Quantitative precipitation of large amounts of sodium as sodium zinc uranyl acetate and its determination by an indirect complexometric method

Up to 40 mg of sodium can be quantitatively precipitated as sodium zinc uranyl acetate if enough reagent of appropriate composition is added to make the concentrations of zinc and uranium in the mother liquor at least 1.25 and 0.14M respectively. In practice, the reagent solution contains 100 g of uranyl acetate and 300 g of zinc acetate per litre and the volume added (ml) must be at least 15 times that of the solution to which it is added or 1.5 times the number of mg of sodium present, whichever is the greater. The triple salt can then be dissolved in water and the zinc selectively titrated with EDTA at pH 5.3, with Xylenol Orange as indicator. The uranium is masked with ammonium fluoride. Most constituents of ceramics and other silicates, including barium, strontium, magnesium, potassium, sulphate, phosphate and arsenate, do not interfere.     

Compleximetric titration of aluminum and zirconium in siliceous materials after alkali fusion of samples

Rapid methods for the determination of zirconium and aluminum in siliceous materials are described. Samples are decomposed by sodium carbonate—sodium borate fusion and dissolved in perchloric acid. The zirconium is titrated directly with standard EDTA solution at 90–95 ° C in 1 M perchloric acid solution with xylenol orange as the indicator. Aluminum is then complexed by boiling with an excess of EDTA and the free EDTA is back-titrated potentiometrically with standard zinc solution. Interference of titanium in the aluminum determination is prevented by lactic acid masking. The methods have been applied successfully to a wide variety of glass-ceramics, refractories and NBS minerals.     

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.     

Complexometric determination of aluminium in iron ore,sinter, concentrates and agglomerates

A method for the complexometric determination of aluminium in iron ore, sinter, concentrates and agglomerates encountered in international trade is described. The sample is fused in a zirconium crucible with a mixed flux of sodium carbonate and sodium peroxide. The fused mass is completely soluble in hydrochloric acid. The R₂O₃ oxides are then precipitated with ammonia and redissolved in hydrochloric acid. Elements such as iron, titanium and zirconium are separated from aluminium by solvent extraction with cupferron and chloroform. After removal of traces of organic matter from the aqueous phase, the solution is treated with an excess of EDTA, which is then back-titrated with zinc solution (Xylenol Orange as indicator). Addition of ammonium fluoride then releases EDTA equivalent to the aluminium and this is titrated with zinc solution. The method is rapid. The precision and accuracy are excellent, and the results comparable with those obtained by the referee method.     

Selective complexometric determination of mercury with sulphite as indirect masking reagent

A complexo-titrimetric method for the determination of mercury(II) in the presence of other metal ions is described, based on the selective masking ability of sulphite ion towards Hg(II). Mercury in a given sample solution is initially complexed with a known excess of EDTA and the surplus EDTA titrated with zinc sulphate solution at pH 5.0–6.0 (hexamine), using xylenol orange (or methylthymol blue) as indicator. An excess of solid sodium sulphite is then added to decompose the Hg(II)-EDTA complex and the released EDTA is titrated with standard zinc sulphate solution. Reproducible and accurate results are obtained for 9.9–99 mg Hg with relative errors < 0.35% and standard deviations < 0.05 mg. The effects of various cations and anions are studied.     

Na2EDTA滴定法测定粗二氧化碲中铅含量

建立了用氢溴酸消除锑、砷、锡干扰,用硫酸将铅形成硫酸铅沉淀,再用EDTA络合滴定法测定粗二氧化碲中铅量的方法。试样用硝酸、盐酸溶解,用硫酸沉淀铅,氢溴酸消除锑、砷、锡的干扰后,过滤分离其他共存元素,以乙酸-乙酸钠缓冲溶液溶解硫酸铅沉淀,在pH=5.0～6.0时,以二甲酚橙作指示剂,用Na_2EDTA溶液滴定溶液中铅含量。实验结果表明,氢溴酸加入量为15mL,酒石酸加入量为10mL,沉淀体积为50～60mL,沉淀时间1h以上时,方法相对标准偏差(RSD)在0.10%～1.1%,加标回收率为97.1%～102%,满足粗二氧化碲中铅量的生产控制检测要求。     

Indirect complexometric determination of palladium(II) using sodium nitrite as a selective masking reagent

A selective complexometric method is described for the determination of palladium, sodium nitrite being used as masking reagent. Palladium(II) in a given sample solution is initially cornplexed with an excess of EDTA and the surplus EDTA is titrated with zinc sulfate solution at pH 4.5–5.5 (acetic acid-sodium acetate buffer), using xylenol orange as indicator. An excess of sodium nitrite is then added, the mixture is shaken well and the EDTA released from the Pd-EDTA complex is titrated with a standard zinc sulfate solution. Results are obtained for 2.5–27.5 mg of Pd with relative errors 0.5% and standard deviations 0.05 mg. The interferences of various ions are studied. The method is applied for the determination of palladium(II) in alloys and complexes.     

Indirect complexometric determination of beryllium

An indirect complexometric method is described for the determination of beryllium, which is selectively precipitated as Be(NH(4))PO(4), then dissolved in HCl, and the solution passed through an ion-exchange column to retain Be and allow PO(4)(3-)to pass through. Phosphate is precipitated as Mg(NH(4))PO(4) and Mg in the precipitate is titrated with EDTA. Be is obtained from the Mg content.     

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。     

Sodium meta-vanadate as volumetric reagent: Iodine monochloride method

In hydrochloric acid medium sodium meta-vanadate was used as a volumetric reagent for the determination of copper, zinc, cobalt, mercury, and lead. Cu⁺², Zn⁺² and Co⁺²were precipitated as complex mercurythiocyanates, Hg⁺² as mercuric zinc thiocyanate and Pb⁺² as Iodide. The thiocyanates were dissolved in concentrated hydrochloric acid and titrated against standard sodium meta-vanadate solution in the presence of iodine monochloride as a pie.oxidizer and catalyst. In titration of the iodide against the meta-vanadate. it was not necessary to add iodine monochloride to the titrant because it is formed during the titration. Chloroform was used as an indicator. It was pink owing to the liberation of iodine during the titration and became pale yellow at the end-point because of the formation of iodine monochlonde.     

EDTA快速滴定法测定矿石中的氧化铝

介绍一种利用二乙基二硫代氨基甲酸钠分离后以EDTA滴定测定矿石中铝的新方法。锰矿样品用Na OH,Na_3PO_4和Na_2O_2混合熔剂熔融,消除Ca,Mg,Ti的干扰,用含无水乙醇的热水浸取,其中的Mn变为Mn O2沉淀析出,干过滤,定容。将滤液中和至弱酸性,加入二乙基二硫代氨基甲酸钠,一些金属阳离子形成难溶水的络合物而分离,再次过滤,一定量的滤液与过量的EDTA标准溶液反应,用锌标准溶液滴定剩余的EDTA,即得氧化铝的含量。该法采用二甲酚橙为指示剂,同时加入少量氯化十六烷基吡啶,滴定终点颜色突变明显,改善了测量精密度,操作易于掌握。样品测定结果的相对标准偏差为0.42%~1.08%(n=5),加标回收率为97.39%~99.94%。分析过程只需滴定一次,且不使用含铅、铜、氟溶液,方法便捷环保。     

Rapid EDTA determination of lead in binary alloys of lead and tin

Binary alloys of lead and tin were dissolved in nitric acid (1 + 1) containing 10% sodium fluoride. The tin(IV) was effectively masked by the fluoride. The lead was quickly and accurately titrated with EDTA in a hexamine-buffered solution, with Xylenol Orange as indicator.     

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.     

Zur chelometrischen Bestimmung von Zink in Konzentraten

Zusammenfassung Zur Zinkbestimmung wird die Probe eines Sphaleritkonzentrates mit Salzsäure zerlegt, danach Salpetersäure zugefügt und abgedampft, wodurch das Blei in ein wenig lösliches Sulfat übergeht. Man bindet Eisen und Spuren Mangan mit Tiron, fällt bei p_H 10 mit Natrium diäthyldithiocarbamidat und extrahiert mit Chloroform. Aus der organischen Schicht extrahiert man Zink zusammen mit vorhandenem Cadmium und Blei mit 1,5 n Salzsäure in die wäßrige Phase zurück und titriert nach Neutralisation mit ÄDTA gegen Eriochromschwarz T, wobei die in der Arbeitsvorschrift angegebene Rücktitration empfohlen wird.

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Summary For the determination of zinc a sample of a sphalerite concentrate is decomposed by hydrochloric acid with subsequent addition of nitric acid and evaporation. Lead remains as insoluble sulphate. To an aliquot of the filtrate tiron is added to mask iron and small amounts of manganese. At p_H 10 zinc is precipitated together with other elements (Cu, Cd, Pb, Bi, Ni, Co) by use of sodium diethyldithiocarbamidate. It is extracted with chloroform and afterwards reextracted together with cadmium and remaining lead by 1,5 N hydrochloric acid. After neutralisation zinc is titrated with EDTA solution using Erichrome Black T as an indicator and employing a backtitration procedure.

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Eine ähnliche Methode zur Antimonbestimmung vgl. Jankovský, J.: diese Z. 201, 325 (1964).     

Complexometric Determination of Zinc(II) Using 2,2′-Bipyridyl as Selective Masking Agent

 An indirect complexometric method is described for the determination of zinc(II) using 2,2′-bipyridyl as masking agent. Zinc(II) in a given sample solution is initially complexed with an excess of EDTA and surplus EDTA is titrated with lead nitrate solution at pH 5.0–6.0 (hexamine), using xylenol orange as indicator. An excess of 2,2′-bipyridyl is then added, the mixture shaken well and the EDTA released from the Zn-EDTA complex is titrated with standard lead nitrate solution. Results are obtained for 3–39 mg of Zn with relative errors ≤ 0.5% and standard deviations ± 0.06 mg. The interference of various ions are studied. The method is applied for the determination of zinc in its alloys and ores. Received October 27, 1998. Revision June 10, 1999.     

Indirect Complexometric Determination of Mercury(II) Using Potassium Bromide as Selective Masking Agent

 A complexometric method for the determination of mercury in presence of other metal ions based on the selective masking ability of potassium bromide towards mercury is described. Mercury(II) present in a given sample solution is first complexed with a known excess of EDTA and the surplus EDTA is titrated against zinc sulfate solution at pH 5–6 using xylenol orange as the indicator. A known excess of 10% solution of potassium bromide is then added and the EDTA released from Hg-EDTA complex is titrated against standard zinc sulfate solution. Reproducible and accurate results are obtained for 8 mg to 250 mg of mercury(II) with a relative error ± 0.28% and standard deviations ≤0.5 mg. The interference of various ions is studied. This method was applied to the determination of mercury(II) in its alloys. Received April 18, 2001 Revision October 10, 2001     

EDTA滴定法测定除尘灰中锌含量

采用灰化后再溶解试样的方法,成功解决了除尘灰因碳含量过高而难于溶解的问题;将灰化后的试样以HCl-HNO3-HF-HClO4混酸溶解,在氯酸钾存在下,以铁盐作载体,用氨水沉淀分离大部分铁、铝、铅等元素,以硫脲-氟化物、硫代硫酸钠、抗坏血酸作掩蔽剂,掩蔽剩余少量铜、锡、铁等干扰元素,在pH=5.5~6条件下,以二甲酚橙为指示剂,用EDTA标准溶液滴定得到锌的含量。方法的相对标准偏差在0.75%~2.8%,加标回收率在98.0%~102%。方法操作简便,且分析结果准确度、重现性较好,可以满足生产检验的需要。     

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).     

Indirect complexometric determination of palladium usingl-histidine as masking agent

An indirect complexo-titrimetric method is described for the determination of palladium in the presence of other metal ions, L-histidine being used as the masking agent. Palladium(II) and other metal ions are initially complexed with an excess of EDTA and the surplus EDTA titrated with standard zinc sulfate solution at pH 4.5–5.5 using xylenol orange as indicator. An excess of 1 % L-histidine solution is then added, and the released EDTA is titrated with standard zinc sulfate solution. Accurate and reproducible results were obtained for 2–15 mg of Pd with relative errors 0.4% and standard deviations < 0.02mg. Sn(IV) and Au(III) interfere, but can be easily masked. The method is successfully applied for the determination of palladium(II) in alloy compositions.     

The complexometric determination of bromides and bromates in the presence of each other

Summary A complexometric titration method is described for the determination of bromides and bromates in the presence of each other. Bromides are precipitated as silver bromide, the precipitate dissolved in a solution of potassium tetracyanoniccolate and the displaced nickel titrated by means of a EDTA solution. Bromine is determined indirectly: two atoms of bromine correspond to one of nickel. The bromates are reduced to bromides and the sum of the bromides are determined by the described method. The difference of burette readings gives the bromides obtained by reduction of bromates. The method gives good results with mixtures of bromides and bromates in the ratio of 1 20 and vice versa.