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Utilizing similar methods and ideas of QSAR in metal toxicity assessment, we tried to establish the relationship between the ion characteristics of heavy metals and the biosorption capacity by waste biomass of Saccharomyces cerevisiae, obtained from a local brewery. The biosorption experiment was carried out and the maximum biosorption capacity (q(max)) was determined by the Langmuir isotherm model. The values of q(max) decreased in order on mole basis: Pb2+ > Ag+ > Cr3+ > Cu2+ > Zn2+ > Cd2+ > Co2+ > Sr2+ > Ni2+ > Cs+. The biomass prefer to bind class B ions (Pb2+ and Ag+), then borderline ions, and last hard ions (Sr2+ and Cs+) based on the HASB principle. Twenty two parameters of physiochemical characteristics of ions were selected to correlate q(max). Linear regression analysis showed that only one parameter, i.e., the covalent index X2(m)r was correlated well to q(max) for all metal ions tested. The greater the covalent index value of metal ion was, the greater was potential to form covalent bonds with biological ligands, and the larger was the metal ion biosorption. Classification of metal ions (for divalent ion or for soft-hard ion) improved the models. More properties such as polarizing power Z2/r or the first hydrolysis constant /lgK(OH)/ or ionization potential IP were statistically significant. X2(m)r seemed to be suitable to account for metal ions containing soft ions, whereas Z2/r, /lgK(OH)/ and IP suitable for only soft ions or metal ions without soft ions.
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PMID:[Relationship of biosorption capacity of heavy metal ions by Saccharomyces cerevisiae and their ionic characteristics]. 1792 2

In this paper we have investigated nonenzimatic hydrolysis of ATP stimulated by calixarene C-107. It has been shown the dependences of the kinetic characteristics from reagent concentration: the maximal value released Pi did not depend on ATP concentration and linearly increased with the growth of calixarene concentration. Besides the growth concentration of ATP or calixarene increased the maximum instantaneous velocity of the reaction and decreased characteristic time. It was identified that univalent cation of Na+, K+, Li+, choline+ and bivalent cation of Ca2+ or Mg2+ did not influence the reaction of ATP hydrolysis, in the presence of other bivalent cation the inhibition of the reaction occurred in line with the sequence: Cu2+ > Ba2+ > Pb2+ > Sr2+ > Ni2+ = Zn2+ > Mn2+ > > Co2+. The alkalization in the range of pH 6.0-8.0 stimulated the ATP hydrolysis. The magnitude of activation energy of the reaction was 50.7 +/- 8.9 kilojoules per mole. The specificity for nucleoside tri- and di-phosphates was not observed. Obtained data can be useful for designing the synthetic ATP-hydrolyzing catalysts and also for subsequent investigation of kinetics, energetics and mechanism of both enzymatic and nonenzymatic ATP hydrolysis reaction.
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PMID:[Calixarene-dependent hydrolysis of ATP. II. The catalytic properties of reaction stimulated by calixarene C-107]. 1895 28

A spectrophotometric method based on the extraction of cobalt with benzene solutions of oximidobenzotetronic acid (OBTA) is proposed for the estimation of 0.2-3.0 ppm of cobalt. The 3:1 OBTA : Co complex containing cobalt(III) has its absorption maximum at 430 nm; its molar absorptivity in benzene is 1.82 x 10(3)L. mole(-1). mm(-1). Since the blue iron(II) complex is not extracted into benzene, iron(II) and cobalt(II) can be separated and determined spectrophotometrically.
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PMID:Rapid spectrophotometric determination of cobalt after extraction using oximidobenzotetronic acid. 1896 Jun 49

Cobalt(II) and 3-[(5-chloro-2-pyridyl)azo]-2,6-diaminopyridine (5-Cl-PADAPy) in slightly acid, neutral or alkaline media form a blue complex which is very stable even in the presence of mineral acids. The complex has two absorption maxima, at 575 and 620 nm. in 1.2M hydrochlororic acid. The system conforms to Beer's law; the optimal range for a 1-cm cell is 0.2-1.2 ppm cobalt. Milligram amounts of common anions and cations do not interfere. The molar absorptivity is 3.69 x 10(4) 1.mole(-1).cm(-1) at 620 nm.
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PMID:o-Amino heterocyclic azo-dyes as analytical reagents-II Spectrophotometric determination of cobalt with 3-[(5-chloro-2-pyridyl)azo]-2,6-diaminopyridine. 1896 1

A simple and highly selective spectrophotometric method for the determination of cobalt based upon the rapid reaction with PAN in the presence of surfactants and minute amounts of ammonium persulphate at pH 5.0 is described. The cobalt(III) chelate is made water-soluble by a neutral surfactant. Triton X-100, combined with sodium dodecylbenzene sulphonate (DBS). Iron(III), bismuth, tin(IV) and aluminium are masked with oxalate or citrate. Iron(II) must be absent. The other metal-PAN chelates, except that of nickel, are readily decomposed by EDTA. Up to 150 microg of nickel does not interfere. When larger amounts up to 625 microg are present, the absorbance can be corrected by measurements at two wavelengths. In a strongly acid medium (below pH 0.5) the nickel and other metal chelates are completely and instantaneously decomposed, while the cobalt(III) chelate remains unchanged. When, in place of EDTA, several ml of 6M hydrochloric acid are added after the colour development, nickel in quantities up to 1250 microg can be tolerated. A several hundredfold excess of zinc and manganese does not interfere. At 620 nm Beer's law is obeyed over the cobalt concentration range 0.4-3.2 microg/ml. The precision (95% confidence) is +/- 1.0 microg for 100 microg of cobalt. The molar absorptivity is 1.90 x 10(4) l. mole(-1) .cm(-1).
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PMID:Spectrophotometric determination of cobalt with 1-(2-pyridylazo)-2-naphthol and surfactants. 1896 58

2-Nitroso-5-diethylaminophenol (nitroso-DEAP) is a useful reagent for cobalt, with which it forms a 1:3 complex. Its pK(a1) and pK(a2) values are 2.83 and 8.38, and the formation constant, log K(MR(3)), is 24.73. The reagent and complex may be extracted into 1,2-dichloroethane from water, the log of the respective partition coefficients being 2.35 and 7.3. The extracted cobalt complex is not stripped by 6M hydrochloric acid, whereas excess of the reagent is. The molar absorptivity of the complex in 1,2-dichloroethane is 6.2 x 10(4) 1.mole(-1) cm(-1) at 462 nm, which is larger than that of other nitroso derivatives.
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PMID:Reaction of cobalt with 2-Nitroso-5-Diethylaminophenol and the solvent extraction of its cobalt complex. 1896 12

A method for determining up to about 6% of tungsten in ores and mill products is described. It is based on the extraction of the yellow tungsten(V)-thiocyanate-diantipyrylmethane ion-association complex into chloroform from a 2.4M sulphuric acid-7.8M hydrochloric acid medium containing ammonium hydrogen fluoride as masking agent for niobium. The molar absorptivity of the complex is 1510 1. mole(-1).mm(-1) at 404 nm, the wavelength of maximum absorption. Moderate amounts of molybdenum and selenium may be present in the sample solution without causing appreciable error in the result. Interference from large amounts is avoided by separating these elements from tungsten by chloroform extraction of their xanthate complexes. Large amounts of copper interfere during the extraction of tungsten because of the precipitation of cuprous thiocyanate. Common ions, including uranium, vanadium, cobalt, titanium, arsenic and tellurium, do not interfere. The proposed method is also applicable to steel.
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PMID:Spectrophotometric determination of tungsten in ores and steel by chloroform extraction of the tungsten-thiocyanate-diantipyrylmethane complex. 1896 41

A spectrophotometric method for the determination of trace amounts of manganese with 1-(2-pyridylazo)-2-naphthol (PAN) is described. The method is based on the measurement of absorbance of the manganese-PAN chelate solubilized with a non-ionic surfactant, Triton X-100. No extraction procedure is required in the method proposed. High concentrations of calcium, aluminium and magnesium do not interfere. The presence of up to 10 ppm of lead can be tolerated. Iron, cadmium, zinc, cobalt and nickel can be effectively masked with potassium cyanide. Beer's law is obeyed up to 2 ppm of manganese. The molar absorptivity of the manganese-PAN chelate found was 4.4 x 10(4) l. mole (-1). cm(-1) at 562 nm. The overall stability constant of Mn(PAN)(2) in 0.4% Triton X-100 medium is 10(16.8).
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PMID:Spectrophotometric determination of manganese with 1-(2-pyridylazo)-2-naphthol and a non-ionic surfactant. 1896 90

N-Methylaminothioformyl-N'-phenylhydroxylamine forms a 1:2 (metal:ligand) greenish yellow complex with cobalt(II). This complex has maximum absorption at 470 nm with a molar absorptivity of 1.65 x 10(4) 1.mole(-1).cm(-1). Beer's law is obeyed over the concentration range 6 x 10(-6)-6 x 10(-5)M. The effect of diverse ions is described.
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PMID:Direct photometric determination of cobalt(II) with N-methylaminothioformyl-N'-phenylhydroxylamine. 1896 30

A simple and rapid ultraviolet spectrophotometric method is proposed for the determination of trace amounts of tungsten(VI) with ammonium 1-pyrrolidinecarbodithioate (APDC). The method is based on measurement of the absorbance of the tungsten APDC complex in fairly concentrated hydrochloric acid medium; no extraction is required. The complex is formed at an initial acidity of 6M hydrochloric acid and has an absorption maximum at 250 nm. The high absorption of the reagent blank at 250 nm disappears on decomposition of excess of reagent by heating. Beer's law is obeyed over the range 0.43-3.2 ppm of tungsten(VI). The molar absorptivity of the complex is 4.5 x 10(4) l.mole(-1) .cm(-1) at 250 nm. Tenfold amounts of aluminium, magnesium, calcium, cobalt, iron(II), lead, silver, sodium and titanium do not interfere in the determination of 50 mug of tungsten (VI).
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PMID:Ultraviolet spectrophotometric determination of tungsten(VI) with ammonium 1-pyrrolidinecarbodithioate. 1896 50


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