Ethyleneglycol-bis(aminoethyl)tetraacetic acid in the amperometric titration of cadmium in the presence of zinc

Cadmium can be titrated amperometrically with EGTA in the presence of zinc; three modifications of the titration are described. The diffusion current of cadmium may be used to follow the titration at —0.90 or —0.70 V vs, the S.C.E, in ammoniacal or acetate-buffered medium respectively The titration may also be performed in ammoniacal solution at —0.30 V vs. the S.C.E., using copper as the amperometric indicator. The influence of iron, aluminium, magnesium, alkaline earths and lead was studied. Ascorbic acid could be used to mask iron and as an effective remover of oxygen. Under appropriate conditions cadmium could be titrated in the presence of 500-fold amounts of zinc. The titration error is approximately 0.002–0.003 ml of a 0.1 M titrant solution.     

Direct complexometric determination of aluminium in "alzinoy"

A simple and precise method for the complexometric determination of aluminium in "Alzinoy" (a binary alloy of aluminium and zinc) is described. After dissolution of the sample in hydrochloric acid, aluminium, zinc and any lead and iron are complexed with excess of EDTA. The excess of EDTA is titrated with lead solution, with Xylenol Orange as indicator. Ammonium fluoride is then added to decompose the Al-EDTA complex, and the EDTA liberated is titrated with lead solution. Four samples can be analysed in about 45 min.     

Na2EDTA返滴定法测定铜镍合金中的镍含量

采用Na₂EDTA返滴定法测定铜镍合金中的镍含量,用柠檬酸钠、硫代硫酸钠和酒石酸作掩蔽剂,丁二酮肟沉淀分离,以二甲酚橙为指示剂,加入过量的Na2EDTA,用氯化锌标准溶液返滴定,能很好地分离铜及其他杂质的干扰。方法用于测定铜镍合金中的镍含量,测定结果的相对标准偏差(RSD,n=9)为0.046%~0.24%,加标回收率为99.3%~101%。能够满足日常样品的检测要求。     

2-(3,5-二溴-2-吡啶偶氮)-5-二乙氨基苯酚作络合滴定指示剂连续测定铁和铝

对2-(3,5-二溴-2-吡啶偶氮)-5-二乙氨基苯酚作铁(Ⅲ),铜(Ⅱ)的配位滴定指示剂进行了研究.在pH1.8～2.0时用EDTA标准溶液滴定铁(Ⅲ).在滴定铁(Ⅲ)后的溶液中,加入对铝过量的EDTA标准溶液,在pH3.8～4.0煮沸下,铝(Ⅲ)与EDTA生成稳定的络合物,过量的EDTA用硫酸铜标准溶液滴定,从而测定铝(Ⅲ).     

The use of naphthidine as indicator in the determination of zinc in metallurgical analysis

Using naphthidine as an internal indicator in the titration of zinc with standard potassium ferrocyanide solutions, suitable procedures are recommended for the determination of zinc in various non-ferrous alloys and in rubber ashes. With aluminium alloys, aluminium bronzes and white metals the zinc is separated from interfering elements by hydrogen sulphide procedures, whereas with tin bronzes the separation is best accomplished by an 8-hydroxyquinoline procedure. After the solution of rubber ashes in hydrochloric acid, the major interfering elements are removed from the zinc by filtration after making the solution ammoniacal. With samples giving large precipitates with ammonia, it is necessary to redissolve them and determine the entrained traces of zinc.     

Contributions to the basic problems of complexometry-XXV Determination of rare earths and phosphate without separation

A new method for coraplexometric determination of rare earths (RE) and phosphate without prior separation is described. It is based on indirect determination of RE by back-titration of an excess of DTPA with zinc solution, with Xylenol Orange as indicator. After the titration an excess of La-EDTA complex solution is added and the solution is titrated again with zinc at 40-50 degrees . During this titration lanthanum is displaced from its complex and precipitated as phosphate: LaY(-) + Zn(2+)+ PO(4)(3-) = LaPO(4) + ZnY(2-). The consumption of zinc solution corresponds to the amount of phosphate.     

A rapid complexometric scheme for analysis of iron, aluminium, calcium and magnesium in slags

A simple and rapid complexometric method has been developed for the simultaneous determination of iron, aluminium, calcium and magnesium in a single solution in slags. Phosphorous and small amounts of chromium (1.5 mg) and vanadium (1 mg) do not interfere in the titration. Titanium and manganese are suitably masked with lactic acid and tetra sodium pyrophosphate, respectively. In a suitable aliquot, iron is titrated at pH 2 with EDTA, using sulphosalicylic acid as indicator. To this solution, excess disodium 1,2-cyclohexane diamine tetra acetic acid (DCTA) is added and aluminium is titrated by titrating the excess DCTA with standard copper sulphate solution at pH 3.5, using 1-(2-pyridylazo)-2-naphthol (PAN) as an indicator. A known excess of EDTA is added, the pH is raised to 10 and calcium and magnesium are jointly titrated by titrating the excess EDTA with copper sulphate solution, using PAN indicator. The Ca-EDTA complex is demasked with ammonium oxalate at pH 5 and the released EDTA equivalent to calcium is titrated with copper sulphate solution at pH 10 with PAN indicator. Results of analysis compare favourably with certified values and values obtained by standard methods for BCS and other slags. A set of five samples can be analysed for iron, aluminium, calcium and magnesium in four hours as compared to three days by the classical conventional method.     

Selective edta titration of gallium or aluminium in the presence of other metals

The selective determination of aluminium or gallium by EDTA titration is reported. Gallium or aluminium is titrated together with other multivalent ions with EDTA at pH 3-7 and then the pH is raised above 10.5. Aluminates or galliumates are formed with the consequent release of EDTA from the EDTA complexes. The released EDTA is titrated with lead solution using Xylenol Orange as an indicator and with copper using photometric detection of the end-point, for the determination of gallium and aluminium respectively. The theoretical basis of the procedure is discussed.     

A new radiometric titration method based on separation by means of ion exchange

A mathematical expression is derived for the radiocomplexometric determination of a mixture of two metals with one ligand, using an anion exchanger in the solution as a phase separating system. An expression is also given for the complexometric titration of a metal, when formation of acidic or basic complexes is taken into account. In the experimental part titration procedures are proposed for determinations of nickel, copper and iron, using⁶⁵Zn as indicator. The formation of the acidic complex, ZnHY, does affect the radiometric titration curve of zinc with EDTA.     

Rapid chelatometric determination of bismuth, titanium and aluminium using Semi-Xylenol Orange with visual end-point indication

A rapid and simple general complexometric method was presented for the determination of bismuth, titanium and aluminium in laboratory synthesized alloys similar to those of some bauxites, clay, ilmenite, Portland cements and ceramic products. The precision and accuracy attainable in successive titrations of Bi(3+), Ti(4+) and Al(3+) with 0.01 and/or 0.001M solutions of disodium ethylenediaminetetraacetate (Na(2)EDTA) and standard ZnCl(2) of the same concentration, using Semi-Xylenol Orange (SXO) as a metallochromic indicator with visual end-point indication were studied. For one aliquot Bi(3+) was at first directly titrated at pH 1-2 (HNO(3)) with Na(2)EDTA using SXO as indicator in the presence of L-ascorbic acid to reduce Fe(3+) to Fe(2+). At the bismuth end-point, an excess of Na(2)EDTA was added, the pH was adjusted with hexamine buffer (pH 5) and the excess of Na(2)EDTA was back-titrated with solution of standard zinc(II) chloride for both the simultaneous and consecutive titrations in the presence of (SXO) as indicator. For the simultaneous titration, fluoride was added to release the Na(2)EDTA combined with both Al(3+) and Ti(4+). For the consecutive titration, phosphate was added to release the Na(2)EDTA combined with Ti(4+) and then fluoride to release the Na(2)EDTA combined with Al(3+). The interference of various anions and cations in the determination of Bi(3+), Ti(4+) and Al(3+) was studied. A comparison of the accuracy of both the simultaneous and consecutive titration was also carried out. The proposed methods were applied successfully to some real samples of bauxites, clay, ilmenite, Portland cements and ceramic products and the results were satisfactory.     

Eine neue Apparatur zur kontinuierlichen Titration

The sample of a process stream is mixed with the indicator. Then—while being stirred—it is pumped continuously through a channel in a block of transparent material where the titration solution is added through a slit or a row of narrow holes ranging over the entire length of the channel. The end of the titration is marked by a very distinct change of colour, indicating by its position the concentration of the process stream.     

Analytical aspects of some organic acids

Summary Back titrimetric procedures for the estimation of aluminium, zirconium, and thorium have been developed, which involved the adjustment of the concentration of the metallic salts, concentration of EDTA,ph, and temperature, addition of indicator solution (namely, 2-hydroxy3-naphthoic acid and back titration with standard 0.1 M ferric chloride solution. This method is based on the fact that the excess EDTA, which is added to the metal solutions may be back titrated with iron(III), which forms a highly coloured complex with the indicator, when present in slight excess. Quantities of aluminium, zirconium and thorium as small as 10.8, 4.6, 11.6 mg respectively, can be back titrated with in experimental error, when present in a volume of 100 ml.Part IV: See Z. analyt. Chem. 172, 356 (1960).     

EDTA滴定法测定含锌物料中氧化锌

采用氯化铵-氨水体系溶解试样,干过滤后,向移取的滤液中加入氯化钡和硫酸共沉淀铅离子,过滤分离硫酸铅沉淀,向滤液中加人抗坏血酸、氟化钾、硫代硫酸钠等掩蔽剂掩蔽少量干扰元素。在pH=5~6的乙酸-乙酸钠缓冲溶液中,以二甲酚橙为指示剂,用EDTA标准滴定溶液滴定测得结果为氧化锌、水溶性锌和镉合量,扣除由原子吸收光谱法测得的水溶性锌量和镉量,即为氧化锌量。对总氨浓度、氯化铵-氨水浓度比、溶液加入量、搅拌时间、共存离子干扰、精密度等进行了实验,建立了EDTA滴定法测定含锌物料中氧化锌物相的分析方法。实验证明,氧化锌含量在24%~83%时,方法精密度(RSD)为0.25%~0.54%,加标回收率在99%~104%,完全满足含锌物料中氧化锌的测定要求。     

Komplexometrische titration von vierwertigem uran

A comploxomutric titration is described for the determination of uranium(IV). Solochrome Black 6BN is used as indicator. The reduction of Uranium(VI) is performed with zinc in hydrochloric acid solution.     

Selective masking and demasking for the stepwise complexometric determination of aluminium,lead and zinc from the same solution

Background  

A complexometric method based on selective masking and de-masking has been developed for the rapid determination of aluminium, lead and zinc from the same solution in glass and glass frit samples. The determination is carried out using potassium cyanide to mask zinc, and excess disodium salt of EDTA to mask lead and aluminium. The excess EDTA was titrated with standard Mn(II)SO₄ solution using Erichrome Black-T as the indicator. Subsequently selective de-masking agents – triethanolamine, 2,3-dimercaptopropanol and a formaldehyde/acetone mixture – were used to determine quantities of aluminium, lead and zinc in a stepwise and selective manner.     

Titrimetrische Bestimmung des Aluminiums in Silicatgesteinen mit potentiometrischer Indikation

Zusammenfassung Eine titrimetrische Aluminiumbestimmung in Silicatgesteinen mit potentiometrischer Indikation wird beschrieben. Ein Vergleich der Analysenergebnisse mit denen anderer Verfahren sowie die nach den Methoden der Fehlerrechnung erhaltenen Zahlenwerte beweisen die Brauchbarkeit des Verfahrens. Der Aufschluß des Probenmaterials erfolgt mit Flußsäure/Perchlorsäure. Die Störelemente Eisen, Titan und Zirkon werden mit Kupferron-Chloroformlösung aus stark salzsaurer Lösung extrahiert. Zum wäßrigen Extrakt wird 0,01 M ÄDTA-Lösung gegeben und der Überschuß mit 0,01 M Zinksulfatlösung potentiometrisch gegen Hexacyanoferrat(II)/(III) als Indicatorsystem zurücktitriert. Die Titration erfolgt automatisch. Das Verfahren benötigt keinen Farbindicator und ermöglicht daher auch die Aluminiumbestimmung in gefärbten Lösungen. Die Erfassung des Titrationsendpunktes ist objektiv.

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Titrimetric determination of aluminium in silicate rocks by potentiometric indication

A comparison of the analysis results with those of other methods and especially the numerical values according to the methods of the error calculation, prove the usefulness of the method described. The decomposition of the test material is carried out with hydrofluoric acid/perchloric acid. The interfering elements iron, titanium and zirconium are extracted from a strong hydrochloric acid solution by means of a cupferron-chloroform solution. 0.01 M EDTA solution is added to the aqueous extract, and its excess is back-titrated potentiometrically with 0.01 M zinc sulphate solution against hexacyanoferrate(II)/(III) solution as an indicating system. The titration takes place automatically. The method requires no colour indicator, thus allowing the determination of aluminium in coloured solutions, too. The registration of the end point of the titration gives a detached result.

     

An improved selective determination of mercury(II) by complexometric titration

A simple and accurate method has been developed for selective determination of mercury in alkaline solution. It involves the addition of an excess of EDTA to the mercury solution, titration of unreacted EDTA with a standard zinc solution, and then addition of N-allylthiourea solution at pH ? 9. By heating, the mercury-EDTA chelate is decomposed selectively, mercury sulfide is precipitated, and the EDTA freed is again titrated with standard zinc solution. Eriochrome Black T is used as indicator. Interference of some cations is discussed.     

Use of nitrosochromotropic acid as a metal indicator

Summary Nitrosochromotropic acid and copper give a purple coloured complex in the pH range 5.8–6.5, which is less stable than Cu(II)-EDTA complex. When milligramme quantities of copper solution containing few drops of nitrosochromotropic acid were titrated with EDTA the colour changes to light green or colourless. Copper can be titrated from 15–30° C, but at higher temperature low results are obtained due to dissociation of copper complex. Alkaline earths do not interfere in the titration of copper, but zinc, cadmium, nickel, cobalt, aluminium and iron(III) interfere. The interference of aluminium and iron(III) is masked by sodium fluoride. Microtitration can be carried out using nitrosochromotropic acid screened with xylene cyanol FF as metal indicator.     

Determination of zinc in blast furnace flue dusts

Two methods for the determination of zinc in blast-furnace flue dusts are described. One involves a solvent extraction step using methyl isobutyl ketone to separate the zinc from the bulk of the interfering elements, followed by a complexometric titration of the zinc with EDTA, using Eriochrome Black T as indicator. The other employs differential pulse polarography with a hydrochloric acid + pyridine supporting electrolyte. In this method, the interference of iron is prevented by reducing it with hydroxylamine hydrochloride; aluminium is complexed with potassium fluoride. Other elements, with the exception of cobalt, do not interfere. Excellent agreement between the two methods is obtained in the range 0.01–0.6% zinc.     

Vergleich dreier komplexometrischer aluminiumbestimmungsmethoden

The complexometric methods for determination of aluminium of Wännien and Ringbom, P?ibil and Sajo are compared. That of P?ibil has a relative error of — 0.3% and a variance of 0.7% in the region of 2.5 mg Al and is preferable. The salt error for sodium acetate, urotropin, sodium chloride, nitrate and sulfate has been studied for the titration with xylenol orange as indicator (P?ibil). The rate of formation of the aluminium complex in strongly acidic medium has been studied in relation to the boiling time.