) extraction based on complex formation between copper(II) and 1-(2′-pyridylazo)naphthol (PAN) in MIBK. When a volumetric ration of 2:1 (aqueous:organic) was implemented, copper was detected in the concentration range of 100-1600 μg l⁻¹ (r = 0.9995) with a relative standard deviation of 2% (200 μg l⁻¹, n = 5) and a detection limit of 20 μg l⁻¹. The analytical curve was linear over the concentration range 25-500 μg l⁻¹ (r = 0.9994) when a volumetric ratio of 10:1 was employed. With this ratio, the detection limit was 5.0 μg l⁻¹ and the relative standard deviation was 6% (50 μg l⁻¹, n = 5).     

Study on the resonance Rayleigh scattering spectra of the interactions of palladium (II)-cephalosporins chelates with 4,5-dibromofluorescein and their analytical applications

In pH 2.8-3.8 BR buffer medium, the third generation cephalosporin antibiotics (TGCs) such as ceftazidime (CZD), ceftriaxone (CTRX), cefoperazone (CPZ), and cefotaxime (CFTM) react with palladium(II) (Pd(II)) to form 1:2 yellowish-brown cationic chelates, which further react with 4, 5-dibromofluorescein (DBF) to form 1:3 brown ion-association complexes. As a result, not only the spectra of absorption and fluorescence are changed, but also the resonance Rayleigh scattering (RRS) is enhanced greatly and the new RRS spectra are observed. The four TGCs products have similar spectral characteristics and their maximum RRS wavelengths are all located at 291 nm. The quantitative determination ranges and the detection limits of the four TGCs are 0.0065-1.0 μg mL⁻¹ and 2.0 ng mL⁻¹ for CZD, 0.0070-1.1 μg mL⁻¹ and 2.2 ng mL⁻¹ for CTRX, 0.0090-1.6 μg mL⁻¹ and 2.7 ng mL⁻¹ for CPZ, and 0.014-2.2 μg mL⁻¹ and 4.2 ng mL⁻¹ for CFTM, respectively. The optimum conditions of the reactions and the effects of foreign substances are investigated, and the composition of ion-association complexes is discussed also. Based on the ion-association reaction, a highly sensitive, simple and rapid method has been proposed to the determination of TGCs.     

Determination of total arsenic and toxicologically relevant arsenic species in fish by using electrothermal and hydride generation atomic absorption spectrometry

A scheme for the determination of total As by electrothermal atomic absorption spectrometry (ETAAS) and the sum of toxicologically relevant arsenic species (As(III), As(V), monomethylarsonate (MMA) and dimethylarsinate (DMA) using hydride generation AAS (HGAAS) in fish samples was developed. Simple and fast microwave assisted extraction in tetramethylammonium hydroxide (TMAH, 0.075% m / v) or in water-methanol mixture (80 + 20 v / v) for 20 min is proposed for quantitative leaching of arsenic species from fish tissue. Total As was measured by ETAAS directly in the TMAH extract under optimal instrumental parameters (pyrolysis temperature 1400 °C and atomization temperature 2000 °C) with Pd as modifier ensuring thermal stabilization and isoformation of all extracted arsenic species. The analytical features of the method are as follows: limit of detection (LOD) 0.45 μg g^− 1 (dry wt.), within-run and between-run precision in the range 4-8% and 5-12%, respectively, for arsenic contents 0.5-30 μg g^− 1 and recoveries 98-102%. The sum of toxicologically relevant arsenic species (As(III) + As(V) + MMA + DMA) was determined by flow injection HGAAS directly from the TMAH extract or water-methanol mixture and trapping of arsines onto Zr-Ir coated graphite tube followed by ETAAS measurement. l-cysteine is used as reagent for leveling off responses of different arsenic species in the presence of TMAH or water-methanol mixture. The LODs achieved are 0.0038 and 0.0031 μg g^− 1 (dry wt.), respectively, for fish extracts in TMAH and in water-methanol mixture. Within-batch and between-batch RSDs are in the range 3-5% and 4-7% for arsenic contents of 0.009-0.25 μg g^− 1 (dry wt.) for TMAH extracts and 2-4% and 3-6% for methanol water extracts, respectively. Selective reaction media for generation of respective hydrides from arsenic species were recommended for further speciation purposes in methanol-water extracts, viz. citrate buffer (pH 5.2) for the determination of As(III), 0.2 mol L^− 1 acetic acid for the determination of As(III) + DMA and 7 mol L^− 1 hydrochloric acid for the determination of inorganic As(III) + As(V). LODs are 0.0035, 0.0051 and 0.0046 μg g^− 1 (dry wt.) for As(III), DMA and As(V). The relative standard deviation is 4-8% for three arsenic species at As levels of 0.009-0.5 μg g^− 1 (dry wt.). The accuracy of the proposed speciation scheme is confirmed by the analysis of certified reference materials.