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A new method is proposed for collecting traces of nickel from aqueous solution by precipitation as the alpha-furildioxime complex and adsorption of this onto microcrystalline naphthalene. The precipitate is collected, dried, and dissolved in chloroform, and the nickel is determined spectrophotometrically at 438 nm. The linear calibration range is 2-35 mug/10 ml. The molar absorptivity is 1.6 x 10(4) l. mole(-1). cm(-1). The main advantage is that the nickel is collected quantitatively after only a few seconds'shaking. The effect of varying pH, amount of reagent, naphthalene or buffer, shaking and standing time, and interferences have been investigated.
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PMID:Spectrophotometric determination of nickel after separation by adsorption of its alpha-furildioxime complex on naphthalene. 1896 60

The chelate is quantitatively formed only in the pH range 6.5-7.5. Despite the large stability constant, a large excess of reagent is required to suppress interferences. The most suitable wavelength for the photometric measurement is 500 nm, where the molar absorptivity is 1.607 x 10(4) 1.mole(-1). cm(-1). The procedure given allows determination of 8 x 10(-4)% Co in a l-g sample. The standard deviation for cobalt is 2.1 mug/100 ml (f = 19). Applications to analysis of iron and steel, nickel, copper, ores and silicates are given.
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PMID:Photometric determination of cobalt with nitroso-R-salt. 1896 9

A procedure is described for the extractive spectrophotometric determination of nickel and palladium with quinoline-2-aldehyde thiosemicarbazone. At pH 7.5 nickel forms a 1:2 complex which is soluble in chloroform and has an absorption maximum at 460 nm. Palladium forms a 1:2 complex with maximum absorbance at 510 nm which can be extracted into MIBK from 1M HCl. Both complexes are stable and conform to Beer's law. The molar absorptivities for nickel and palladium are 1.58 x 10(4) and 2.6 x 10(3) 1.mole(-1). cm(-1) respectively. The proposed method is suitable for detection and determination of nickel and palladium in the presence of associated metal ions. The results of the analysis of synthetic mixtures and standard samples are reported.
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PMID:Quinoline-2-aldehyde thiosemicarbazone (QAT) as spectrophotometric reagent for palladium and nickel. 1896 96

A simple, selective and highly sensitive procedure for spectrophotometric determination of nickel has been developed. At pH 5.5, nickel reacts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in water-ethanol medium to form a red-violet complex which has two absorption maxima, at 520 and 56Onm. The molar absorptivity at 56Onm is 1.26 x 10(5) l.mole(-1).cm(-1). Beer's law is obeyed for 0-15 mug of nickel. Nickel in aluminium alloys and electroplating waste-water has been determined by this method.
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PMID:Sensitive spectrophotometric determination of nickel(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol. 1896 90

The conditions for the formation of a suitable coloured palladium ion-association complex with a basic dye have been examined, and a spectrophotometric method developed for the determination of palladium with bromide and Rhodamine 6G (R6G). Benzene is used for flotation and dimethylformamide for dissolution of the ion-association complex. The molar absorptivity is 3.0 x 10(5) l. mole(-1).cm(-1) at 53Onm. Beer's law is obeyed up to a palladium concentration of 0.3 mug/ml. The composition of the complex is [R6G(+)](3)[PdBr(3-)(5)]. Platinum interferes severely but other platinum metals interfere to a lesser degree. The method has been applied to the determination of traces of palladium in metallic platinum after a preliminary separation with nickel dimethylglyoximate as collector.
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PMID:Flotation-spectrophotometric method for determining palladium by means of the ion-association complex of pentabromopalladate(II) with Rhodamine 6G. 1896 58

Bromopyrogallol Red (BPR) combines with iron(III) in the presence of hexadecyltrimethylammonium bromide (CTMAB) to form an intensely blue complex having a molar absorptivity of 5.20 x 10(4)l. mole(-1).cm(-1) at 635 nm. The complex contains three molecules of BPR co-ordinated to an iron(III) ion, and two molecules of CTMAB associated with each BPR molecule, giving the overall formula (CTMAB)(6)(BPR)(3)Fe(III). Iron(II) also reacts with BPR and CTMAB in the presence of dissolved oxygen to form the iron(III) complex. No oxidizing or reducing agents are required for the determination of total iron in mixtures of iron(III) and iron(II), and Beer's law is followed from 0.05 to 0.5 ppm iron (1.00-cm cells). Of nine metal ions tested at the 1-ppm level, only manganese(II) and vanadium(V) interfere. Copper(II), cobalt(II), zinc, lead, nickel, aluminium and chromium(III) produce little or no interference when present at 100 ppm concentration.
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PMID:Spectrophotometric study on the reactions of iron(II) and iron(III) with Bromopyrogallol Red and hexadecyltrimethylammonium bromide. 1896 46

The importance of selecting the most suitable counter-cation in the solvent extraction-spectrophotometric determination of an anionic metal chelate containing a sulphonic acid group is demonstrated and discussed. In the case of cobalt and 2-nitroso-1-naphthol-4-sulphonic acid (nitroso-NW acid), the most suitable counter-cation is the tetrabutylammonium ion (Bu(4)N(+)): in this case only the ion-pair of the anionic cobalt chelate is extracted into chloroform and the excess of the nitroso-NW acid remains in the aqueous phase. The absorption maximum of the chelate in chloroform is at 307nm, at which the molar absorptivity is 6.5 x 10(4)l.mole(-1).cm(-1). The absorbance of the reagent blank at 307 nm is less than 0.010. By use of nitroso-NW acid and Bu(4)N(+), trace amounts of cobalt may be determined in nickel salts and in iron and steel samples.
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PMID:Selection of the counter-cation in the solvent extraction of anionic chelates: Spectrophotometric determination of trace amounts of cobalt with 2-nitroso-1-naphthol-4-sulphonic acid and tetrabutylammonium ion. 1896 89

Twenty-two new hydrazones were synthesized for evaluation as possible calorimetric reagents for trace determinations of iron, cobalt, nickel, copper and zinc. Spectrophotometric studies revealed that several show promise as sensitive reagents, with possible utility for simultaneous determinations of two or more of the metals. Conclusions regarding geometric structures of some of the hydrazones and chelates were deduced from mole-ratio studies.
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PMID:Synthesis and metallochromic properties of some hydrazones of 2-, 3- and 8-hydrazinoquinoline. 1896 38

The reaction between cadmium and 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol (5-Cl DMPAP) in aqueous alcohol media at pH 8.8-10.7 results in an intense violet colour which is stable for at least 8 hr. The composition is 2:1 reagent:metal and the formation constant (5.29 +/- 0.01) x 10(18). Beer's law is obeyed up to 1.34 ppm of cadmium at 550 nm. The optimal concentration range (Ringbom) is between 0.16 and 0.72 ppm. The apparent molar absorptivity at 550 nm is (1.20 +/- 0.01) x 10(5) l.mole(-1). cm(-1), making the sensitivity one of the highest known. The interference due to copper(III), iron(III), cobalt(II), nickel(II), gold(III), zinc(II) and manganese(II) can be suppressed.
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PMID:Spectrophotometr1c determination of cadmium with 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol. 1896 6

A sensitive method for the spectrophotometric determination of indium with 1-(2-pyridylmethylideneamine)-3-(salicylideneamine)thiourea is proposed. A yellow complex is formed at pH 4.5 (succinate buffer) in a medium containing 40% dimethylformamide, and the absorbance is measured at 415 nm. The molar absorptivity is 6.2 x 10(4)l.mole(-1).cm(-1). The relative standard deviation of the procedure is 1.5%. The method has been applied to determination of indium in a nickel alloy and three zinc ores, with prior isolation of indium by co-precipitation with ammonia and extraction into n-butyl acetate from 5M hydrobromic acid.
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PMID:Spectrophotometric determination of indium in nickel alloys and zinc ores with 1-(2-pyridylmethylideneamine)-3-(salicylideneamine)thiourea. 1896 49


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