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1.
A method for the reversed-phase liquid chromatographic separation and determination of V(V), Nb(V) and Ta(V) as 2-(5-nitro-2-pyridylazo)-5 diethylaminophenol (5-NO2-PADAP) complexes is reported. The metal complexes were eluted in 9 min with a mobile phase of methanol-water (54 : 46, v/v) containing 10 mmol L–1 acetate buffer (pH 3.0) on an ODS column. The detection limits for V, Nb and Ta were 0.09, 0.13 and 1.41 ng mL–1, respectively, with S/N=3. The analysis of a reference sample of a mineral is discussed. The results corresponded to the certified values, and recoveries of 98.3–101.4% have been obtained.  相似文献   

2.
Zusammenfassung Eine empfindliche und selektive spektralphotometrische Kobaltbestimmung (<0,9 g ml–1) ist mit 2-(5-Brom-2-pyridylazo)-5-diethylaminophenol (5-Brom-PADAP) auf Grund des kinetisch stabilen Co(III)L 2 -Chelates möglich, das nach seiner Bildung bei pH 7 (Ammoniumacetat) in Gegenwart von 0,1% Triton X-100, 5,10–3 M Ammoniumperoxodisulfat und 10% (v/v) Dimethylformamid (auch nach Zugabe von 1,25 M H2SO4, 1,80 M HNO3 oder auch 0,1–0,01 M EDTA) stabil ist. Eine Reihe von 5-Brom-PADAP-Chelaten störender Ionen werden dabei zersetzt. V(V), Hg2+, Ni2+, Cu2+, Pd2+ können stören. Die Kobaltbestimmung in Cyanocobalamin und auch Trinkwasser ist auf diesem Wege möglich. Die Fehler lagen im Bereich von — 3 bis — 7 % (1,8–9 g Co/l).Herrn Prof. Dr. F. Umland, Westfälische Universität, Münster/Westfalen, sind wir für das 5-Brom-PADAP mit herzlichem Dank verpflichtet.  相似文献   

3.
A flow injection method using 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol-(Nitro-PAPS) as a new chromogenic reagent is presented for sensitive and rapid determination of vanadium. Nitro-PAPS reacts with vanadium(V) in weakly acidic medium to form a water soluble complex of molar absorptivity of 8.0 × 104L mol–1 cm–1 at 592 nm (maximum absorption wavelength), which permits the straightforward application of a flow injection system to the sensitive determination of vanadium. Under the optimum conditions established, a linear calibration graph was obtained in the range 1–120 ng mL–1. The relative standard deviation for 60 ng mL–1 vanadium was 2.2% (n = 5) and the limit of detection was 1 ng mL–1. The sample throughput is about 40 h–1. Most inorganic and organic anions examined did not interfere even at concentrations of 3000–6000 times of vanadium. Interference from cobalt(II), copper(II) and nickel(II) at 200ng mL–1 levels can be overcome by the addition of N-(dithio-carboxy)sarcosine. The recoveries for each 20 and 10 ng mL–1 vanadium added to the river water were 98 and 97%, respectively.The authors express their thanks to Miss Miho Suzuki and Miss Hiroyo Yamada for their experimental assistance in part.  相似文献   

4.
Ionophoric, extraction, acidic and hydrophobic properties of 3-(4-tolylazo)phenylboronic acid (TAPBA) were studied. Determined Kd value equals to 36±2, pKa equals to 8.6±0.5. TAPBA extracts dobutamine from water into chloroform and transports it across a bulk chloroform membrane. The recovery is 83% (pH=7.5), the transport rate – (6.5±0.5)×10−7 mol/h. 1H and 13C NMR data confirm the formation of an 1:1 complex between arylboronic acid and catecholamine. TAPBA was used as electrode-active component of plasticized membrane electrodes with cationic and anionic responses to catecholamines and phenolic acids, respectively. For the diethyl sebacate-plasticized membrane, a slope of electrode function to dobutamine is 56±2 mV/decade; the detection limit is 1.3×10−5 mol/l; the linear range – 5×10−5–1×10−2 mol/l; the working pH-range – 4.8–7.6; the response time – 5–10 s. ISE gives incomplete cationic function to less lipophilic catecholamines. The membrane with cationic additive shows an anionic response to caffeic acid in wide pH range.  相似文献   

5.
The corresponding N1-(2-furoylmethyl) and N1-(5-nitro-2-furoylmethyl) derivatives of uracil and its 5-substituted derivatives were obtained by the reaction of 2-bromo- and 5-nitro-2-bromoacetylfurans with uracil, 5-fluorouracil, and thymine. The structures of these compounds as N1-substituted uracils were proved by a study of the UV spectra at various pH values. The computational method of expanding the UV spectra into individual bands was used.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1268–1270, September, 1971.  相似文献   

6.
A new chromogenic reagent, 2-(2-quinolylazo)-5-Dimethylaminophenol (QADMAP) was synthesized, and a sensitive, selective, and rapid method was developed for the determination of the μg/L level of silver ions. The method is based on the rapid reaction of silver(I) with QADMAP and the solid phase extraction of the colored chelate using a C18 cartridge. The QADMAP reacts with Ag(I) in the presence of a citric acid-sodium hydroxide buffer solution (pH 5.0) and a sodium dodecyl sulfonate (SDS) medium to form a violet chelate of molar ratio 1 : 2 (silver to QADMAP). This chelate was enriched by solid phase extraction with C18 cartridge, and the retained chelate was eluted from the cartridge using ethanol (with 1% acetic acid). In the ethanol medium (with 1% acetic acid), the molar absorptivity of the chelate was 1.25 × 105 L mol−1 cm−1 at 584 nm. Beer’s law was obeyed in the range 0.01–0.6 μg/mL. The relative standard deviation for eleven replicate samples of 0.01 μg/mL was 1.86%. The detection limit is 0.02 μg/L in the original samples. The method was applied to the determination of μg/L levels of silver ions in water with good results.__________From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 6, 2005, pp. 566–570.Original English Text Copyright © 2005 by Huang, Yang, Hu, Yin.This article was submitted by the authors in English.  相似文献   

7.
The quantification of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (Mutagen X or MX) in drinking water is difficult due to the low concentration of MX in drinking water, its high sensitivity to pH change, and matrix effects that interfere with the derivatization and analysis. Typically, the quantification of MX involves derivatization by methylation. We present a one-step derivatization procedure for MX using N-methyl-bis-trifluoroacetamide (MBTFA) and analysis by ion trap GC/MS/MS. The new method resulted in a significant reduction in analysis time, and improved detection limits. The abundant and selective ions in the mass spectrum of the trifluoroacylated MX (trifluoroacetic acid-4-chloro-3-dichloromethyl-5-oxo-2-hydro-furan-2-yl ester) allowed for a clear identification and quantification of the compound, with a method detection limit of 7.7 ng L−1, and a limit of quantitation of 24.4 ng L−1. The trifluoroacylated MX was shown to be stable for 30 days in an excess of the derivatization reagent. The new method was applied for the determination of MX in several drinking water samples, with a concentration range from not-detected to 517 ng L−1; these values are comparable to those obtained in previous studies. The development of this new simplified analytical method for MX is an important step forward in the field of disinfection by-product (DBP) research, particularly in light of the recent scientific recognition of halogenated furanones as emerging drinking water contaminants. Increased analytical ability may well be a decisive factor in the monitoring of these disinfection by-products.  相似文献   

8.
The simultaneous determination of vanadium, niobium, and tantalum by reversed-phase high performance liquid chromatography (HPLC) with 2-(2-thiazolylazo)-5-diethylaminophenol (TADAP) as the precolumn chelating reagent has been established. Optimum conditions for the separation, such as the methanol content, the addition of tartaric acid, pH, and the concentration of acetate buffer, were investigated. The metal chelates were eluted in 8 min with a mobile phase of methanol–water (55/45, v/v) containing tartaric acid (0.1%, m/v) and acetate buffer (pH 3.5, 10 mmol/liter) on an ODS column at 568 nm. The detection limits (signal-to-noise RATIO = 3) for V(V), Nb(V), and Ta(V) were 0.16, 0.32, and 1.77 ng/ml, respectively. The proposed method was applied to the analyses of a reference of mineral and synthetic samples. The result was in accord with the certified value, and the recoveries were 98.9–101.8%.  相似文献   

9.
The chemical transformations of 6-[(1-methyl-4-nitro-5-imidazolyl)thio]purine (azathiopurine) —hydrogenation, acetylation, alkylation by lower alkyl halides at positions 7 and 9 of the purine ring, hydrolytic cleavage at the C(6)–S and S–C(5) bonds— were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 372–379, March, 2000.  相似文献   

10.
Zusammenfassung Die relativen Basizitätskonstanten von 5H-Dibenzo(a,h)phenoxazon-(5) (I) (K=3,2 · 10–2), 5H-Dibenzo(a,j)phenoxazon-(5) (II) (K=6,5 · 10–2), 9-(N-1-Naphthylamino)-5H-dibenzo(a,j)phenoxazon-(5) (III) (K=1,12), 9-(N-2-Naphthylamino)-5H-dibenzo(a, j)phenoxazon-(S) (IV) (K=1,22), 9-Anilino-5H-dibenzo(a,j) phenoxazon-(5) (V) (K=1,28) und 9-(p-Tolylamino)-5H-dibenzo(a,j)phenoxazon-(5) (VI) (K=1,45) wurden für das Puffersystem Acetat-Antipyrinperchlorat in wasserfreier Essigsäure bestimmt. Die Verbindungen II, V und VI wurden zur visuellen Indikation von Titrationen schwacher Basen mit Perchlorsäure in wasserfreier Essigsäure benutzt. Mit Indicator II können Basen mit pKa(H2O)-Werten von 2–4 und mit den Indicatoren V und VI stärkere Basen mit pKa(H2O)-Werten von 4–7 bestimmt werden.
Dibenzophenoxazone-(5)-derivatives as neutralisation indicators in non-aqueous acetic acid
The relative basicity constants of 5H-dibenzo(a,h)phenoxazone-(5) (I) (K=3.2×10–2), 5H-dibenzo(a,j)phenoxazone-(5) (II) (K=6.5×10–2), 9-(N-1-naphthylamino)-5H-dibenzo(a,j)phenoxazone-(5) (III) (K=1.12), 9-(N-2-naphthylamino)-5H-dibenzo(a,j)phenoxazone-(5) (IV) (K=1.22), 9-anilino-5H-dibenzo(a,j)phenoxazone-(5) (V) (K=1.28) and 9-(p-tolylamino)-5H-dibenzo(a,j)phenoxazone-(5) (VI) (K=1.45) have been determined with respect to the buffer system antipyrine acetate-antipyrine perchlorate in non-aqueous acetic acid. The compounds II, V and VI were employed for visual indication of titrations of weak bases with perchloric acid in non-aqueous acetic acid. Indicator II is convenient for the titration of bases with pK a (H2O) values 2–4 and indicators V and VI for bases with pKa(H2O) values 4–7.
  相似文献   

11.
Zusammenfassung Eine potentiometrische Methode der titanometrischen Bestimmung von 11-Methylbenzo(a)phenoxazon-(9), Dibenzo(a,j)phenoxazon-(5), Dibenzo(a,h)phenoxazon-(5) und ihrer Derivate mit 0,01-n TiCl3 unter Stickstoffatmosphäre in 1-n Salzsäure wurde ausgearbeitet. Mit Hilfe der Methode der Gemische wurden die formalen Redoxpotentiale von 11-Methylbenzo(a)phenoxazon-(9) und einigen seiner Derivate in 50%igem Äthanol vermessen. Diese Verbindungen haben sich als geeignete visuelle Indikatoren für die titanometrische Bestimmung von Fe3+, Au3+, Cr2O7 2–, VO3 , [Fe(CN)6]3–, insbesondere für die genaue Bestimmung von 1-Nitroso-2-naphthol, p-Nitrosodimethylanilin, p-Nitrosodiäthylanilin, 2,3-Dichlor-1, 4-naphthochinon, 1,2-Naphthochinon-4-natriumsulfonat und 1,4-Naphthochinon erwiesen.
Titanometric Investigation of 11-methylbenzo(a)phenoxazone-(9)- and dibenzophenoxazone-(5)-derivatives
Summary A potentiometric method has been developed for the titanometric determination of 11-methylbenzo(a)phenoxazone-(9), dibenzo(a,j)phenoxazone-(5), dibenzo(a,h)phenoxazone-(5) and their derivatives in 1N hydrochloric acid with 0.01N TiCl3 under an atmosphere of nitrogen. The formal redox potentials were determined (in 50% ethanol) of 11-methylbenzo(a)phenoxazone-(9) and several of its derivatives. These compounds have been found suitable visual indicators for the titanometric determination of Fe3+, Au3+, Cr2O0 2–, VO3 , [Fe(CN)6]3– and especially for the precise determination of 1-nitroso-2-naphthol,p-nitrosodimethylaniline,p-nitrosodiethylaniline, 2,3-dichloro-1,4-naphthoquinone, 1,2-naphthoquinone-4-sodium sulfonic acid, and 1,4-naphthoquinone.
  相似文献   

12.
A spectrophotometric study of the Cd(II) and Cu(II) complex of a new reagent, 2-(5-bromo-2-pyridylazo)-5-diethylamino phenol (5-Br-PADAP) in the presence of polyglycol octylphenyl ether (OP) is presented. A reddish binary complex is formed at pH 9 and shows maximal absorbance at 560 nm with molar absorptivity of 1.16 × 105 · mol−1 · cm−1 liter (Cd), 1.5 × 105 mol−1 · cm−1 · liter (Cu). Beer's law is followed over the range 0.0 to 20 μg cadmium(II) and 0.0–18 μg copper(II). The continuous variation method and molar ratio method showed that the metal ligand ratio is 1:2; ordinarily, most ions do not interfere with the determination and the method can be applied for direct spectrophotometric determination of cadmium(II) and copper(II) in actual samples and the results obtained are satisfactory.  相似文献   

13.
A new sensitive and highly selective method is described for the spectrophotometric determination of microgram amounts of vanadium(V). First, vanadium is isolated by extraction withN-benzoyl-N-phenylhydroxylamine (BPHA) in chloroform from about 4M hydrochloric acid medium. Then, chloroform is evaporated and the residue mineralized with mixture of cone. perchloric and nitric acid. Finally, a colour reaction of vanadium(V) separated with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) in an acetate buffer (pH 4.5) gives a molar absorptivity of 5.48×104l·mol–1·cm–1 at 585 nm. The proposed method was applied for the determination of traces of vanadium in aluminium samples. The results obtained show a good precision and accuracy of the method.  相似文献   

14.
The melting points of anhydrous 1-O-α- -glucopyranosyl- -mannitol, 1-O-α- -glucopyranosyl- -mannitol dihydrate and a new compound, 1-O-α- -glucopyranosyl- -mannitol-ethanol (2/1) were determined using differential scanning calorimetry. The melting onset values were 169.2 (3), 104.3 (18) and 158.7 (9), respectively, and the melting peak values were 171.4 (5), 107.9 (15) and 160.1 (6), respectively. 1-O-α- -glucopyranosyl- -mannitol dihydrate and 1-O-α- -glucopyranosyl- -mannitol-ethanol (2/1) decompose to anhydrous form when heated at slow heating rates.According to TG-FTIR measurements, 1-O-α- -glucopyranosyl- -mannitol-ethanol (2/1) lost its ethanol in the 110–190°C range, and 1-O-α- -glucopyranosyl- -mannitol dihydrate lost its crystal water in the 60–210°C range. After removal of ethanol and crystal water, both decomposed in air totally as carbohydrates usually do, forming lower hydrocarbons with OH-groups, CO2 and H2O.  相似文献   

15.
Monooctyl--(4-carboxyanilino)benzylphosphonic acid (H2L) was investigated as a novel reagent for the extraction and separation of lead(II) and bismuth(III) from nitrate solutions. Stoichiometric ionization constants of H2L in ethanol — water mixtures determined by potentiometric NaOH titration had values pKa1 2.25 and pKa2 4.33. Ethanol and chloroform solutions of H2L followed Beer's law at 300 nm and 296 nm, molar absorptivities being 2.94·104 mol–1·l·cm–1 and 2.85·104 mol–1·l·cm–1, respectively. HNO3 and HCl were also extracted into chloroform solutions containing H2L. Bismuth(III) was quantitatively transferred into the chloroform H2L solution at pH 1, and lead(II) at 3.5. The value of the separation factor DBi/DPb is 160 at pH 1.  相似文献   

16.
The equilibrium extraction behavior of Sm(III), Eu(III) and Dy(III) from aqueous NaClO4 solutions in the pH range of 4–9 at 0.1 M ionic strength into organic solutions of 1-nitroso-2-naphthol (HA) and 1,10-phenanthroline (Phen) has been studied. The equilibrium concentrations of Eu were assayed through the 344 keV photopeak of the152Eu radiotracer used. The concentrations of Sm and Dy were measured by irradiating one mL portions of the organic extract and analyzing the 104 and 108 keV photopeaks of the short-lived neutron activation products,155Sm and165mDy, respectively. Quantitative extraction of Eu with 5×10–2 M HA alone was obtained in the pH range of 6.7–7.8 with n-butanol, 7.4–8.5 with chloroform, 8.0–8.7 with ethyl acetate, 7.7–8.5 with isoamyl alcohol and 6.1–8.0 with methyl isobutyl ketone (MIBK). But, Eu was extracted only to a maximum of 78% and 83% in the pH range of 8.3–8.9 and 7.4–8.1 with carbon tetrachloride and xylene, respectively. The extraction of Sm and Dy were found quantitative in the pH range of 6.3–7.0 and 6.6–7.1, respectively, with 5×10–2 M HA alone in MIBK solutions. The synergistic extraction of Eu was quantitative in the pH range of 6.6–9.8 with chloroform, 7.8–8.9 with ethyl acetate, 7.7–8.5 with isoamyl alcohol and 6.0–9.6 with MIBK when 1×10–2 M each of HA and Phen were employed. Sm and Dy were quantitatively extracted into MIBK solutions containing 5×10–2 M each of HA and Phen in the pH range 6.0–7.5 and 6.1–7.5, respectively. The distribution ratios of these lanthanides (Ln) were determined as a function of pH, and HA and Phen concentrations. The analysis of the data suggests that these Ln are extracted as LnA3 chelates when HA alone is used. In the presence of HA and Phen, both LnA3(Phen) and LnA3(Phen)2 adducts are formed only in the MIBK system while LnA3(Phen) complexes are the predominant ones in all other solvent systems studied. The extraction constants and the adduct formation constants of these complexes have been calculated.  相似文献   

17.
An extremely sensitive stripping voltammetric procedure for low level measurements of platinum (II, IV) or ruthenium (III, IV) is reported. The method is based on the interfacial accumulation of the platinum (II) or ruthenium (III)-1-(2-pyridylazo)-2-naphthol complex on the surface of a hanging mercury drop electrode, followed by the reduction of the adsorbed complex during the cathodic scan. The peak potential was found to be –0.8 V vs. Ag/AgCl electrode and the reduction current of the adsorbed complex ions of platinum (II) or ruthenium (III) was measured by differential pulse cathodic stripping voltammetry. The optimum experimental conditions were: 1.5×10–7 mol/l of 1-(2-pyridylazo)-2-naphthol solution of pH 9.3, preconcentration potential of –0.2 V, accumulation time of 3 min and pulse amplitude of 50 mV with 4 mV s–1 scan rate in the presence of ethanol-water (30% v/v) — sodium sulphate (0.5 mol/l). Linear response up to 6.4 × 10–8 and 5.1 × 10–8 mol/l and a relative standard deviation (at 1.2×10–8 mol/l) of 2.4 and 1.6% (n=5) for platinum (II) and ruthenium (III) respectively were obtained. The detection limits of platinum and ruthenium were 3.2×10–10 and 4.1×10–10 mol/l, respectively. The electronic spectra of the Pt(II) — PAN and Ru(III) — PAN complexes were measured at pH 9.3 and the stoichiometric ratios of the complexes formed were obtained by the molar ratio method. The effects of some interfering ions on the proposed procedure were critically investigated. The method was found suitable for the sub-microdetermination of ruthenium (IV) and platinum (IV) after their reduction to ruthenium (III) and platinum (II) with sulphur dioxide in acid media. The applicability of the method for the analysis of binary mixtures of ruthenium (III) and (IV) or platinum (II) and (IV) has also been carried out successfully. The method is simple, rapid, precise, and promising for the determination of the tested metal ions at micro-molar concentration level.  相似文献   

18.
An extremely potent mutagen, 3-chloro-4(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) is commonly present in chlorinated drinking water. Due to its high mutagenic activity and according to World Health Organization guidelines its concentration should be controlled in drinking waters. Determination of MX is difficult due to ppt levels at which the compound usually exists in drinking waters. Derivatization of MX with 2-propanol is presented as a method which significantly lowers the GC–MS detection level compared to other alcohol derivatization agents.  相似文献   

19.
Summary Cadmium(II) reacts with l-[(5-chloro-2-pyridyl)azo]-2-naphthol (5-C1--PAN) in aqueous solution; the complex can be extracted with chloroform at pH 9–11 to give a red solution with an absorption peak at 566 nm. The colour in chloroform is stable and the system conforms to Beer's law; optimal range in the chloroform layer for measurement at 1.00-cm cells is 0.1–1 ppm cadmium. Common cations and anions do not interfere. Large amounts of some cations can be masked by potassium cyanide, the cadmium cyanide complex being demasked by formaldehyde. The proposed method is one of the most sensitive procedure for the determination of cadmium. The molar absorptivity in the chloroform extract is 6.6· 104 1 mole–1 cm–2 at 566 nm.
Zusammenfassung Cadmium reagiert mit 1-(5-Chlor-2-pyridyl) azo-2-naphthol, 5-C1--PAN, in wäßriger Lösung; der rote Komplex kann bei pH 9–11 mit Chloroform extrahiert werden und hat ein Absorptionsmaximum bei 566 nm. Die chloroformische Lösung ist stabil und entspricht dem Beerschen Gesetz; für die Messung in l-cm-Küvetten eignen sich am besten 0,1–1 ppm Cd. Übliche Ionen stören nicht. Große Mengen einiger Kationen können mit KCN maskiert werden, wahrend [Cd(CN)4]2– von Formaldehyd gespalten wird. Die vorgeschlagene Methode ist eine der empfindlichsten für die Bestimmung von Cd. Die molare Extinktion des chloroformischen Extraktes betragt bei 566 nm 6,6 · 104 1 · mol–1 · cm–2.
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20.
A new complex of a chiral monoaza-crown ether, [R-(-)-2-ethyl-N-benzyl-4,7,10,13-tetraoxa-1-azacyclopentadeceane) NaClO4], has been prepared and studied by x-ray diffraction. The compound crystallizes in space group P21 with cell dimensions a = 9.480(1), b = 15.978(2), c = 15.816(2) Å, = 105.51(1)°, Z = 4. The final R value is 0.055 for 2711 observed reflections and 540 parameters. There are twomolecules in the asymmetric unit labelled A and B. The sodium ion is hexacoordinated. The average values for the Na–-Oeth (etheric) distances are 2.364(6), 2.317(7) Å and the Na–N distances are 2.679(6), 2.611(7) Å; the Na–-O(ClO4) contacts are2.497(7) and 2.257(10) Å, for A and B, respectively.  相似文献   

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