Soluble manganese(IV) as a chemiluminescence reagent for the determination of opiate alkaloids, indoles and analytes of forensic interest

We present the results of our investigations into the use of soluble manganese(IV) as a chemiluminescence reagent, which include a significantly faster method of preparation and a study on the effect of formaldehyde and orthophosphoric acid concentration on signal intensity. Chemiluminescence detection was applied to the determination of 16 analytes, including opiate alkaloids, indoles and analytes of forensic interest, using flow injection analysis methodology. The soluble manganese(IV) reagent was less selective than either acidic potassium permanganate or tris(2,2′-bipyridyl)ruthenium(III) and therefore provided a more universal chemiluminescence detection system for HPLC. A broad spectral distribution with a maximum at 730 ± 5 nm was observed for the reaction between the soluble manganese(IV) and a range of analytes, as well as the background emission from the reaction with the formaldehyde enhancer. This spectral distribution matches that reported for chemiluminescence reactions with acidic potassium permanganate, where a manganese(II) emitting species was elucidated. This provides further evidence that the emission evoked in reactions with soluble manganese(IV) also emanates from a manganese(II) species, and not bimolecular singlet oxygen as suggested by previous authors.     

A contribution to the use of tetravalent manganese in solutions of sulfuric acid as an oxidimetric reagent

The preparation of solutions of manganese(IV) sulfate in 9 M sulfuric acid as well as the stability of these solutions was studied for 0.00501 M concentration of manganese(IV) ions. Potentiometric titration of solutions of primary standard substances, potassium iodide and sodium hexacyanoferrate, was recommended for determining the titer of 0.005 M reagent solutions. It was verified that manganese(IV) sulfate can be used for determining low concentrations of organic substances by direct titration determination of hydroquinone, p-aminophenol, and metol and by indirect determination of oxalic acid.     

The Permanganate Oxidation of Triethylamine; Evidence for the Formation of Manganate Ion in Potassium Permanganate/Triethylamine Reagent

The active oxidant of KMnO_4/Et₃N reagent has been verified as potassium manganate by ultraviolet spectrometry, and the final oxidation product as manganese(IV) oxide by iodometric titration.     

The role of manganese(IV) compounds as oxidants - a review

A historical review of the development of manganese(IV) chemistry and its application in analytical chemistry is presented. A brief presentation of the presence and importance of manganese(IV) in other areas of chemistry is also given.     

The application of strongly oxidizing agents in flow injection analysis : Part 2. Manganese(III)

The application of manganese(III) as a powerful oxidizing agent in flow injction analysis is described. Manganese(III) is generated electrochemically in the flowing system at a working electrode consisting of a packed bed of gold powder. Spectrophotometric detection is used at 490 nm, where manganese(III) in sulphuric acid solution absorbs strongly. Undr the experimental conditions, the generation of manganese(III) can be accompanied by generation of manganese(IV) and permanganate; manganese(III) alone can be generated by a proper selection of the generating current and the flow rate. Results are presented for the determinatin of various organic and inorganic substances by means of manganese(III), usually at concentrations in the 10^?4—10^? mol l^?1 range. Unlike permanganate and manganese(IV), manganese(III) does not react with chloride, so that oxidizable compounds can be determined in the presence of large amounts of this species.     

Bestimmung organischer Stoffe durch Oxydation mit Permanganat

Zusammenfassung Die Wirkung von Permanganat, Mangan(IV)-oxid und dem Pyrophosphatkomplex des dreiwertigen Mangans auf Oxalsäure wurde verglichen. Die Oxydation zu Kohlendioxid und Wasser verläuft mit frisch bereitetem Mangan(IV)-oxid in einem breiten Aciditätsbereich sofort und quantitativ. Die Oxydation mit Permanganat und mit dem Pyrophosphatkomplex des dreiwertigen Mangans verläuft langsamer. Im Falle des letztgenannten Reagens wird ein quantitativer Verlauf der Reaktion in 2 N schwefelsaurer Lösung bei Laboratoriumstemperatur nach 20 min erreicht.

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Summary The effect of permanganate, manganese dioxide and of the pyrophosphate complex of trivalent manganese on oxalic acid has been compared. The oxidation of oxalic acid to carbon dioxide and water takes place immediately and quantitatively in a wide acidity range when freshly prepared manganese dioxide is used. Oxidation with permanganate and the manganese(III)-pyrophosphate complex is slower. With the latter reagent, a quantitative reaction is achieved only after 20 min at laboratory temperature in a medium of 2 N sulphuric acid.

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VII. Mitteilung: Mikrochim. Acta1968, 405.     

Determination of nitrate in sea water

Nitrate in sea water is determined by reduction to nitrite with zinc metal in ammoniacal solution in the presence of manganese (IV) as catalyst. The effects of hydrogen ion concentration, reduction temperature, reaction time and the order of reagent addition are discussed. The nascent nitrite diazotizes with sulfanilamide and is then coupled by N-1-naphthylethylenediamine in acid medium forming a diazo-dye which is measured spectrophotometrically.     

Synthesis, characterization, and solution properties of a novel cross-bridged cyclam manganese(IV) complex having two terminal hydroxo ligands

A novel monomeric tetravalent manganese complex with the cross-bridged cyclam ligand 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (Me2EBC), [Mn(IV)(Me2EBC)(OH)2](PF6)2, was synthesized by oxidation of Mn(II)(Me2EBC)Cl2 with H2O2 in the presence of NH4PF6)in aqueous solution. The X-ray crystal structure determination of this manganese(IV) compound revealed that it contains two rare terminal hydroxo ligands. EPR studies in dry acetonitrile at 77 K show two broad resonances at g = 1.96 and 3.41, indicating that the manganese(IV) exists as a high-spin d3 species. Resonance Raman (rR) spectra of this manganese(IV) species reveal that the dihydroxy moiety, Mn(IV)(OH)2, is also the dominant species in aqueous solution (pH < 7). pH titration provides two pK(a) values, 6.86(4) and 10.0(1), associated with stepwise removal of the last two oxygen-bound protons from [Mn(IV)(Me2EBC)(OH)2](2+). The cyclic voltammetry of this manganese(IV) complex in dry acetonitrile at 298 K demonstrates two reversible redox processes at +0.756 and -0.696 V (versus SHE) for the Mn4+/Mn3+ and Mn3+/Mn2+ couples, respectively. This manganese(IV) complex is relatively stable in weak acidic aqueous solution but easily degrades in basic solution to manganese(III) derivatives with an 88 +/- 1% yield.     

Determination of phosphite,hypophosphite, tellurium and mercury

A new catalytic oxidation procedure, involving the use of a cerium(IV) sulfate reagent in perchloric acid with a mixed silver(I)—manganese(II) perchlorate catalyst, has been developed for the determination of phosphite, hypophosphite, and tellurium. By this method 15—100 mg of phosphite, 5—35 mg of hypophosphite, and 10—105 mg of tellurium may be determined with standard deviations of ±0.17, ±0.32, and ±0.21% respectively. A direct titration procedure for mercury(I) is described using a ceric perchlorate solution as titrant with the mixed catalyst system. Samples from 65–510 mg may be analyzed with a standard deviation of ±0.36%.     

The importance of chain length for the polyphosphate enhancement of acidic potassium permanganate chemiluminescence

Sodium polyphosphate is commonly used to enhance chemiluminescence reactions with acidic potassium permanganate through a dual enhancement mechanism, but commercially available polyphosphates vary greatly in composition. We have examined the influence of polyphosphate composition and concentration on both the dual enhancement mechanism of chemiluminescence intensity and the stability of the reagent under analytically useful conditions. The average chain length (n) provides a convenient characterisation, but materials with similar values can exhibit markedly different distributions of phosphate oligomers. There is a minimum polyphosphate chain length (∼6) required for a large enhancement of the emission intensity, but no further advantage was obtained using polyphosphate materials with much longer average chain lengths. Providing there is a sufficient average chain length, the optimum concentration of polyphosphate is dependent on the analyte and in some cases, may be lower than the quantities previously used in routine detection. However, the concentration of polyphosphate should not be lowered in permanganate reagents that have been partially reduced to form high concentrations of the key manganese(III) co-reactant, as this intermediate needs to be stabilised to prevent formation of insoluble manganese(IV).     

Mangan(IV)-Komplexe mit dreizähnigen diaciden Liganden. Kristallstruktur von Acetylacetonato-salicylaldehydbenzoylhydrazonato(2−)-methanol-mangan(III)

Manganese(IV) Complexes with Tridentate Diacidic Ligands. Crystal Structure of Acetyl-acetonato-salicylaldehydebenzoylhydrazonato(2?)-methanol-manganese(III) The manganese(IV) chelates of salicylaldehyde benzoylhydrazone and salicylaldehyde salicylhydrazone were synthesized by ligand exchange reactions using bis(acetylacetonato)manganese(II), tris(acetylacetonato)manganese(III) as well as manganese(III) acetate. The brown complexes show the expected molecular ions in the APCI mass spectra. As an intermediate compound acetyacetonato-salicylaldehydebenzoylhydrazonato(2?)-methanol-manganese(III) was isolated and characterized by X-ray structural analysis. Crystallographic data see “Inhaltsübersicht”.     

Axial Ligand Effects on the Redox Reactions of Manganese Porphyrins

A systematic study for the effect of axially coordinated monovalent anions on the electrode reactions of several manganese porphyrins in acetonitrile is presented. Potential shifts of the metal-centered reduction with changes in counterion were related to the degree of Mn(III)-counterion interaction. In the electrochemically induced ligand exchange, perchlorate anion replaces the other anions as axial ligand coordinated to Mn(III) at oxidation potential less than the first oxidation of manganese porphyrins. Formation constants for axial ligation of OH^? are calculated. One-electron oxidation of dihydroxide coordinated manganese porphyrins generate oxomanganese(IV) porphyrin complexes electrochemically. O=Mn^IVOEP(OH) is more thermodynamically stable than O=Mn^IVTPP(OH), while O=Mn^IVTpFPP(OH) cannot be generated electrochemically. In the presence of styrene or cyclohexene, the absorption spectra of oxomanganese(IV) porphyrins are changed to form manganese(III) porphyrins gradually, which indicates the oxygen atom transfer from oxomanganese(IV) porphyrins to the substrates.     

Coulometric redox titrations of hydrazine,phenylhydrazine and isoniazid with electrogenerated lead(IV) acetate and manganese(III) acetate in acetic acid

Summary The conditions fox coulometric determination of small quantities of hydrazine, phenylhydrazine and isoniazid in glacial acetic acid with electrogenerated manganese(III) acetate and lead(IV) acetate were investigated. With the direct coulometric method at room temperature, good results were obtained in the determination of hydrazine and isoniazid with lead(IV) acetate and in the determination of phenylhydrazine with manganese(III) acetate. Hydrazine and isoniazid can also be determined by the coulometric back-titration method if the oxidation with manganese(III) acetate is performed at elevated temperature.

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Zusammenfassung Die Bedingungen für die coulometrische Bestimmung kleiner Mengen Hydrazin, Phenylhydrazin und Isoniazid mit elektrolytisch erzeugtem Mangan(III)-Acetat und Blei(IV)-Acetat in Eisessig wurden untersucht. Bei Zimmertemperatur wurden gute Resultate durch direkte coulometrische Titration des Hydrazins und Isoniazids mit Blei(IV)-Acetat und bei Titration des Phenylhydrazins mit Mangan(III)-Acetat erhalten. Durch coulometrische Rücktitration können bei höheren Temperaturen Hydrazin und Isoniazid mit Mangan(III)-Acetat erfolgreich bestimmt werden.

     

Speciation of iron and manganese in dam water particles using electron spectroscopy for chemical analysis (ESCA)

The speciation of iron and manganese compounds retained by membrane filtration of dam water samples was studied by use of electron spectroscopy for chemical analysis (ESCA). Samples were taken at various depths and times of year from North Pine Dam near Brisbane, Australia. Both surface and bulk properties of samples representative of the water column profile were investigated. ESCA results showed that iron(III) compounds were found to predominate in the whole water column in any season of the year while the significance of iron(II) species varied in the hypolimnion (the bottom layer). In summer, although various ratios of manganese(II), manganese(III) and manganese(IV) compounds were found to occur down the water column, manganese(IV) compounds were predominant in the epilimnion (the top layer), while both manganese(II) and (IV) compounds predominated in the metalimnion (the middle layer) and the hypolimnion. The majority of Mn(IV) compounds were found throughout the water column after heavy rain and winter season. The ratios of atomic concentrations of iron and manganese as determined by atomic absorption spectrophotometry and ESCA are also discussed.     

Studies on the interference of EDTA in the titrimetric determination of iron(II)

Summary Suitability of vanadium(V), manganese(VII), cerium(IV) and chromium(VI), as oxidants in the titration of iron(II) in the presence of EDTA has been investigated and vanadium(V) has been found to be the best one for that purpose, as titration with this reagent is not influenced by any interference. Cerium(IV) can be used provided phosphoric acid or bismuth nitrate is added to eliminate the interference by EDTA. Chromium(VI) is useful only in the presence of bismuth salt. This effect of bismuth nitrate is not observed in hydrochloric acid medium. Manganese(VII) cannot be used even in the presence of bismuth nitrate, since manganese(II) catalyses the reaction between manganese(VII) and even the metal bound EDTA. Optimum conditions for the quantitative photochemical reduction of iron(III) by EDTA are established.

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Zusammenfassung Die Eignung von V^V,Mn^VII,Ce^IV und Cr^VI zur Titration von Eisen(II) in Gegenwart von ÄDTA ist untersucht worden. V^V hat sich am besten bewährt und ist keinen Störungen ausgesetzt. Ce^IV kann bei Zusatz von Phosphorsäure oder Wismutnitrat benutzt werden. Cr^VI nur bei Gegenwart von Wismutsalz. Die Wirkung von Wismutnitrat konnte in salzsaurem Medium nicht beobachtet werden. Mn^VII kann auch bei Gegenwart von Wismutsalz nicht verwendet werden, da Mn^II sogar die Reaktion zwischen Mn^VII und dem metallgebundenen ÄDTA katalysiert. Die optimalen Bedingungen für die quantitative photochemische Reduktion von Eisen(III) mit ÄDTA wurden ausgearbeitet.

     

Promoting effect of iodide on the hexacyanomanganate(IV)-arsenic(III) redox reaction, for kinetic determination of iodide

The rate of the reaction between hexacyanomanganate(IV) and arsenic(III) in an acid medium is strongly accelerated by iodide. The reaction kinetics indicates that the iodide activity decreases throughout the reaction, probably because manganese(IV) oxidizes iodide to iodate (an inactive form). This behaviour is defined as promotion, rather than catalysis, and this rate-modifying effect has been used to determine iodide by a kinetic method. A linear calibration plot was obtained by a two-point fixed-time procedure. A detection limit of 0.2 ng/ml, a quantification limit of 0.6 ng/ml and relative standard deviations of 5.5 and 13% for the 6.7 and 0.6 ng/ml levels respectively have been found. Positive kinetic interferences from osmium(VIII) and iodate have been observed, and copper(II), silver(I) and mercury(II) inhibit the iodide activity by precipitaton. The method has been applied to determination of iodide in sodium arsenite (reagent grade) and table salt. The method has been validated by recovery experiments.     

The formation of self-assembled monolayers of thiophthalocyanine complexes of titanium, vanadium and manganese and their use in l-cysteine electrocatalysis

Self-assembled monolayers (SAMs) based on octapentylthiophthalocyanine complexes of oxovanadium (IV) (OVOPThPc), titanium(IV) (OTiOPThPc), and manganese (III) acetate (AcMnOPThPc), and of tetraphenylthiophthalocyanine complexes of hydroxo manganese(III) (OHMnTPPc) and oxotitanium(IV) (OTiTPPc) are described. The oxidation of l-cysteine was observed at potentials which ranged from 0.52 V to 0.67 V. The detection limits for l-cysteine analysis were of the order of 10^− 7 to 10^− 6 M.     

Grafting Vinyl Monomers onto Silk Fibers. V. Graft Copolymerization of Methyl Methacrylate onto Silk with Potassium Permanganate as Initiator

The graft copolymerization of methyl methacrylate onto silk fibers in aqueous solution with the use of manganese (IV) ions as initiator was investigated. The rate of grafting was determined by varying monomer, acidity of the medium, temperature, nature of silk, and the reaction medium. The graft yield increases significantly with increase of manganese (IV) concentration up to 15 meq/liter; with further increase of manganese (IV) concentration, the graft yield decreases. The effect of the increase of monomer concentration brings about a significant enhancement in the graft yield up to 7%, and with further increase of monomer concentration the graft yield decreases. The graft yield is considerably influenced by chemical modification prior to grafting. The effect of some inorganic salts and anionic surfactants on the rate of grafting has been investigated.     

Spectrophotometric Determination of Nitrogen Dioxide <Nitrite>

Abstract

A highly sensitive spectrophotometric method has been developed for the determination of nitrogen dioxide (nitrite as NO_z ^?) by reacting manganese dioxide in 1:20 perchloric acid. An amount of manganese dioxide (MnO_z) equivalent to the concentration of nitrogen dioxide becomes soluble due to the reduction of Mn (IV) to Mn (II) by nitrite in acidic medium. The soluble Mn (II) ion is filtered to remove excess of MnO₂ and is oxidized to permanganate ion by periodic acid in presence of phosphoric acid. The violet colored solution shows maximum absorbance at 525 nm. The sensitivity of the method is 0.08 ppm based on 0.0044 absorbance, and Beer's law is obeyed in the concentration range of 0.2 to 10.0 μg/mL of NO₂ ^?. Molar absorbance is found to be 2442 at 525 nm.

In the present investigation NO₂ ^? was treated with excess of MnO₂ in 1:20 perchloric acid where NO₂ ^? reduces equivalent amount of Mn (IV) to Mn (II) and becomes soluble. The soluble Mn (II) was heated to boiling and 25 mg (approx.) periodic acid is added and cooled. The volume of each solution is made to 50 mL in volumetric flask. Reagent blank is prepared in similar way except sodium nitrite solution. The absorbance is measured at 525 nm against reagent blank.     

Synthesis and Structural Investigations of [Mn(3)O(4)(phen)(4)(H(2)O)(2)](NO(3))(4).2.5H(2)O: A Water-Bound Complex Obtained by Cerium(IV) Oxidation

The trinuclear manganese complex [Mn(3)O(4)(phen)(4)(H(2)O)(2)](NO(3))(4).2.5H(2)O, 1 (where, phen = 1,10-phenanthroline), has been synthesized by the Ce(IV) oxidation of a concentrated solution of manganese(II) acetate and phen in 1.6 N nitric acid. The complex crystallizes in the triclinic space group P&onemacr; with a = 10.700(2) ?, b = 12.643(3) ?, c = 20.509(4) ?, alpha = 78.37(3) degrees, beta = 83.12(3) degrees, gamma = 82.50(3) degrees, and Z = 2. The structure was solved by direct methods and refined by least-squares techniques to the conventional R (R(w)) factors of 0.055 (0.076) based on 4609 unique reflections with F(o) >/= 6.0sigma(F(o)). The structure of the cation consists of an oxo-bridged Mn(3)O(4)(4+) core, with the geometry of the manganese atoms being octahedral. The coordination polyhedron of one of the manganese atoms (Mn(1)) consists of two &mgr; oxo ligands and two pairs of nitrogen atoms of two phen moieties, whereas that of each of the remaining two manganese atoms consists of three &mgr;-oxo ligands, two nitrogen atoms of a phen moiety, and the oxygen atom of a water molecule. The complex represents the second example for water coordination to manganese(IV) centers in complexes with a Mn(3)O(4)(4+) core. Optical spectra in ligand buffer (pH 4.5) reveal complete conversion of the complex into a Mn(III)Mn(IV) species. The observed room-temperature (298 K) magnetic moment of 3.75 &mgr;(B) indicates the presence of strong antiferromagnetic coupling in the complex.