The potentiometric titration of mercury(II) with cetylpyridinium chloride

Summary New precipitation titrations have been evaluated for the determination of mercury(II) in acid solution and for mercuric cyanide solutions. In acid or neutral solutions the mercuric ion was converted to the bromo complex by addition of excess potassium bromide. Mercuric cyanide was converted to the tetracyano complex by addition of an excess of potassium cyanide. In both cases the complex anions were titrated potentiometrically vs. 0.01M cetyl-pyridinium chloride. Emf's were monitored with a home-made graphite sensor coated with a solution containing poly(vinyl chloride) and dioctylphthalate in tetrahydrofuran and a single-junction reference electrode.

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Über die potentiometrische Titration von Hg(II) mit Cetylpyridiniumchlorid

Zusammenfassung Neue Verfahren zur Fällungstitration von Hg(II) in saurer Lösung sowie von Lösungen von Quecksilbercyanid wurden angegeben. Quecksilberion wird in saurer oder neutraler Lösung durch Zusatz überschüssigen Kalium-bromids in den Brom-Komplex übergeführt. Quecksilbercyanid wird durch Zusatz überschüssigen Kaliumcyanids in den Tetracyanokomplex umgesetzt. In beiden Fällen werden die komplexen Anionen potentiometrisch gegen 0,01M Cetylpyridinium-chlorid titriert. Die EMK wird mit Hilfe eines selbst hergestellten Graphitsensors, der mit einer Lösung von Polyvinylchlorid und Dioctylphthalat in Tetrahydrofuran überzogen ist, sowie einer Single-junction-Bezugselektrode gemessen.

     

Determination of hypophosphite and phosphite by their reduction of iodine,iodate, or periodate and mercury(I) titration of iodide

A new potentiometric method is adopted for the accurate determination of hypophosphite and phosphite alone or in their mixtures using alcoholic iodine, iodate, and periodate. Hg(I) was used as titrant for the produced iodide in case of using alcoholic iodine as oxidant or for the excess added iodide in case of iodate and periodate as oxidants using silver amalgam as the indicatior electrode. The potential breaks which average 300 mV per 0.1 ml of titrant were sharp enough for precise determination of endpoints, and hence the high accuracy of the present method.     

Consecutive indirect titration of periodate and iodate with EDTA

Periodate and iodate (μmol amounts) are determined successively in the same solution by their selective oxidation of iron(II) at pH 2.0 and in acetic acid, respectively. The resultant iron(III) is titrated with EDTA solution to a sulphosalicylic acid end-point. Bromate—iodate mixture can be titrated similarly.     

Spectrophotometric determination of mercury(II) with sodium sulfite

A photometric procedure is developed for determining mercury(II) in aqueous media. It is based on the reaction of mercury(II) with sodium sulfite giving a product with an absorption maximum at 230 nm. The optimum conditions are found. The procedure allowed 0.5 to 13.0 μg/mL of mercury(II) to be determined for 1 min. The effect of some metal cations is estimated.     

Spectrophotometric determination of periodate, iodate and bromate mixtures based on their reaction with iodide.

A rapid, simple, precise and accurate method is proposed for the determination of ternary mixtures of periodate-iodate-bromate based on their reaction with iodide ion at different pH values. The absorbance was measured at 352 nm. Three sets of reaction conditions were developed. In the first set of conditions, only periodate reacted with iodide, but in the second set the periodate and iodate reacted with iodide and in the third set the three ions reacted with iodide during the first 3 min after initiation of the reaction. The method could be used for individual determinations of periodate, iodate and bromate in the concentration range of 0.05-8.0 microg/ml, 0.05-5.0 microg/ml and 0.2-12 microg/ml, respectively. The data were evaluated by simultaneous equations.     

(n, 2n) reactions in iodate and periodate systems

The chemical consequences of (n,2n) reactions on crystalline sodium iodates and sodium periodates, containing¹²⁷I or¹²⁷I+¹²⁹I, were investigated measuring the initial yields and the post irradiation thermal annealing yields at 90°C for three separated fractions: I+I^o, IO ₃ ^– and IO ₄ ^– . The results show different effects for each system and neither isotope effect nor qualitative differences on thermal annealing were observed. The influence of the nuclear reaction type, of the hot-atom's nature and of the structural and chemical environment are discussed.     

Spectrophotometric determination of sulfite with soluble mercury(II) compounds

Sulfite ion reacts with mercury(II) ion in acid solution to form the mercury(I) ion. The reaction is rapid and quantitative. The mercury(I) ion absorbs at 237 nm with a molar

5. Beer's law Data for Sulfite Complexes of Covalent Mercury(II) Compounds

SO2 (ppm)	?HgCl2a	?HgBr2	?Hg(Ac)2b	?Hg(SCN)2
2.0	12,500	10,000	10,000	9,200
4.0	12,500	11,500	10,000	9,000
6.0	12,500	11,500	10,000	9,200
8.0	12,000	11,000	10,500	9,800

a

Molar absorptivity based on sulfite ion at 230 nm. Solution was 6.86 buffer.

b

Mercuric acetate solutions seemed to be somewhat unstable. absorptivity of about 25,000. The absorbance is linear over a range of approximately 0.5–5.0 ppm as SO₂. Covalent mercury(II) compounds form a complex with sulfite, Hg(SO₃)₂^2?, which absorbs at 230 nm and shows a linear response over a range of 1–8 ppm as SO₂.

     

Spectrophotometric titration of mercury(II) with ethylenedithiodiacetic acid

Summary Mercuric ions may be determined by titration with ethylenedithiodiacetic acid at a wavelength of 260 nm at any pH less than 1. The method is simple, rapid, and selective, and is applicable in solutions of high electrolyte concentration. Mercury(II) can be determined down to 1.5×10^–5 M with a relative standard deviation less than 2%.

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Zusammenfassung Quecksilber (II) läßt sich mit Äthylendithiodiessigsäure bei 260 nm und pH1 titrieren. Das Verfahren ist einfach, rasch und selektiv. Es läßt sich auch für Lösungen mit hoher Elektrolytkonzentration anwenden. Hg(II)-Konzentrationen über 1,5×10^–5 M sind mit einer relativen Standardabweichung unter 2% bestimmbar.

     

Coulometric titration of penicillins and penicillamine with mercury(II)

An absolute coulometric method based on the titration of hydrolysed penicillins with coulometrically generated mercury(II) is presented. An amalgamated gold plate is used as anode and the titration is performed in a pH 4.6 acetate buffer solution. The method gives values which deviate by less than 1% from values obtained by other absolute methods. The relative standard deviation for determination of penicillin G is 0.4%. The determinations of penicillamine and mixtures of penicillamine and penicilloate are also reported.     

The formation and properties of mixed cadmium sulfide—silver sulfide,and mixed mercury sulfide—silver sulfide membranes for electrodes selective to cadmium(II) and mercury(II)

The preparation and behavior of cadmium(II)-selective and mercury (II)-selective electrodes made from mixed metal sulfide-silver sulfide precipitates are discussed. The performance of the cadmium-selective electrode is satisfactory in accordance with similar electrodes described in the literature. Responses to cadmium(II), alone as well as in the presence of complexing agents such as EDTA, NTA, trien and tetren, were determined as a function of pH. Selectivity coefficients are presented. The mercury(II)-selective electrodes generally did not behave reproducibly; at best, the limit of detection was about 10^-5 M.     

On the reaction between iodide and mercury(II)

A survey on the iodide-mercury(II) reaction and its analytical uses is given. Titrations of iodide with mercury(II) in various acidities, using nitrate, acetate, and chloride as titrants and silver or platinum amalgam as the indicator electrode, showed that mercury(II) nitrate is the best titrant giving 0.46 V/0.1 ml potential break in comparison with 0.14 V/0.1 ml of mercury(II) chloride and 0.35V/0.1 ml of mercury(II) acetate, all titrants being 0.05 M in mercury(II).     

Amperometric titration of mercury(II) with EDTA, DTPA and TRIEN in the ppm-range

Summary Mercury(II) can be titrated at pH 2.5–3 with EDTA, DTPA and TRIEN. The titration is followed amperometrically making use of a rotating gold-electrode at a potential of + 0.25 V vs. S.C.E. Especially the use of DTPA allows the determination of small amounts of mercury(II) (down to 1 g). The standard deviation is 2–3%. A correction for the systematic negative error of approximately 4% in the case of EDTA and 8% in the case of DTPA, mainly caused by the faradayic reaction at the electrode, can easily be made.

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Bestimmung von ppm-Mengen Quecksilber(II) durch amperometrische Titration mit ÄDTA, DTPA und TRIEN

Zusammenfassung Quecksilber(II) kann bei pH 2,5–3 mit ÄDTA, DTPA und TRIEN gut titriert werden. Die Titration wird amperometrisch indiziert mit Hilfe einer rotierenden Gold-Elektrode bei einem Potential von + 0,25 V gegen eine gesättigte Kalomelelektrode. Besonders DTPA ermöglicht die Bestimmung von kleinen Mengen Quecksilber(II) (bis etwa 1 g). Die Standardabweichung beträgt 2–3%. Für die systematischen negativen Fehler von etwa 4% bei ÄDTA und 8% bei DTPA, hauptsächlich verursacht durch faradayische Umsetzung an der Elektrode, kann eine einfache Korrektur vorgenommen werden.

Lecture presented at Euroanalysis I Conference, 28. 8. –1. 9. 1972 in Heidelberg, Germany.     

The potentiometric titration of iron(II)/HCl solutions with permanganate

Summary Reagents other than the Zimmerman-Reinhardt reagent have been used to minimize the errors incurred when Fe(II)/HCl systems are titrated with MnO₄ ^–. Potentiometric studies made of the effect of these additives on the initial and equivalence point potentials show that salts whose anions stabilize the Mn(III) state affect the equivalence point potential more than those containing Mn(II). The cation also affects the result, e.g., H₂SO₄ ^– and Na₂SO₄-containing solutions show a greater equivalence potential change than do those containing (NH₄)₂SO₄ and K₂SO₄. Ce₂(SO₄)₃, reportedly an effective inhibitor, does not affect the equivalence point potential. Less titrant is required for 6 M HCl-containing Fe(II) solutions than for 1 M HCl-containing solutions-a result opposite to that expected and only partially explained by a more rapid air-oxidation of Fe(II) in 6 M HCl. The Pt electrode is not inert in this system.

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Zusammenfassung Bei einer Untersuchung der potentiometrischen Titration salzsaurer Eisen(II)-lösungen mit Permanganat wurde die Wirkung der verschiedenen für diese Bestimmung zur Verhinderung von Störungen empfohlenen ZusÄtze geprüft. Dabei ergab sich, da\ Salze, deren Anionen das dreiwertige Mangan stabilisieren, das Potential im Äquivalenzpunkt stÄrker beinflussen als solche, die zweiwertiges Mangan enthalten. Da\ auch das Kation das Ergebnis beeinflu\t ergab sich daraus, da\ bei H₂SO₄ und Na₂SO₄ eine grö\ere PotentialÄnderung im Äquivalenzpunkt beobachtet wurde als bei (NH₄)₂SO₄ und K₂SO₄. Bei Ce₂(SO₄)₃ wurde keine Wirkung auf die PotentialÄnderung festgestellt. Für 6 M salzsaure Fe(II)-Lösungen wurde weniger Titrationsmittel verbraucht als für 1 M salzsaure, was nur zum Teil mit der schnelleren Luftoxydation des zweiwertigen Eisens im 6 M HCl-Lösung erklÄrt werden kann. Die Platinelektrode erwies sich in diesem System nicht als inert.

     

Oscillometric titration of inorganic halides with mercury(II) acetate

Summary The difference between the relative ion mobility of the acetate and halide ions, and the well known slight dissociation of the mercury halides can be used for the titrimetric determination of the inorganic chlorides, bromides and iodides with oscillometric determination of the end-point. Errors in the determination of various halogenides were between 0,2 and 1,4%.

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Oscillometrische Titration von anorganischen Halogeniden mit Quecksilber(II)-acetat

Zusammenfassung Der Unterschied zwischen der relativen Ionenbeweglichkeit der Acetat- und Halogenidionen und die bekannte geringe Dissoziation der Quecksilberhalogenide wurde zur volumetrischen Bestimmung von anorganischen Chloriden, Bromiden und Jodiden mit oscillometrischer Endpunktsanzeige verwendet. Die Fehler bei der Bestimmung verschiedener Halogenide lagen zwischen 0,2 und 1,4%.

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Communicated at the 2nd Conference on Applied physical Chemistry in Veszprém on August 2–5, 1971.     

Hexamminecobalt(III) tricarbonatocobaltate(III) as a redox titrant for the determination of iodide,sulfide, sulfite,and thiosulfate

Summary Hexamminecobalt(III) tricarbonatocobaltate(III) has been used for the determination of iodide. The effect of chloride and bromide, individually and collectively, have also been studied.The determination of sulfide, sulfite and thiosulfate, respectively, with Co(NH₃)₆Co(CO₃)₃ as volumetric oxidimetric titrant has been demonstrated. The respective quantities determined are from 5.84 mg to 195.00g with a maximum standard deviation of 0.91 %, from 24.85 mg to 249.00g with a maximum standard deviation of 0.39 %, and from 12.60 mg to 126.00g with a maximum standard deviation of 0.64%.

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Zusammenfassung Hexaminkobalt(III)tricarbonatokobaltat(III) (A) wurde zur Jodidbestimmung verwendet. Dabei wurde die Wirkung von anwesendem Chlorid und Bromid — einzeln und gemeinsam — untersucht. Die Bestimmung von Sulfid, Sulfit und Thiosulfat mit A als volumetrisches Oxydationsmittel wurde beschrieben. Die bestimmbaren Mengen liegen zwischen 5,84 mg und 195,0g mit einer maximalen Standardabweichung von 0,91 %, zwischen 24,85 mg und 249,0g mit einer maximalen Standardabweichung von 0,39% bzw. zwischen 12,60 mg und 126,0g mit einer maximalen Standardabweichung von 0,64%.

     

Determination of sulfite by reaction with mercury(I) chloride and spectrophotometric measurement of mercury(II) complexes

Sulfite ion was determined in the 0.4 to 12-ppm range by reaction with insoluble mercury(I) chloride to form the soluble Hg(SO₃)₂^staggered2? ion and elemental mercury. The uv absorption of the sulfite complex or an anion species, HgX₄^staggered2?, formed on adding an excess of KBr, KCl, KI, or KSCN is measured. The mercury(II) in solution can also be determined by lowering the pH, adding KCl, and forming the crystal violet adduct of the HgCl₃^staggered? ion. This adduct is extracted into benzene and the absorbance measured at 605 nm.     

Oxidation of tris(1, 10-phenanthroline)iron(II) ion by iodate and periodate ions in neutral medium

The reactions of iodate and periodate with Fe(phen)₃²⁺ have been studied in neutral medium iodate ion is unreactive with ferroin in aqueous solution. The reaction is autocatalytic in the case of IO₄⁻. The autocatalysis disappears in an excess of IO₃⁻. The rate constants of both processes were determined and a reaction mechanism has been proposed. © 1996 John Wiley & Sons, Inc.