Thiolactame als Reagenzien in der quantitativen Analyse. IX

Zusammenfassung Thiocaprolactam (T) eignet sich zur Goldbestimmung im Konzentrationsbereich 10 bis 130 g Au/ml mit einem Fehler von ±0,5g. Thiocaprolactam bildet mit [AuCl₄]^– eine Verbindung im molaren Verhältnis TAuCl=112, mit [AuJ₄]^– im molaren Verhältnis TAuJ=213. Dagegen bilden sich im System T:Au:Br zwei verschiedene Verbindungen: Ein Bromidkomplex mit höherem Goldgehalt TAu=12, der mit Chloroform extrahierbar ist, und eine sich als Niederschlag ausscheidende Verbindung mit dem Verhältnis TAuBr=112.

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Thiolactams as reagents in quantitative analysis. IX

Summary Thiocaprolactam (T) is suitable for the determination of gold in the concentration range 10–130g Au/ml with an error of ±0.5g. Thiocaprolactam yields with [AuCl₄]^– a compound in the molar ratio TAuCl=112, with [Aul₄]^– in the molar ratio TAuI=213. On the other hand various compounds result in the system TAu Br. The molar ratio in the case of the bromide complex has a higher gold content, namely TAu=12; this product is extractable with chloroform and a compound that comes down as a precipitate shows the ratioT Au Br=112.

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Herrn Dr.K. Czerepko möchte ich hiermit meinen Dank für die Diskussion der Ergebnisse aussprechen.     

Studies on plutonium(IV) hydroxosuccinate

The precipitation behaviour of basic plutonium(IV) compounds from dilute nitric acid medium with aliphatic dicarboxylic acids has been investigated. Unlike plutonium(IV) oxalate, which is precipitated in acid medium (1–4M), the higher dicarboxylates precipitate in 0.9–2.5 pH range and their elemental analysis indicate Pu/dicarboxylate ratio of 11. The mode of formation, composition, solubility and thermal degradation behaviour for plutonium(IV) hydroxosuccinate has been studied. The hydroxy group determination by kinetic titration using fluoride complexing revealed that the compound has a Pu:OH ratio of 11 and determination of bridging oxygen group gave a Pu:O ratio of 10.5 suggest its formation as hydroxysuccinate having an oxobridged formula.     

A sensitive and highly selective extractive spectrophotometric method for the determination of palladium

Summary A Sensitive and Highly Selective Extractive Spectrophotometric Method for the Determination of Palladium Palladium forms an anionic chelate with 4-(2-pyridylazo)resorcinol (PAR, H₂R) which is extractable with xylometazolonium cation (XMH) into chloroform in the pH range 7.2–7.8 giving an intensely pinkish red coloured solution. The coloured species exhibits maximum absorbance at 520 nm with molar absorptivity 3.34×10⁴1·mole^–1·cm^–1 and obeys Beer's law in the range 0.8–5.30g/ml of palladium. The composition of the extracting species is found to be 111 for Pd(II)PARXMH. Large concentrations of EDTA and oxalate have no interference in the spectrophotometric determination of palladium by this procedure. Based on this a highly selective and sensitive method for the determination of palladium in the presence of Zn(II), Cd(II), Hg(II), Fe(III), Mn(II), Co(III), Mo(VI), Ru(IV), Sb(III), Al(III) is described. The application of this method for the determination of palladium in synthetic mixtures corresponding to the composition of jewel alloy and stibiopalladinite mineral is also demonstrated.     

Micro reversed phase liquid chromatography of Cd-, Ni-, Zn-, Cu-, Co-, Hg-diethyldithiocarbamates at picogram level

Summary The use of micro reversed phase columns (Polygosil C18) for the separation of metal DDTC chelates was investigated and applied to drinking water analysis.Three different eluents have been tested [702010 (MeOH H₂OCHCl₃); 8020 (MeOHH₂O); 7030 (MeOHH₂O)] at flow rates of 7 to 28gml/min. Eluent composition showed strong influence onk of Co(DDTC)₂.The linear working curves fitted at least 3 decades with detection limit of 40–500 pg. Monitoring at _max instead of 254 nm decreases the detection limits. The consume of eluent is 10 to 20 times less than with analytical columnes.Results of micro LC have been compared with predictible data of theoretical considerations.

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Mikro-Umkehrphasen-Flüssigkeitschromatographie der Cd-, Ni-, Zn-, Cu-, Co-, Hg-Diethyldithiocarbamatchelate im Picogrammbereich

Zusammenfassung Die Anwendung von Mikro-RP-Säulen (Polygosil C18) für die Trennung von Metall-DDTC-Chelaten wurde untersucht und auf die Analyse von Trinkwasser angewendet. Drei verschiedene Eluentien [702010 (MeOH H₂OCHCl₃); 8020 (MeOHH₃O); 7030 (MeOHH₂O)] bei Fließraten von 7 bis 28gml/min wurden untersucht,k von Co(DDTC)₂ wird von der Eluenszusammensetzung erheblich beeinflußt. Der lineare Meßbereich betrug mindestens 3 Dekaden mit einer Nachweisgrenze von 40–500 pg, die durch Detektion bei _max statt bei 254 nm noch weiter gesenkt werden kann.Der Verbrauch an Eluens ist 10–20mal geringer als bei analytischen Säulen.Die Ergebnisse der Mikro-LC wurden anhand theoretischer Überlegungen mit den vorhersagbaren Daten verglichen.

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Presented in parts at 9th International Symposium on Microchemical Techniques, Amsterdam 1983.     

Behaviour of transplutonium and rare earth elements on TVEX

Behaviour of transplutonium and rare-earth elements on TVEX, containing TBP, HDEHP, mixture of TBPHDEHP (11), PAPNA and TOA has been studied. The analytical possibility of isolation and separation of tetravalent Pu and Bk from trivalent actinides and lanthanides from strong nitric acid solutions (1.0–12.0) on TVEX with TBP, POR, HDEHP and TOA has been demonstrated. The separation of trivalent Bk, Cf and Eu from Am and Cm is real on TVEX, containing HDEHP and mixture of TBPHDEHP.     

Analytical applications of mixed-ligand complexes

Summary In medium of pH=1, vanadium(V) forms a 1 1 cationic complex with PAR, the instability constant of the complex beingpK=5.6. In the presence of hydrogen peroxide a 111 mixed-complex develops which is uncharged. The molar absorptivity of the complex ( ₅₄₀=1.28×10⁴ l·mole^–1·cm^–1) provides a possibility for the spectrophotometric determination of 1–65M hydrogen peroxide.

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Zusammenfassung In saurer Lösung (pH=1) bildet Vanadin(V) mit PAR einen positiv geladenen Komplex, dessen Komplexkonstante dem pK-Wert 5,6 entspricht. In Anwesenheit von Wasserstoffperoxid bildet sich mit diesem Kation ein ungeladener Mischkomplex im Verhältnis 111. Dessen Extinktionskoef-fizient ( ₅₄₀=1,28×10⁴ l · mol^–1 · cm^–1) ermöglicht die spektrophotometrische Bestimmung von Wasserstoffperoxid im Konzentrationsbereich von 1–65Mol/l.

     

An lonophoretic study of the interactions between metal lons and 1-phenyl-3-pyrazolidinone

Summary The ionic behaviour of 1-phenyl-3-pyrazolidinone (phenidone) at different pH values and its complexes with a selected group of metal ions such as Mg(II), Al(III), Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) were investigated in the pH range of 1–13 by paper electrophoresis. pH-mobility curves were determined for phenidone, the nine metal ions and 21 metal-ligand systems with 1, 110 and 1100 metal: ligand ratios. The effect of the pH on complex formation and the influence of the phenidone concentration on the metal ion mobilities are discussed.Presented at the XXII International Conference on Coordination Chemistry, August 23–27, 1982, Budapest (Hungary).     

Some effective solvents for rapid and reliable characterization of phenylthiohydantoin-amino acids

Summary One-dimensional chromatography with internal standards permits reliable identification of the phenylthiohydantoins from all the common amino acids with the following TLC systems: silica gel — chloroform/n-butyl acetate (9010), di-isopropylether/ethanol (955), dichloromethane/ethanol/acetic acid (9082) ortrans-dichloroethylene/ethanol/acetic acid (88102); and cellulose with 25% formic acid — heptane/isobutanol/75% fromic acid (40309) or silica gel — chloroform/ ethanol/acetic acid/water (50470.52.5).Abbreviations: PTH=phenylthiohydantoin, TLC=thin-layer chromatography, HPTLC=high-performance TLC; other abbreviations: see end of text. Proportions in solvent mixtures are v/v except where otherwise indicated.     

Measurement of mercaptans in gasoline

In an r-FIA single-line manifold, 10-l portions of 5,5-dithiobis (2-nitrobenzoic acid) and 2% (v/v) ethylenediamine in 80 20 inethanol: acetone are injected from pressurized containers via high-speed on/off valves into a flowing gasoline stream. The reaction product, 2-nitro-5-mercaptobenzoate, is detected optically at 412 nm after a reaction time of 15s. The system is intended for the measurement of mercaptans in the 0–2 mM (0–64 ppm S) concentration range. The response for C1–C10n-mercaptans ranges from 0.766–0.159 mAU/mM, the response to C1–C5n-mercaptans is 630 mAU/mM (±18.5% RSD). The response ratio of C1 and C5 mercaptans is 1 0.653. The system permits extreme conservation of reagents; only 10 l of each reagent is consumed per determination.     

Oxidation of organic compounds

It has been established that the main products of the oxidative ammonolysis of tris(hydroxymethyl)-4-picoline are isonicotinic acid and its amide and nitrile. At a molar ratio of the starting material to oxygen (in the form of air) to ammonia to water to 1 80–90 12–30 125–150 and with a contact time of 0.12–0.20 sec, these compounds can be obtained with yields of, respectively, 25–30, 5–10, and 45–50% of those theoretically possible on the basis of the raw material fed.For part LIII, see [1].     

Detection and determination of benzophenone present in diphenylhydantoin sodium formulations and drug substance

Summary The detection of benzophenone in sodium diphenylhydantoin formulations and drug substance is carried out by thin-layer chromatography on silica gel 60 F using toluene/methanol/ethyl acetate/acetic acid/chloroform (802015105) or ethyl acetate/methanol/ammonium hydroxide (85105) as solvent and UV-light for visualizing. The determination is performed by measuring the absorption at 248 nm. The method is recommended for production monitoring.

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Nachweis und Bestimmung von Benzophenon in Natriumdiphenylhydantoin-Formulierungen und -Reinsubstanz

Zusammenfassung Der Nachweis erfolgt dünnschicht-chromatographisch auf Silicagel 60 F mit Toluol/Methanol/Äthylacetat/Essigsäure/Chloroform (802015105) oder Äthylacetat/Methanol/Ammoniak (85105) als Lösungsmittel und durch Sichtbarmachung mit UV-Licht. Die Bestimmung wird durch Absorptionsmessung bei 248 nm vorgenommen. Das Verfahren wird zur Produktionskontrolle empfohlen.

     

Quantitative electron-probe microanalysis of light elements: Determination ofa-Si∶C∶N∶O∶H insulating films

Amorphous SiCNOH films (1–3 m) are studied by EPMA after deposition of gold (1–5 nm) as a conductive coating. Its influence on thek-ratios (X-ray intensity relative to an uncoated standard) of silicon, carbon, nitrogen and oxygen is described as a linear function of the simultaneously determinedk-ratio of gold. Thek-ratios representing the uncoated specimen are obtained by extrapolation and, in combination with the PAP matrix correction model, quantitative EPMA can be performed with an analytical error of 2–5%, as it is demonstrated by samples of SiC, Si₃N₄ and SiO₂. No systematic shift of the concentrations is observed for layers ofa-SiCNOH determined at various electron energies of 5–12.5 keV. Hydrogen is calculated by difference and the concentrations prove to be a useful estimate in agreement with the results of chemical analysis. Si-K/Si-K spectra recorded on organo-silicon films and binary silicon compounds point out significant differences concerning the formation of Si-C, Si-N and Si-O chemical bonds.     

Thermodynamic analysis of the interaction of proflavin with the deoxytetraribonucleotide 5′-d(GpCpGpC) according to proton magnetic resonance data

The temperature dependences of the chemical shifts of the proflavin protons in a mixture with the deoxytetraribonucleoside diphosphate 5-d(GpCpGpC) in aqueous solution were investigated on a pulse NMR spectrometer (500 MHz). A procedure is proposed for calculating the mole fractions of various associates in solution as a function of the temperature. The Gibbs free energies, enthalpies, and entropies of the reactions forming the 11, 12, 21, and 22 complexes of proflavin with the tetranucleotide were determined. The results are evidence of a vital role of hydrophobic interactions in the formation of complexes of the dye with the duplex of the tetramer.Translated from Teoreticheskaya i Éksperimental' naya Khimiya, Vol. 28, Nos. 5–6, pp. 430–435, September–December, 1992.     

Solvent extraction and spectrophotometric including graphite furnace atomic absorption determination of molybdenum in the environment

A selective and sensitive method for the extraction and microgram determination of molybdenum (VI) with hydroxamic acid as yellow molybdenum-hydroxamate complex from acidic medium is described. The molybdenum-PCPPSAHA complex has _max 388 nm, molar absorptivity 5.0 × 10³l mol^–1 cm^–1. The system obeys Beer's law in the range of 1–28 g/ml of molybdenum(VI). Sandell's sensitivity is 0.0192 g cm² and stoichiometry of the complex is 12, molybdenum: PCPPSAHA while mixed complex molybdenum-PCPPSAHA-morin has _max 400 nm and molar absorptivity 5.9 × 10³lmo1^–1 cm^–1 and stoichiometry of the complex is 121.The molybdenum is determined by graphite furnace atomic absorption spectrophotometry after directly pipetted the extract into the furnace which increases the sensitivity 20 fold.     

Spectrophotometric determination of thorium as molybdothoric acid with basic dyes

Color developments based on the ion-association complexes of molybdothoric acid with three basic dyes (BD), rhodamine B(RB), butylrhodamine B(BRB) and nile blue (NB), were investigated in aqueous acidic solution in the presence of poly(vinyl alcohol) (PVA). Their spectrophotometric behavior, such as the conditions suitable for the reactions and the effects of foreign ions, were thoroughly studied. The ThMoBD ratio in the complexes was found to be 1123. Their absorption maxima were at 570, 570 and 590 nm with apparent molar absorptivities of 3.50 × 10^–6, 3.63 × 10⁶ and 4.45 × 10⁶ dm³ mol^–1 cm^–1, respectively. Beer's law was obeyed up to 0.8, 0.8 and 0.7 g thorium per 25 ml, respectively. The detection limits (3) were 1.1, 1.8 and 3.4 ng ml^–1, respectively, and for 0.02 ug ml^–1 solution of thorium the relative standard deviations were 3.0, 2.9 and 1.5%, respectively (n = 11). The proposed methods were applied to the determination of trace amounts of thorium in some geological samples.     

Extraction-spectrophotometric determination of iron with 2-(2′-benzothiazolylazo)-4,6-dimethylphenol

An extraction-spectrophotometric method for the determination of trace amounts of iron based on its extraction into chloroform with 2-(2-benzothiazolylazo)-4,6-dimethylphenol (BTADMP) from a pH 6.5 medium has been developed. The extracted 12 FeBTADMP complex species allow the determination of 4–30gmg of iron (=3.92×10⁴1·mol^–1·cm^–1 at 790 nm). The method is highly selective and has been applied to the determination of iron in polymineral-polyvitamin pharmaceutical products.     

Characterization of modified alumina as adsorbents. Modification of alumina with alkali metal phosphates

Summary Alumina may be considerably modified by impregnating at 100°C in the alkali metal phosphate solution. The available solution for modification was the KOH–K₂HPO₄–AlPO₄ (11.51M) solution or the NaOH–Na₂ HPO₄ (0.81.1 M or 11.5M) solution. The appreciable improvement on chromatograms was obtained by preheating of the alumina, especially above 800°C prior to impregnating A further modification may be made by ignition of the alumina impregnated. The x-ray diffraction studies revealed the phase transformation of the alumina inducing the modification, and the essential factor of the present modification method being the thermal treatment of the alumina at temperatures forming -alumina.     

Effect of electrolyte type on the electrokinetic behavior of sulfonated polystyrene model colloids

Sulfonated polystyrene latex particles were prepared by a two-stage shot-growth emulsion polymerization process in the absence of emulsifier. Sodium styrene sulfonate (NaSS) was used as an ionic co-monomer to produce a series of latex particles with the same particle size but with different surface charge densities. The electrophoretic mobility of this functionalized model colloid was studied in the presence of various types of inorganic electrolytes. The _e curves of these latexes exhibit a pronounced maximum at high electrolyte concentrations: 5·10^–2 M for 11 electrolytes and 10^–2 M for 21 and 12 electrolytes. When a 31 electrolyte (LaCl₃) was used, the electrophoretic mobility changed to positive values at high concentration due to the specific adsorption of lanthanum species. The experimental results for the electrokinetic characterization of these sulfonated polystyrene model colloids suggest that the surface of the particles is covered by a layer of oligomers or polymer chains which shift the shear plane toward the bulk solution, increasing the anomalous surface conductance of the polystyrene microsphere-electrolyte solution interface.