Spectrophotometic Determination Of Tin In Steels With2-(5-Nltro-2-Pyridylazo)-5-[N-n-Propyl-N-(3-Sulfopropyl)Amino]phenol

ABSTRACT

A highly sensitive azo dye, 2-(5-nitro-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol (Nitro-PAPS), is used as a colorimetric reagent for the determination of tin(IV) content. Nitro-PAPS reacts with tin(IV) to form a water-soluble complex in 1.0 M acetic acid. Full color development is attained within 5 minutes, and maintains constant absorbance for at least 24 hours. The apparent molar absorptivity is 7.7 x 10⁴ dm³ mol^?1 cm^?1 at a maximum wavelength of 580 ran. Beer's law is obeyed for tin(IV) in the range of 0-1.2 μg ml^?1. The proposed method is successfully applied to the determination of trace amounts of tin in steels.     

Selective Spectrophotometric Determination of Palladium (II) With 2-(5-Bromo-2-Pyridylazo)-5-(Diethylamino)-Phenol

Abstract

A spectrophotometric study of the Pd(II) complex of a reagent 2-(5-Bromo-2-Pyridylazo)-5-(diethylamino)-Phenol (5-Br-PADAP) is presented. A violet complex is formed at pH 3.53, and shows maximal absorbance at 585 nm with molar absorptivity of 3.86 × 10⁴ 1. mol^?1 cm^?1. Beer's law is obeyed up to 50 μ of Pd(II). The method offers the advantages of simplicity, high precision, requires no extraction and is very selective, where 5.0 mg Pt(VI) and 0.3 mg Au(III) ions do not interfere.     

Direct and Second Order Analogue Derivative Extraction-Spectrophotometric Determination of Iron with 2 (4, 5-Dimethyl-2-Thiazolylazo)-4, 6-Dimethylphenol

Abstract

An extraction-spectrophotometric method for the determination of trace amounts of iron based on its extraction into chloroform with 2-(4, 5-dimethyl-2-thiazolylazo)-4, 6-dimethylphenol has been developed, which allows the determination of 5–28 μg Fe (?₇₇₃ = 1.38×10⁴ 1. mol^?1. cm^?1). The use of second order analogue derivative spectrophotometry allows the determination of down to 0.2–5 μg, Fe. The methods are quite selective and have been applied to the determination of iron in mineral waters.     

Complexing Properties of Uranium and Lanthanoids With 4-(2-Thiazolylazo)-6-Chlororesorcinol

Abstract

4-(2-Thiazolylazo)-6-chlororesorcinol (TAR-Cl) reacts sensitively with uranyl(II) and lanthanoids(III), and forms reddish-brown 1:1 and 1:2 complexes. The complexing behaviors were examined spectrophotometrically. The absorption maxima of the complexes are focused near 553 nm and the optimum pH for complexation lies between 6.5–8.8. Beer's law holds up to about 2 × 10^?5 mol 1^?1, with a molar absorptivity of 3.00 × 10⁴ 1 mol^?1 cm^?1 for uranium and 6 × 10⁴ 1 mol^?1 cm^?1 level for each lanthanoid. The absorptivities are increased with the atomic number, especially in light lanthanoids, that are correlative both to the lanthanoid contraction and the basicity of ortho hydroxyl group in the resorcinol ring, but such effects are not clearly recognized in heavy lanthanoids. Effect of masking agents was also examined, and uranium could be determined selectively in the presence of lanthanoid mixtures by the addition of CyDTA.     

2-(2-Thiazolylazo)-p-cresol(TAC) as a Reagent for the Spectrophotometric Determination of Lead(II)

Abstract

The reaction between lead(II) and 2-(2-Thiazolylazo)-p-Cresol(TAC) in the presence of TERGITOL NPX (4 mg/ml) at an apparent pH 9.0–10.0 results in an intensely colored complex which is stable for at least 4 hr.

The composition of the complex is 1:2 cation: TAC and the log of the formation constant is 11.92 ± 0. 40. Beer's law is obeyed up to 6.0μg.ml^?1 of lead(II) at 650nm.

The apparent molar absorptivity at 650 nm is 2.07 × 10⁴ 1. mole^?1.cm^?1 and the detection limit was obtained as 10.0 ng.ml^?1 of lead(II).

The method is applied to determination of lead(II) in copper-base alloy.     

Ternary Complex Nickel(II)/3-(4′,5′-Dimethyl-2′-Thiazolylazo)-2,6-Dihydroxybenzoic Acid/Cyanide. Spectrophotometric Determination of Nickel

Abstract

A spectrophotometric method for nickel has been developed based on the formation of a ternary complex in the system Ni(II)/3-(4′,5′-dimethyl-2′-thiazolylazo)-2,6-dihydroxybenzoic acid/cyanide at pH 9.2 (borate buffer), which allows the determination of 0.05–0.47ppm of nickel (ε = 3.53×10⁴ 1.mol^?1. cm^?1) at 538nm. Interferences have been studied and the method applied to the determination of nickel in low alloy steels.     

Use of clinoptilolite loaded with 1-(2-pyridylazo)-2-naphthol as a sorbent for preconcentration of Pb(II), Ni(II), Cd(II) and Cu(II) prior to their determination by flame atomic absorption spectroscopy

A solid phase extraction system for separation and preconcentration of trace amounts of Pb(II), Ni(II), Cd(II) and Cu(II) is proposed. The procedure is based on the adsorption of Pb²⁺, Ni²⁺, Cd²⁺ and Cu²⁺ ions on a column of 1-(2-pyridylazo)-2-naphthol (PAN) immobilised on surfactant-coated clinoptilolite prior to their determinations by Flame Atomic Absorption Spectroscopy (FAAS). The effective parameters including pH, sample volume, sample flow rate and eluent flow rate were also studied. The analytes collected on the column were eluted with 5 mL of 1 mol L^?1 nitric acid. A concentration factor of 180 can be achieved by passing 900 mL of sample through the column. The detection limits (3 s) for Cd, Cu, Pb and Ni were found to be 0.28, 0.12, 0.44 and 0.46 µg L^?1, respectively. The relative SDs at 10 µg L^?1 (n = 10) for analytes were in the range of 1.2–1.4%. The method was applied to the determination of Pb, Ni, Cd and Cu in water samples.     

2-(5-取代苯氧甲基-1,3,4-噻二唑-2-亚胺基)-5-(取代苯基亚甲基)-4- 噻唑啉酮的合成

以2-氨基-5-取代苯氧甲基-1,3,4-噻二唑(1)为起始原料, 合成了中间体2-氯乙酰氨基-5-取代苯氧甲基-1,3,4-噻二唑)-2-乙酰亚胺(2)和2-(5-取代苯氧甲基-1,3,4-噻二唑-2-亚胺基)-4-噻唑啉酮(3), 化合物3进一步与取代苯甲醛发生类Knoevenagle缩合反应, 得到了一系列2-(5-取代苯氧甲基-1,3,4-噻二唑-2-亚胺基)-5-(取代苯基亚甲基)-4-噻唑啉酮类化合物4a～4p. 目标化合物4a～4p的结构经IR, ¹H NMR和元素分析确证.     

Ultrasonic-assisted supramolecular solvent-based liquid phase microextraction of mercury as 1-(2-pyridylazo)-2-naphthol complexes from water samples

A separation-preconcentration method based on supramolecular solvent ultrasonic-assisted liquid-phase microextraction (Ss-USA-LPME) for spectrophotometric determination of mercury as 1-(2-pyridylazo)-2-naphthol (PAN) chelates has been established. Red coloured Hg(II)-PAN hydrophobic complex was extracted into the supramolecular phase (1-decanol/THF) at pH 9.5. The extract was separated from aqueous phase by centrifugation, diluted with ethanol and determined by UV–Vis spectrophotometer at λ_max = 560 nm. The influences of important analytical parameters such as pH, amount of PAN, 1-decanol and THF, sample volume and matrix effects for the quantitative recoveries were examined and optimised. Under the optimised experimental conditions, the amount of ligand, 1-decanol and THF were 1.0 × 10^–4 M, 200 µL and 300 µL, respectively. The optimum time of ultrasonic bath and centrifugation were found as 2 min and 5 min. A linear calibration graph was obtained linearly in the concentration ranges of 8.3–1000 µg L^?1. The preconcentration factor was obtained as 20. The limit of detection (LOD) was 2.6 µg L^?1 with the relative standard deviation (RSD) of 2.4% for mercury (C = 100 µg L^?1, n = 7). The validity of the developed Ss-USA-LPME technique was checked with a certified reference material of NIST 1641d. The presented method has been successfully applied to the determination of mercury in water samples.     

Simultaneous First-Derivative Spectrophotometric Determination of Nickel and Manganese Complexes with 2-(2-Pyridylmethyleneamino)phenol

Abstract

A method is proposed for the simultaneous determination of nickel and manganese by first-derivative spectrophotometry based on their reactions with 2-(2-pyridylmethyleneamino)phenol (PMAP) Schiff base. The method allows the determination of Ni and Mn in the concentration range 0.3–3.0 μg ml^?1 in mixtures with their ten-fold concentration ratio. The method has been applied for Ni and Mn determination in bronzes. To optimize the experimental conditions for spectrophotometric determination of Mn with PMAP stability constants at different pH values have been determined. A critical evaluation of the proposed method was performed by statistical analysis of the experimental data.     

Adsorptive Preconcentration for Voltammetric Measurements of Trace Level of Iron (III) With 2- (2- Thiazolylazo)-4-Methylphenol

Abstract

This paper describes an electrochemical stripping procedure for ultratrace measurements of iron, in which preconcentration is achieved by the adsorption of a iron-[2-thiazolylazo)-4- methyl phenol] complex onto a static mercury drop electrode Cyclic voltammetry was used to characterize the interfaciai and redox behavior. For a 5 minute preconcentration time, the detection limit found was 1.8 × 10^?0mol/1. Optimum experimental conditions were found by the use of a stirred triethanolamine (pH 8.6) solution with 2-[2-thiazolylazo- 4- methyl phenol] concentration of 1.0 × 10^?5 mol/1, a preconcentration potential of ?0.46V and linear scan mode. With preconcentration for 30 sec., calibration plots for iron are linear for the 5–29 μ g/1 range. Possible interferences by masking agents and several trace ions have been investigated. The interference of copper and uranium are eliminated by addition of CyDTA and carbonate ion respectively. Simultaneous determination of iron with copper and nickel is possible. The merits of the aforementioned procedure are demonstrated in the analysis of fresh water.     

2-[2-(5-Bromopyridyl)azo]-5-dimethylaminophenol; a new sensitive reagent for cadmium

Cadmium(II) reacts with 2-[2-(5-bromopyridyl)azo]-5-dimethyl-aminophenol (5-Br-DMPAP) in aqueous solution; the complex can be extracted with organic solvents such as chloroform, 3-methyl-l-butanol and methyl isobutyl ketone at pH 8–10.5 to give a red solution which absorbs at 525–555 nm. The absorbance in organic solvents is stable and the system conforms to Beer's law; the optimal range in 3-methyl-1-butanol for measurement in 1.00-cm cells is 0.01–l p.p.m. cadmium. Moderate amounts of many cations and anions do not interfere, and interfering cations such as zinc, copper, manganese and nickel can be separated by extraction with dithizone. The 5-Br-DMPAP method is one of the most sensitive procedures available for the determination of cadmium; the molar absorptivity in a 3-methyl-1-butanol extract is 1.41·10⁵ 1 mol^?1 cm^?1 at 555 nm.     

Spectrophotometric Determination of Manganese with 4(5)-Imidazolealdoxime (Imalox)

Abstract

A method is described for the spectrophotometric determination of manganese by means of its complex with 4(5)-imidazolealdoxime, IMALOX, formed in alkaline medium. The colour system has its absorption maximum at 350 nm and obeys Beer's law over the range 0.8–8.0 μg of Mn per ml. The optimum range is 1–5 μg m^?1. The molar absorptivity is 7850 1 mol^?1 cm^?1. Relatively few ions interfere, and these can be masked with cyanide, tartrate and NTA. The experimental results have been critically analyzed and a comparison with the main spectrophotometric reagents for manganese is presented.     

Three Cu(II) (R)-2-chloromandelato complexes generated from dipyridyl-type ligands with different spacer lengths: syntheses,crystal structures,and ferroelectric properties

Three Cu(II) complexes, Cu₂(bpy)(H₂O)(Clma)₂ (1), Cu₂(bpe)(H₂O)₂(Clma)₂ (2), and Cu(bpp)(Clma) (3), were synthesized (HClma = (R)-2-Chloromandelic acid, bpy?=?4,4′-dipyridine, bpe?=?1,2-di(4-pyridyl)ethylene, bpp?=?1,3-di(4-pyridyl)propane). Complexes 1, 2, and 3 are constructed from 1-D coordination arrays generated from Cu₂(H₂O)(Clma)₂, Cu₂(H₂O)₂(Clma)₂, and Cu₂(Clma)₂ moieties and linked through bpy, bpe, and bpp co-ligands, respectively. 1 and 2 are assembled into 3-D supramolecular networks via O–H?O hydrogen bonds with topology of (6³)(6⁹·8) and (4¹²·6³), respectively, and 3 is assembled into a 3-D architecture through C–H?O hydrogen bonds with topology of (4³·6³)(4³)(4⁴·6⁵·8)(4⁶·6⁶·8³). Compounds 1, 2, and 3 crystallized in acentric space groups P2₁, P1, and P2₁, which exhibit significant ferroelectricity (remnant polarization Pr?=?0.008?μC?cm^?2, coercive field Ec?=?21.4?kV?cm^?1, the spontaneous saturation polarization Ps?=?0.167?μC?cm^?2 for 1, Pr?=?0.183?μC?cm^?2, Ec?=?1.69?kV?cm^?1, and Ps?=?0.021 μC?cm^?2 for 3). Results from infrared and thermal analyses are also discussed.     

Extraction-spectrophotometric determination of trace iron (II) in sea water with 2-[2-(3,5-dibromopyridyl)azo]-5-diethylaminobenzoic acid

An extraction-spectrophotometric method is described for the determination of traces of iron(II) with 2-[2-(3,5-dibromopyridyl)azo]-5-diethyl-aminobenzoic acid. The reagent forms a stable and blue 12 iron/reagent complex that can be extracted into chloroform. The apparent molar absorptivity of the iron(II) complex is 1.09 × 10⁵ 1 mol^–1 cm^–1 at 624 nm in chloroform. The reagent is relatively selective; interferences from cobalt, copper, nickel and vanadium can be removed by using dimethylglyoxime and EDTA. The method is applied to the determination of iron (II) in sea water and aluminium alloys with good precision and accuracy.     

2-[2-(6-Methylbenzothiazolyl)azo]-5-Diethylaminobenzoic acid as a new analytical reagent for the spectrophotometric determination of nickel

A new thiazolylazo chromogenic reagent, 2-[2-(6-methylbenzo-thiazoly)azo]-5-diethylaminobenzoic acid (6-Me-BTAEB), has been synthesized. Its chromogenic reaction with microamounts of nickel in the presence of sodium dodecylsulfate (SDS) has been thoroughly studied. 6-Me-BTAEB reacts with nickel(II) in weak acid medium containing appropriate amounts of SDS to form a blue-violet complex with high sensitivity, good selectivity and high stability. The composition is found to be 1:2 (nickel to 6-Me-BTAEB) and its absorption maximum is at 650 nm with an apparent molar absorptivity of 1.67 × 10⁵l mole^–1 cm^–1. Beer's law is obeyed over the range 0-0.4 g of nickel per ml. The proposed method has been applied to the direct determination of nickel in aluminium alloys, pure magnesium and low alloy steels at the 0.2–0.3% (w:w) level with satisfactory results.     

Synthese Originale de 5-Aryl (ou 5-benzyl)-2[(1-Diethoxyphosphonyl)methyl]-1,3,4-oxadiazoles par Action du Phosphonomethylhydrazide sur les Imidates N-Acyles

The phosphonomethylhydrazide 2a reacts with N-acylated imidates 3a–d to give the corresponding 5-aryl (or 5-benzyl)-2-[(1-diethoxyphosphonyl)methyl]-1,3,4-oxadiazoles 4a–d after the elimination of ethanamide 5. Compounds 2a–e are prepared by the action of triethyl phosphonoacetate 1 with hydrazine and its derivatives. The structures of 1,3,4-oxadiazoles 4a–d and hydrazides 2a–e have been unequivocally confirmed by means of IR, ¹ H, ¹³ C, ³¹ P NMR and mass spectrometry.     

5-(2′-Carboxyphnyl) Azo-8-quinolinol as a Sensitive Reagent for Extractive Spectrophotometric Determination of Nickel

Abstract

A new sensitive extractive spectrophotometric method for the determination of nickel in sub-microgram level is discussed. 5-(2′-carboxyphenyl) azo-8-quinolinol reats with nickel at pH 5.2 to 6.1 to produce a wine red complex extractable in isomayl alcohol. The complex is stable for 24 hrs. Beer's law is obeyed in the range 0.04 to 0.60 ug of nickel per ml. The molar absorptivity and Sandell's sensitivity of the method are 5.5 × 10⁴1. mol^?1 cm^?1 and 0.001 μg cm^?2, respectively, at wavelength of maximum absorption (λ max 540 nm). Effects of diverse ions and variables have been studied in detail. The method has been applied to the determination of nickel in alloys like manganin, constantan, german silver, bronze, steel and in geological samples. Features of the method include high sensitivity, excelllent reproducibility and reliability.     

Polarographic Determination of Palladium(II) in Rocks After Extraction with [5-(4-Dimethylaminebenzylidene)rhodanine] and Methyl Isobutyl Ketone

Abstract

A sensitive and selective method for the determination of palladium(II) in mineral veins of quartz, a pegmatite rock from Campo Largo County, Parana State, Brazil, was investigated. After liquid-liquid extraction of Pd^2- from aqueous solution, pH 2.4, with [5-(4-dimethylaminebenzylidene)rhodanine] and methyl isobutyl ketone, the back-extraction was performed with 3.0 mol.L^?1 sulfuric acid. At pH 2.4, only trace amounts of gold(III) and silver(I) were co-extracted with palladium(II). However, neither Au³⁺ nor Ag⁺ interfere with palladium(II) determination by differential pulse polarography using tris(hydroxymethyl)aminomethane and potassium nitrate, pH 11.0, as supporting electrolyte. The observed detection limit was 1.0 μg(Pd²⁺).L^?1.     

Synthesis,structure, spectroscopic,and DNA binding properties of Co(III) and Ni(II) complexes with ((E)-2-(amino((pyridin-2-ylmethylene)amino)methylene)maleonitrile)

Two new complexes, [Co(L)₂]Cl·(MeOH)₂ (1) and [Ni(L)₂]₄·EtOH (2) (L?=?(E)-2-(amino((pyridin-2-ylmethylene)amino)methylene)maleonitrile), were synthesized and characterized by X-ray crystallography, IR, UV, and fluorescence spectroscopy. According to X-ray crystallographic studies, each metal was six-coordinate with six nitrogens from two ligands. Both complexes form two-dimensional supramolecular networks via hydrogen bonding and π–π interactions. Ultraviolet and visible spectra showed that absorptions arise from π–π ^?, MLCT, and d–d electron transitions. Fluorescence spectroscopy revealed moderate intercalative binding of these two complexes with EB–DNA, with apparent binding constant (K _app) values of 9.14?×?10⁵ and 3.20?×?10^5?M^?1 for Co(III) and Ni(II) complexes, respectively. UV–visible absorption spectra showed that the absorption of DNA at 260?nm was quenched for 2 but quenched then improved for 1 with addition of complexes, tentatively attributed to the effect of the combined intercalative binding and electrostatic interaction for 1.