Amperometry with two polarisable electrodes-VII: chelometric determination of indium

Optimum conditions have been found for the chelometric determination of indium by biamperometric titration with EDTA. Two stationary platinum electrodes (Pt-Pt) or two graphite electrodes (C-C) may be used to indicate the end-point of the titration. At pH 1-1.5 the determination is highly selective. The applied potential only influences the absolute value of the current ; the accuracy of the determinations remains constant over a wide interval of applied potential. At a potential of 1.0-1.7 V the change of current during a titration with 0.05 M EDTA solution is of the order of 10 microA. Analytical applications of the method are discussed.     

Spectrophotometric titration of bismuth with EDTA

A new spectrophotometnc method for the estimation of bismuth with EDTA, using iron-salicylate complex as the indicator, has been developed. The determinations were carried out by measuring the absorbance at 520 mmu. of solutions containing bismuth, iron(III), salicylic acid and various quantities of EDTA, at pH 0.5. It has been shown from the stability constants of the complexes present that before the end-point iron(III) will not react appreciably with the Bi-EDTA complex. The interference from iron(III) in the estimation of bismuth, which is a serious drawback in many other methods, is eliminated in the present method, as iron(III) acts as the indicator.     

复杂高铋物料中铅的Na2EDTA滴定法测定

复杂高铋物料中,铋、砷、锑、锡四元素含量高且共存时会影响铅的测定。特别是铋含量高时对铅的测定影响大。实验用EDTA—酒石酸联合掩蔽铋、砷、锑、锡,在稀硫酸介质中以硫酸钾为沉淀剂,使铅生成硫酸铅钾复盐沉淀而与铋、砷、锑、锡、铁、铜、锌、铝、钴、镍等干扰离子分离,沉淀以乙酸-乙酸钠浸取,二甲酚橙为指示剂,Na2EDTA滴定法测定铅。试验进一步优化了测定条件,确定最佳条件：硫酸（1 1）加入量为7mL、硫酸钾用量为5g、煮沸时为5min、沉淀陈化时间为2h、EDTA 50g/L 加入量为10mL、酒石酸用量为0.5g,铅的回收率99.70% ～100.65%。将实验方法应用于测定复杂高铋物料中铅,标样BY0111-1与给定值一致,相对标准偏差（n=11）RSD 0.20%～0.23%,满足生产测试要求。     

Determination of total iron in standard rocks by spectrophotometric titration with EDTA

A method for the determination of total iron in silicate rocks is described. It is based on spectrophotometric titration of iron(III) with EDTA after decomposition in a PTFE bomb. No prior separation of interfering elements is needed. The method was tested by analysis of the U.S. Geological Survey reference rocks G-2, AGV-1, GSP-1, BCR-1 and PCC-1. The same sample solutions were also analysed by atomic-absorption spectrophotometry. The agreement with published and recommended values was good.     

Specification of colour changes of metallochromic indicators in the titration of bismuth with EDTA

The quality of the colour changes at the end-point in the complexometric titration of bismuth(III) with EDTA, using the indicators Hemotoxylin, PAN [1-(2-Pyridylazo)-Naphthol-2], PAR [4-(2-Pyridylazo)-Resorcinol], Xylenol Orange and Thoran is studied by means of the CIE 1931 trichromatic system, using specific colour discrimination (SCD) and colour difference (DeltaE*). The indicators are arranged in order of colour change quality. Of the indicators studied, Hemotoxylin is recommended as the most suitable for this titration.     

EDTA titration of bismuth(III) in ores and concentrates with biamperometric indication

Summary A method is described for the chelatometric titration of bismuth(III) with biamperometric indication. It is applied to ores and concentrates and can also be used in presence of interfering elements (as Zr, Tl, In, Mo, Cu, Fe).

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Zusammenfassung Ein Verfahren wird beschrieben zur chelatometrischen Titration von Wismut(III) mit biamperometrischer Endpunktsanzeige. Es wird auf Erze und Konzentrate angewendet und kann auch in Gegenwart störender Elemente (wie Zr, Tl, In, Mo, Cu, Fe) benutzt werden.

     

Na2EDTA反滴定法测定铜镍合金中的镍

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做掩蔽剂,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。方法能很好地分离铜及其他杂质的干扰。试验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0.0456%～0.2409%,加标回收率为99.30%～101.10%如有残渣,过滤之后将残渣消解,用光谱测定不溶渣中的镍含量。能够满足日常样品的检测要求。     

电感耦合等离子体原子发射光谱(ICP-AES)法与EDTA滴定法联用测定含白云岩矿石中氟化钙

氟化钙的测定目前较多采用的是GB/T5195.1-2017和DZG93-05两种方法,前者测定范围≥60%,后者测定范围>3%。两种方法各有优缺点,然而却都无法满足矿石中含有白云岩时的测定。近年来,青海省地勘局大力探寻萤石矿,各矿区矿石组成、矿床类型各不相同,且氟化钙品位高低不一,尤其是青海省海西州喀雅克登矿区中常见萤石矿与白云岩共存,直接采用国家标准方法,测定结果偏高,行业标准方法的精密度和准确度也很难达到要求。本文对方法进行优化,准确称量样品0.2000g至50mL的锥形瓶中,加入10mL含钙冰乙酸(1+9),瓶口放置φ40mm的短颈漏斗,在控温电热板上100℃加热40min,取下过滤,残渣放回原锥形瓶,加入20mL混合酸,瓶口放置漏斗,于控温电热板上150℃微沸30min,将溶液转移至100mL比色管中,摇匀,澄清。在Ca 317.933 nm处,使用电感耦合等离子体原子发射光谱法(ICP-AES)测定氟化钙。根据ICP-AES的测定结果,将氟化钙质量分数大于15%的样品用EDTA滴定法再次测定。按照实验方法测定喀雅克登矿区实际样品,两种方法测定结果的相对标准偏差(RSD,n=11)分别为1.86%和0.77%,加标回收率为97.9%～102.2%,可满足含白云岩矿石中氟化钙的准确测定。     

EDTA滴定法测定分银渣中的铅含量

采用氟化铵-盐酸-硝酸-高氯酸溶解样品,加入氢溴酸除去样品中的砷、锑、锡等共存元素,加入硫酸将样品中的铅转化为硫酸铅沉淀,通过过滤与其它元素分离,滴定前加入巯基乙酸掩蔽铋,在乙酸-乙酸钠缓冲体系下,以二甲酚橙为指示剂,建立了采用EDTA络合滴定法测定分银渣中铅含量的方法。实验方法用于测定分银渣中的铅含量,测定结果的相对标准偏差(RSD,n=11)为0.32%～0.90%,加标回收率为100%～102%。能够满足日常测定需求。     

Chelatometric titration of bismuth with hedta

A new chelatometric method for the determination of Bi in bismuth-base alloys, low-melting alloys and reagent-grade bismuth salts is proposed. It is based on the chelation of Bi(III) with HEDTA, which is added in substoichiometric amount in perchloric acid medium to eliminate the interfering side-reactions of olation and oxolation, followed by pH adjustment and titration at pH 2 with Semi-Xylenol Orange as indicator. It is more selective than the classical EDTA method, and the accuracy and precision are enhanced. The coefficient of variation was found to be ˜ 0.1%.     

沉淀分离EDTA返滴定法测定卡尔多炉渣中的铅量

采用沉淀分离-EDTA返滴定法建立了卡尔多炉渣中铅含量的测定方法,探讨了样品中共存元素干扰及操作细节等因素对分析结果的影响。实验表明,氟化氢铵用量0.10g、硫酸洗涤次数5～6次、陈化时间3h、氨水加入量5mL、乙酸乙酸钠缓冲溶液加入量30mL、微沸时间15～20min时,方法的加标回收率99.8%～100%,两个实际样品测定结果的相对标准偏差(RSD,n=8,分别为0.14%和0.15%。方法准确度高,精密度好。     

Amperometry with two polarizable electrodes. XVI

Summary Conditions for the magnesium determination in alkaline solution by EDTA titration with biamperometric indication were examined. The most preferable pH range was found to be above 9.6. A reliable determination can be carried out in the presence of Ca, Ni, Cu and Co up to the ratio of 11. In the case of higher concentrations of Cu and Ni masking with potassium cyanide can be used. In this case, however, a change of the titration curves occurs.A new method for the determination of water-hardness by biamperometric indication is proposed. It is rapid and accurate and meets the requirements of routine and research work (error: ±1%).

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Zusammenfassung Die Bedingungen für die Magnesiumbestimmung in alkalischer Lösung durch Titration mit ÄDTA bei biamperometrischer Endpunktsanzeige wurden untersucht. Der günstigste pH-Bereich liegt über 9,6. Zuverlässige Bestimmungen können in Gegenwart von Ca, Ni, Cu und Co bis zum Verhältnis 11 ausgeführt werden. Höhere Konzentrationen an Cu oder Ni können mit KCN maskiert werden, wobei allerdings eine Umkehrung der Kurven auftritt.Ein Verfahren zur Wasserhärtebestimmung mit biamperometrischer Indikation wird vorgeschlagen, das schnell durchzuführen ist und genaue Werte liefert (Fehler ±1%).

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Part XV: Vorlíek, J., and P. Peták: Microchem. J. 12, 466–471 (1967).     

沉淀分离-EDTA滴定法测定铜闪速冶炼烟尘中的锌量

称取0.5 g试样,用盐酸、硝酸、硫酸分解,铅以硫酸铅沉淀的形式分离.以过硫酸铵为氧化剂,氨性溶液中沉淀分离铁、锰等共存元素,加氟化物掩蔽铝、硫脲掩蔽铜,调节溶液pH=5.0～6.0,加入碘化钾消除镉的干扰,以二甲酚橙为指示剂,用ED TA标准溶液滴定.将沉淀物重新溶解,用原子吸收光谱法测定其中的锌量.在0.2％ ～1...     

Determination of the oxidation states of bismuth and copper in superconductor Bi-Ca-Sr-Cu-O by oxidation-reduction titration

Summary The oxidation state of the superconductor Bi-Ca-Sr-Cu-O was determined by two procedures. One was ferrous-chromate titration after dissolution of the sample in manganous nitrate solution. The other was the titration after dissolution in ferrous ion solution. The former procedure gives the concentration of a state like pentavalent bismuth and the latter gives the sum of concentrations of a state like pentavalent bismuth and a state like trivalent copper or peroxide. The result of the titration shows that the superconductor oxide has the state like pentavalent bismuth but not like that of trivalent copper. This is a striking contrast to YBa₂Cu₃O_7–y having a high concentration of the latter state. Although the result was compared with X-ray photoelectron spectra, a clear relationship between them was not obtained.

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Bestimmung der Oxidationsstufen von Bismut und Kupfer im Supraleiter Bi-Ca-Sr-Cu-O durch Redoxtitration

     

Determination of EDTA by catalytic amperometric and catalytic potentiometric titration at a small constant current

Summary Amperometric and potentiometric methods at a small constant current were developed to follow the course of catalytic titrations. In ammoniacal medium EDTA was determined by titration with 0.1 M copper(II) chloride in the presence of hydrogen peroxide as the indicator. Amounts of 42.26–126.87 mg of EDTA were determined with a maximal average deviation of 0.55 %. The results obtained are in good agreement with those of comparable methods.

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Bestimmung von ÄDTA mit Hilfe der katalytischen amperometrischen und der katalytischen potentiometrischen Titration bei kleinem konstantem Strom

Zusammenfassung Die amperometrische und die potentiometrische Methode bei kleinem konstantem Strom wurden für die Verfolgung katalytischer Titrationen ausgearbeitet. ÄDTA wurde in Ammoniakmedium mit 0,1 M Kupfer(II)-chlorid in Anwesenheit von Wasserstoffperoxid als Indicator titriert. Mengen von 42,26–126,87 mg ÄDTA wurden mit einer mittleren Abweichung von 0,55% bestimmt. Die Ergebnisse stimmen gut mit denen vergleichbarer Methoden überein.

The authors thank the SIZ for researchs of SAP Vojvodina for the partial financial support of the present work.     

Standardization of EDTA by spectrophotometric titration, with metallic copper as standard

The standardization of EDTA against electrolytically pure copper is described. The copper is dissolved and titrated spectrophotometrically with EDTA at pH 5.0 without an indicator. A relative standard deviation of 0.009% was achieved.     

EDTA滴定法测定FeO42-

利用了FeO42-在酸性条件下的有关反应,以磺基水杨酸为指示剂,建立了用EDTA间接滴定FeO42-的新方法。用于高铁酸盐的制备和使用过程中测定,测定结果与邻菲口罗啉法一致。