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1.
The synthesis ofo-hydroxybenzenediazoaminoazobenzene (HDAA) is described. Cadmium forms with HDAA in the presence of Triton X-100 a 13 complex, which gives a maximum absorption at 520nm with an apparent molar absorptivity of 1.97 × 1051 · mol–1 · cm–1 in pH 10 borax buffer solution and 1.52 × 1051 · mol–1 · cm–1 in ammoniacal medium. In both media, Beer's law is followed in the range of 0 –10 g of cadmium in 25ml of solution and the coefficients of variation do not exceed 1.5%. A derivative method has been employed to determine cadmium in certain waste water samples without separation.  相似文献   

2.
Zusammenfassung Bor reagiert in Form des Tetrafluoroboratkomplexes mit dem basischen Farbstoff Methylenblau unter Bildung eines mit 1,2-Dichlorethan extrahierbaren Ionenassoziatkomplexes. Die optimalen Bedingungen für die photometrische Bestimmung von Mikromengen Bor werden ermittelt und das vorgestellte Verfahren hinsichtlich Empfindlichkeit, Genauigkeit und kleinster bestimmbarer Menge charakterisiert.Die Borbestimmung ist im Bereich von 0,25–2,5 g Bor mit einer relativen Standardabweichung von 3,8% für 1,0 g Bor möglich. Der molare Extinktionskoeffizient beträgt 665=8,2·1041·mol–1·cm–1, die Nachweisgrenze nach Kaiser 0,125 g Bor.Das Verfahren wurde zur Bestimmung von 10–6 bis 10–5% Bor in folgenden hochreinen Chemikalien eingesetzt: Methanol, Ethanol, Isopropanol, Aceton, Mineralsäuren, Essigsäure, Ammoniak und Wasserstoffperoxid.
Photometric determination of boron in high-purity chemicals
Summary Boron reacts with fluoride to form borofluoride which itself reacts with the basic dye methylene blue forming a complex which can be extracted into 1,2-dichloroethane. Optimum conditions were established for the determination of microamounts of boron by an extraction-photometric method. The procedure presented has been characterized with regard to sensitivity, precision and detection limit.Boron can be determined within a range from 0.25 to 2.5 g with a relative standard deviation s rel=3.8% for 1 g B. The absorptivity is 665=8.2·1041·mol–1·cm–1, the detection limit according to Kaiser was found to be 0.125 g B.The procedure was used to analyse high-purity chemicals (10–6–10–5% B) such as organic solvents, mineral acids, acetic acid, ammonia, hydrogen peroxide etc.
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3.
An extraction and spectrophotometric method for determination of trace amounts of uranium in phosphate fertilizers is described. It is based on the extraction of uranium with trioctylphosphine oxide in benzene and the spectrophotometric determination of uranium with Arsenazo III in buffer-alcoholic medium. The maximum absorbance occurs at 655 nm with a molar absorptivity of 1.2·104 l·mol–1·cm–1. Beer's law is obeyed over the range 0.6–15.0 g·ml–1 of uranium(VI). The proposed method has been applied successfully to the analysis of phosphate fertilizers with phosphate concentrations of 45% P2O5.  相似文献   

4.
Potassium ferrocyanide gives a colour reaction with U(VI), which is suitable for its determination. The complex absorbs in the wavelength range of 390–397 nm. The optimum pH range for colour development was 1.5–3.5. The molar absorptivity was found to be 4.65·103 1·mol–1·cm–1. Most of the anions up to 1000 g did not interfere. The method was made selective by extracting U(VI) first with DOSO from the mixture of interfering cations from 1–2M HNO3 medium and then determining uranium in the back-extracted solution by developing the colour with ferrocyanide. 20 g/10 ml of U(VI) in the final solution could be satisfactorily determined within an RSD of ±2%.  相似文献   

5.
On pulse radiolysis of N2O saturated aqueous solutions of atropine, an optical absorption band (max at 320 nm,e=2.81·103 dm3·mol–1·cm–1) was observed, which is assigned to the product of reaction of OH radicals with the solute. This absorption decayed following second order kinetics with a rate constant of 4.5·108 dm3·mol–1·s–1. The rate constant for the reaction of OH radicals with atropine as estimated by following the build-up kinetics is 2.7·109 dm3·mol–1·s–1. The H atoms also reacted with this compound to produce a transient absorption band behaving similarly to the one observed in the case of reaction with OH radicals. The transient species formed in both cases is assigned to a radical derived by H atom abstraction by H/OH radicals from the parent compound. This radical was unreactive towards 2-mercaptoethanol. e aq was found to react with atropine forming a transient band with max at 310 nm (=3.55·103 dm3·mol–1). Its decay was also second order with a rate constant of 1.64·109 dm3·mol–1·s–1. The bimolecular rate constant for the reaction of e aq with atropine as estimated from the decay of e aq absorption at 720 nm is 3.9·109 dm3·mol–1·s–1. Specific one-electron oxidizing and reducing agents (such as Cl 2 , Tl2+, SO 4 and (CH3)2COH, CO 2 , respectively) failed to oxidize or reduce this compound in aqoues solutions. The radical anion of atropine formed by its reaction with e aq was found to reduce thionine and methyl viologen with bimolecular rate constant of 3.8·109 and 3.2·109 dm3·mol–1·s–1, respectively.  相似文献   

6.
Zusammenfassung Optimale Bedingungen zur photometrischen Bestimmung von Spurengehalten Arsen und Phosphor nebeneinander wurden ermittelt. Die dem Verfahren zugrundeliegende Farbreaktion ist die Umsetzung von in saurer Lösung gebildeter Dodekamolybdatoarsen- bzw.-phosphorsäure mit Hydraziniumsulfat zu Arsen-bzw. Phosphor-Molybdänblau. Auf diese Weise sind Arsengehalte zwischen 1,1 und 10,0 g sowie 0,12 bis 8,0 g Phosphor zu bestimmen. Die Empfindlichkeit der Verfahren beträgt 830=2,0·104l·mol–1·cm–1 für As und 830=2.6·104 l·mol–1·cm–1 für P.Die Bestimmung beider Elemente nebeneinander gelingt dadurch, daß man nach der Summenbestimmung von As und P das Arsen aus der Analysenlösung durch Verflüchtigung als AsBr3 entfernt oder es zu nicht mehr reaktionsfähigem As(III) reduziert. In der nun As-freien Lösung kann der P-Gehalt nach gleichem Verfahren ermittelt werden.Das Verfahren wurde zur Bestimmung von Arsen und Phosphor in hochreinen Chemikalien eingesetzt.
Photometric determination of arsenic and phosphorus in high-purity chemicals
Summary Optimal conditions for the photometric determination of microgram amounts of arsenic and phosphorus are reported. The method bases on the reaction between molybdophosphoric or molybdoarsenic acid respectively, and hydrazinium sulphate to provide heteropoly blue.In this way arsenic can be determined within a range from 1.1 to 10.0 g and phosphorus within a range from 0.12 to 8.0 g. The absorptivities are 830=2.0·104l·mol–1 ·cm–1 for As and 830=2.6·104l·mol·cm–1 for P, respectively.The simultaneous determination of As and P involves at first the determination of the sum of these elements and after reduction of arsenic to As(III) or volatilization as the bromide in a second step the determination of P in the same way.The method has been applied to the determination of arsenic and phosphorus in high-purity chemicals.
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7.
In view ofHammond's warning6 about the Conspiracy of errors, found in the case of low values of equilibrium constants of charge-transfer complexes a case is made out for redetermining the values for the system hexamethylbenzene—2,3-dichloro-1,4-naphthoquinone. Uncertainties in the parameters were estimated using theLiptay 8 matrix procedure. The solvent used was dichloromethane. The following data were obtained at 25°C: vC T = 22,220 cm–1;E A=0.99 eV;K =2599±57 l2·cm–1·mol–2. max= 1020 ± 148 cm–1··1;K=2.55±0.37 l·mol–1; –H=2.7±0.3 kcal·mol–1.With 1 Figure  相似文献   

8.
Spectral studies of morin in aqueous ethanol and other alcohols have been carried out as a function of its concentration and that of ethanol, and the pH of aqueous buffer. The effect of gamma radiations on morin solution in ethanol was also studied as a function of dose in the range of 0.15–2.28 kGy and of morin concentration (10–5–10–4 mole·dm–3). Morin concentration in ethanol solution showed a linear response for G values to a dose of 1.83 kGy. Molar absorption coefficients () for morin in ethanol have been estimated to be 260nm=2.28·104 dm3·mol–1·cm–1 and 291nm=8.22·103 dm3·mol–1·cm–1 for unirradiated and 291 nm=1.75·104 dm3·mol–1·cm–1 for irradiated solutions to a dose of 1.83 kGy.  相似文献   

9.
Zusammenfassung Zur Bestimmung sehr kleiner Arsengehalte kann die Umsetzung von Arsenwasserstoff, der sich bei der Reduktion mit Zink bildet, mit einer Silberdiethyldithiocarbamatlösung in Chloroform in Gegenwart von Brucin herangezogen werden.Das auf dieser Basis ausgearbeitete photometrische Verfahren wurde hinsichtlich Empfindlichkeit, Genauigkeit, kleinster bestimmbarer Menge und Störung durch Fremdionen charakterisiert.Die Arsenbestimmung ist im Bereich von 0,5– 5,0 g As mit einer relativen Standardabweichung von 8,9% für 2,0 g As möglich. Der molare Extinktionskoeffizient beträgt 505=8.5·103l·mol–1·cm–1, die Nachweisgrenze nach Kaiser 0.30 g As. Se(IV), Te(VI), Sb(V) und Thiosulfat stören, zahlreiche andere Ionen sind ohne Einfluß.Das Verfahren wurde zur Bestimmung von 10–5 bis 10–6% Arsen in folgenden hochreinen Chemikalien eingesetzt: Methanol, Ethanol, Isopropanol, Aceton, Mineralsäuren, Essigsäuren, Ammoniak und Wasserstoffperoxid.
Photometric determination of arsenic in high-purity chemicals
Summary Solutions of silver diethyldithiocarbamidate (Ag-DDTC) in chloroform containing organic bases (brucine) can be used in the photometric determination of very small contents of As after its reduction to AsH3 with metallic zinc.The procedure presented has been characterized with regard to sensivity, precision, detection limit and interferences by other elements.Arsenic can be determined within a range from 0.5 to 5.0 g with a relative standard deviations rel=8.9% for 2.0 g As. The absorptivity is 505=8.5·103l ·mol–1·cm–1, the detection limit according to Kaiser was found to be 0.30 g As. Se(IV), Te(VI), Sb(V) and thiosulphate interfere, many other ions are without effect.The procedure was used to analyse high-purity chemicals (10–5–10–6% As) such as organic solvents, mineral acids, acetic acid, ammonia and hydrogen peroxide.
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10.
Triton X-100, a non-ionic surfactant, has been used to sensitize the reaction of 5-(2-carboxyphenyl)azo-8-quinolinol with uranium in aqueous medium at pH 5.2–6.1 to form a wine red coloured complex. The micellar sensitization results in two and a half-times enhanced molar absorptivity enabling the determination of uranium in rock samples at ppm level, stability of the complex enhanced from 4 hours to at least 72 hours. Extraction of the complex is avoided making the procedure simple, rapid and easy in operation. The molar absorptivity and Sandell's sensitivity of the complex are 1.50·104l·mol–1·cm–1 and 15.9 ng·cm–2, respectively, at max=568 nm. Beer's law is obeyed over the range 0–3.3 g·ml–1 of uranium. An amount as low as 0.19 g·ml–1 of uranium could be determined satisfactorily within a relative standard deviation of ±1.3%. The limits of determination and practical quantitation are 0.29 and 1.80 ppm, respectively. The method was applied to the determination of uranium in soil, stream sediment and rock samples.  相似文献   

11.
Summary A sensitive and selective spectrophotometric method has been developed for the determination of nickel, based on the formation of red ternary complex of nickel with cadion and 1,10-phenanthro- line in alkaline solution (0.5N NaOH). The complex is quantitatively extracted by chloroform and exhibits an absorption maximum at 505 nm. Beer's law is obeyed in the concentration range of 0–2.5g of Ni(II)/5 ml chloroform. The Sandell sensitivity and molar absorptivity of the reaction are 0.000587g cm–2 and 1.0×l05l· mol–1·cm–1, respectively. The method has been applied to the determination of nickel in alloy steels, aluminium alloys and soils.
Extraktion und spektrophotometrische Bestimmung von Nickel mit Cadion und 1,10-Pbenanthrolin als ternärer Komplex
Zusammenfassung Eine empfindliche und selektive Methode zur Bestimmung von Nickel mit Cadion und 1,10-Phenanthrolin wurde ausgearbeitet. Sie beruht auf der Bildung eines roten ternären Komplexes in alkalischer Lösung (0.5N NaOH). Bei 505 nm entspricht die Färbung dem Beerschen Gesetz zwischen 0 und 2,5g Ni(II)/5 ml Chloroform. Der Komplex läßt sich mit Chloroform extrahieren. Die Empfindlichkeit der Reaktion beträgt 0,000587g· cm–2 und die molare Absorption 1.0×105l·mol–1·cm–1. Die Bestimmung von Nickel in Stahl, Aluminiumlegierungen und Böden ergab zufriedenstellende Resultate.
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12.
The cationic copolymerization products of poly (acrylamide-co-trimethylammoniumethylmethacrylate chloride (PTMAC) having cationic monomer percentages of 8%, 25%, and 50% as well as the cationic homopolymer, were characterized with respect to their molecular dimensions. The light-scattering and viscometric measurements were carried out for molecular weights ranging from 200 000 to 12 800 000 g/mol in 1 M NaCl solution at 25°C. It was possible to establish a relationship between the molecular weight and the two parameters: intrinsic viscosity and radius of gyration, for all four polymers.Rheological investigations of the flow properties in 1 M NaCl solution were also carried out using the polymer with a cationic monomer of 50% (PTMAC 50). Structure-property relationships were formulated which made it possible to describe and predict the shear viscosity, both in the zero-shear region (Newtonian region) and in the shear-dependent region (non-Newtonian region) as a function of the polymer concentration, the molecular weight, and shear rate.Abbreviations a exponent of the []-M relationship - A 2 2nd virial coefficient/mol·cm3·g–2 - AAm acrylamide - b slope of the flow-curve in the shear-rate dependent region - c concentration/g·cm–3 - dn/dc refractive index increment/cm3·g–1 - f function - K constant of the []-M relationship/cm3·gt-1 - m c proportion of cationic monomers/mol % - M molecular weight/g·mol–1 - M w weight-average molecular weight/g·mol–1 - M n number-average molecular weight/g·mol–1 - NaCL sodium chloride - PAAm polyacrylamide - PS polystyrene - PTMAC poly(acrylamide-co-trimethylammoniumethylme thacrylate chloride) - RG 20.5 radius of gyration/nm - TMAC trimethylammoniumethylmethacrylate chloride - shear rate/s–1 - critical shear rate/s–1 - viscosity/Pa·s - 0 zero-shear viscosity/Pa·s - s solvent viscosity/Pa·s - sp specific viscosity - [] intrinsic viscosity/cm3·g–1 - relaxation time/s  相似文献   

13.
A simple and sensitive spectrophotometric method is developed for the determination of throium in aqueous medium. The metal ion forms yellow coloured complex with 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone (2,4-DHBINH) in the pH range 2.0–8.0. The complex shows an absorption maximum at 390 nm. The absorbance of the complex is maximum at pH 5.5 Beer's law is obeyed in the range 0.30–7.00 g/ml of thorium(IV). The molar absorptivity and the Sandell's sensitivity of the method are 2.20· 104 l·mol–1·cm–1 and 0.0106 g/cm–2, respectively. The interference of various ions was studied. The composition of the complex is 1:1 {Th(IV) : 2,4-DHBINH}. The first derivative spectrum of the complex shows a zero cross at 391.2 nm and maximum amplitude at 415 nm. Thus a sensitive derivative spectrophotometric method for the determination of Th(IV) is proposed.  相似文献   

14.
A new and simple method for selective spectrophotometric determination of uranium(VI) with 4-(2-pyridylazo)resorcinol (PAR) and N-octylacetamide into benzene over pH 7.0–9.0 is described. The molar absorptivity of the complex with 9 different amides is in the range of (0.40–3.2)·104 1·mol–1·cm–1 at the absorption maximum. Out of these, the most sensitive compound N-octylacetamide (OAA) was chosen for detailed studies in the present investigation. The detection limit of the method is 0.008 g U·ml–1. The system obeys Beer's law in the range of 0–5 g U·ml–1. The method is free from interferences of most of the common metal ions except vanadium(V) and copper(II), which are masked by proper masking agents. The composition of the complex is determined by curve-fitting method. The method has been applied for the recovery of the metal from rock samples and synthetic mixtures.  相似文献   

15.
Summary The colour reaction of magnesium(II) with Khimduchlorophosphonazo-I (KCPA-I) has been studied spectrophotometrically with a view to develop a procedure for the determination of exchangeable magnesium in acidic soils.The optimum acidities are pH 8.78–9.90. The absorption maximum and molar absorptivity of the coloured complex are 580 nm and 1.85 · 104 l · mol–1 · cm–1, respectively. The colour intensity is stable for 4 h and is found to obey Beer's law within the concentration range of 0–20 g per 25 ml. The method is simple and reliable (standard deviation 0.8–1.2%). It has been applied to the determination of exchangeable magnesium.
Neues Reagens für die spektralphotometrische Bestimmung von Magnesium (II): Khimduchlorophosphonazo-I
Zusammenfassung Die Farbreaktion von Magnesium mit Khimduchlorophosphonazo-I wurde im Hinblick auf die Entwicklung eines entsprechenden Analysenverfahrens untersucht. Der optimale pH-Wert liegt im Bereich von 8,78–9,90. Das Absorptionsmaximum liegt bei 580 nm, der molare Extinktionskoeffizient beträgt 1,85 · 104l · mol–1 · cm–1. Die Färbung bleibt 4 h lang stabil und befolgt das Beersche Gesetz von 0 bis 20 g/25 ml. Das Verfahren ist einfach und zuverlässig (Standardabweichung 0,8–1,2%) und wurde zur Bestimmung von austauschbarem Magnesium in sauren Böden angewendet.
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16.
Summary Plutonium(IV) forms a Chlorophosphonazo III complex in 0.5–2M hydrochloric acid. Maximum absorbance occurs at 620 and 685 nm. Beer's law is obeyed over the range of 0–50g per 10 ml and the molar absorptivity is 3.7×104 mol–1 cm–1 at 690 nm. Plutonium can be determined in the presence of fluoride, sulfate and phosphate. However, lanthanides, thorium, uranium and zirconium interfere seriously.
Zusammenfassung Plutonium(IV) bildet in 0,5-bis 2-m Salzsäure mit Chlorphosphonazo III eine Komplexverbindung, deren Absorptionsmaxima bei 630 und 685 nm liegen. Bis 50 g/10 ml entspricht die Farbe dem Beer'schen Gesetz; die molare Extinktion bei 690 nm beträgt 3,7·104l·Mol–1·cm–1. Plutonium kann damit in Gegenwart von F, SO4 2– und PO4 3– bestimmt werden. Lanthanide, Th, U und Zr stören jedoch ernstlich.
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17.
Oxygen/sulfur-bridged incomplete cubane-type molybdenum aqua clusters [Mo3( 3-S)(-X)(-S)2(H2O)9]4+ (X=O, S) in hydrochloric acid react with dien (diethylenetriamine) to give [Mo3( 3-S)(-X)(-S)2(dien)(dien)2]Cl3·nH2O [1, X=O, n=3; 2, X=S, n=4; dien=NH2(CH2)2NH(CH2)2NH], respectively, where each cluster has a deprotonated dien. The X-ray structural analysis of 1 revealed proton dissociation from an amino group of one of the three dien ligands: one Mo–N distance [1.987(4) Å] is clearly shorter than the other eight Mo–N distances [2.229(3)–2.276(3) Å]. The 1H NMR spectra of the Mo–dien clusters 1 and 2 in D2O show two well-resolved methylene proton signals in the 2.8- to 3.0-ppm region, which indicates that both deprotonated amines in 1 and 2 receive D+ ions from solvent D2O. The factors for the proton dissociation are discussed.  相似文献   

18.
Guiacol, i.e. o-hydroxyanisole, gives a distinct color reaction with U(VI) suitable for spectrophotometric determination of the metal. The complex formed in the reaction has an absorption maximum at 352 nm. Optimum pH for the color development ranges from 6.5 to 8.5. The molar absorptivity and Sandell's sensitivity of the method were found to be 3.75×103 l·mol–1·cm–1 and 0.063 g·cm–2, respectively. Many anions and cations do not interfere up to 100 ppm. The method has been made very specific by selective extraction of U(VI) with TBP from a mixture of different cations and anions in the presence of 60% NH4NO3 as salting out agent followed by developing the color in the non-aqueous phase by adding quaiacol in methanol at pH 6.5 to 8.5 An amount as low as 30 g of uranium (VI) per 10 ml of the solution could be satisfactorily determined with an RSD of ±2.0%. The method was applied to rock samples after U(VI) had been extracted from a sample solution into 25% TBP in hexane. Results obtained by the new method compare very well with those of conventional fluorimetric and radiometric assays. The features of the method include excellent precision, rapidity, good selectivity, and ease of performance.  相似文献   

19.
The spectra and kinetics of short-lived intermediates formed from aqueous (0.1 N NaOH) solutions of the natural mixture of humic and fulvic acids (HFA) were studied by laser flash photolysis using excitation wavelengths of 337, 390, 470, and 520 nm. Laser photolysis of HFA with light of 520 and 470 nm results in the formation of triplet excited states (THFA) characterized by the broad absorption spectrum with a maximum near 630 nm and lifetimes of 0.15 ms in deoxygenated solutions. The formation of two types of THFA with lifetimes of 0.1 and 2 ms and absorption spectra with maxima at 570 nm is observed under photolysis with light of 337 and 390 nm. The estimation of quantum yields of THFA gives 1 and 0.3% under photolysis with excitation wavelengths of 337 and 520 nm, respectively. The rate constants of THFA quenching by molecular oxygen are equal to (7—8)·108 L mol–1 s–1.  相似文献   

20.
Prussian blue and its analogs bonded to poly(vinylamine hydrochloride) (PVAm · HCl) containing FeII or FeIII and M2+ (M=Fe, Co, Cu) in a 11 molar ratio were obtained by the reaction of [Fe(CN)6] n (n=3,4) with M2+ ion-PVAm · HCl mixture in aqueous solution. Under a limited polymer concentration (TVAm/TFe over 10), these polymer complexes thus obtained were stable and soluble in water. By casting these solutions, colored films can be produced. The formation of Prussian blue and its analogs bonded to PVAm · HCl was also investigated by the Benesi-Hildebrand method. The molar extinction coefficients of intervalence charge transfer (FeIIFeIII, CoIIFeIII, FeIICuII) band for MFe(CN)6](n–2)– bound to PVAm · HCl (M=Fe, Co, Cu) were found to be 10,100–9601 · mol–1 · cm–1 at 25 C. The formation constants were found to be in the range of 107 to 1010 M–1. The changes of enthalpy (H) and entropy (S) were found to be in the range of –10.4 to –22.5 kJ · mol–1 and 5.7 to 52.9 J · K–1 mol–1 respectively, at 25C.  相似文献   

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