μSr studies of free radicals in the gas phase

Muonium (Mu=₊+e^-) is the bound state of a positive muon and an electron. Since the positive muon has a mass about 1/9 of the proton, Mu can be regarded as an ultra light isotope of hydrogen with unusually large mass ratios (MuHDT=1/9123). The muon spin rotation technique (SR) relies on the facts that (1) the muon produced in pion decay, ^{+ +} + , is 100% spin polarized and (2) the positron from muon decay is emitted preferentially along the instantaneous muon spin direction at the time of the muon decay.In transverse field SR (TF-SR), the precession of the muon spin in muonium substituted radicals is directly observed by detecting decay positrons time differentially. From observed radical frequencies, the hyperfine coupling constants (A ) of C₂H₄Mu, C₂D₄Mu,¹³C₂H₄Mu, C₂F₄Mu, and C₂H₃FMu are determined. In the longitudinal field avoided level crossing (LF-ALC) technique, one observes the resonant loss of the muon spin polarization caused by the crossing of hyperfine levels at particular magnetic fields. The LF-ALC method together with the information onA obtained from TF-SR allows one to determine the magnitude and sign of the nuclear hyperfine constants at - and -positions. Results are compared with hydrogen substituted ethyl-radicals and isotope effects are discussed.     

Untersuchungen zur mikroanalytischen Bestimmung der langkettigen Fetts?uren im Blut

Zusammenfassung Für die im Plasma an Albumin gebundenen sog. freien Fettsäuren (FFS) wird ein neues gas-chromatographisches Analysenverfahren vorgestellt. Das Probenvolumen beträgt 50 l Serum oder Plasma. Die Extraktion erfolgt in 1,1 ml CHCl₃/CH₃OH (21, v/v) mit n-Heptadecansäure als innerem Standard (0,05 Val C₁₇₀/ml). Nach Eindampfen am Rotationsverdampfer werden die FFS im verschlossenen Reaktionskölbchen mit 20 l CH₃J/Essigsäureäthylester (11, v/v) über festem K₂CO₃ bei 90°C 1 h verestert. Die Varianz des Verfahrens errechnet sich bei 15 Parallelbestimmungen zu 4,85%.Vortrag anläßlich der Tagung Spurenanalyse, 2. bis 5. April 1973 in Erlangen.     

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.     

Spin-crossover complexes in solution. III. Substituent- and solvent effects on the spin-equilibrium of 4-substituted iron(II)-2,6-bis-(benzimidazol-2′-yl)-pyridine systems

Summary Transition metal complexes of the composition [Fe(4-X-bzimpy)₂](ClO₄)₂ [bzimpy = 2,6-bis-(benzimidazol-2-yl)pyridine and X=H, OH, Cl] show thermally accessible spin-crossover behaviour in solution that depends on both the ligand and the solvent.¹H-NMR spectroscopy and UV-visible spectroscopy measurements suggest that ligand substituent effects, solvent donor-acceptor properties and hydrogen-bonding may be employed to fine-tune the ligand field strength and hence to affect the spin-crossover behaviour. The ligand substitution changes in solution are reflected by the magnetic data (X=H:_exp=2.50 _B; X=OH:_exp=4.20 _B and X=Cl:_exp=4.30 _B at 294 K in MeOH), and by the shift of metal-to-ligandcharge-transfer band (X=H, =557 nm; X=OH, =520 nm; X=Cl, =500 nm). [Fe(bzimpy)₂](ClO₄)₂ exhibits a pronounced spin-crossover equilibrium (¹A₁ ⁵T₂) in solution (K _sc=0.26 at 293 K; _exp=1.30 3.40 _B for 213 328 K in MeOH). A small variation of magnetic moments of [Fe(4-OH-bzimpy)₂](ClO₄)₂ (_exp=3.77 4.73 _B at 220 332 K) might indicate either the existence of (temperature dependent) hydrogen bonding between the ligand and solvent molecules or a temperature dependent variation in the population of the⁵E_g sublevel. The presence of strong donor solvents (DN 30) shifts the spin-state of the complexes.In course of absence from the Chemistry Department, Jahangirnagar University, Dhaka, Bangladesh     

Polarographische Bestimmung von Diazepam in Leichenblut ohne vorherige Extraktion

Zusammenfassung Eine polarographische Methode zur direkten Bestimmung von Diazepam in Leichenblut ohne vorherige Extraktion wird beschrieben. Als Grundelektrolyt wird Britton-Robinson-Puffer (pH 2,8) und Methanol (41v/v) empfohlen. Die untere Bestimmungsgrenze liegt bei 20 g Diazepam/ml Blut.

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Polarographic determination of diazepam in cadaver blood without prior extraction

Summary A polarographic method is described for the direct determination of diazepam in cadaver blood without previous extraction. The fundamental electrolyte recommended is Britton-Robinson buffer solution (pH=2.8) and methanol (41v/v). The lower determination limit is situated at 20g diazepam/ml blood.

     

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.

     

Komplexe des Kobalts mit o-Methylbenzamidoxim

Zusammenfassung Die stufenweise Komplexbildung des Co²⁺ mit o-Methylbenzamidoxim (oMB) gibt in alkalischer Lösung zwei Komplexe, deren Zusammensetzung 11 und 12 ist. Die Bildungskonstanten wurden nach graphisch-logarithmischen Methoden bestimmt. Die Bildungskonstanten sind ₁=(4,1±0,6)·10⁴ und ₂ = 0,41 bei 25° C und Ionenstärke =1.

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Co(II) complexes of o-methylbenzamidoxime

In alkaline solution 11 and 12 complexes are formed stepwise from Co²⁺ and o-methylbenzamidoxime. The ligand numbers and the formation constants were determined from spectrophotometric data by logarithmic graphical methods. The formation constants are ₁=(4,1±0,6)·10⁴ and ₂ = 0,41 at 25° C and =1.

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Mit 3 Abbildungen     

Thermodesorption of mixtures. Hydrocarbon, hydrogen sulfide and oxygen from the surface of molybdenum sulfide

The presence of hydrogen sulfide and oxygen in mixtures increases the number of sites for dissociative desorption on the surface of MoS₂ as compared with the adsorption of individual hydrocarbons. This phenomenon can be explained by a change in the coordination state of the active sites (molybdenum ions) upon the adsorption of the gases mentioned.

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, MoS₂ . .

     

Dehydroxylation and catalytic activity of dealuminated Y zeolites

Dehydroxylation and catalytic conversion of m-xylene over dealuminated zeolites were studied.

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- .