Photochemische Reaktionen. 121. Mitteilung. Zur Photochemie von ε,ζ-Methano-α,γ-dienonen und 7,8-Methano-1,3,5-trienen

Photochemistry of ε,ζ-Methano-α,γ-dienones and 7,8-Methano-1,3,5-trienes Irradiation of the δ-cyclopropyl-dienone (E)- 6 (λ ≥ 347 nm) gives (Z)- 6, 10 (1,5-sigmatropic H-shift), (E/Z)- 9 (electrocyclic process involving C(ε), C(ζ)-cleavage) and 11 (ring opening). The corresponding 6-cyclopropyl-triene (E)- 7 gives on singlet excitation (δ > 280 nm) 14 (1,5-sigmatropic H-shift) and, to a smaller extent, the bicyclo [3.2.0] heptenyl-dienes (E/Z)- 13 . However, on triplet excitation (λ ≥ 347 nm, benzophenone) (E)- 7 gives (E/Z)- 13 as the main products. On both ¹π,π*- and ³π,π*-excitation, (Z)- 7 and 15 are formed in small amounts.     

Photochemical reactions. 146th communication. Photochemistry of conjugated methano-epoxydienes: Participation of the neighboring cyclopropane ring in product formation via carbonyl ylide and carbene intermediates

On singlet excitation (λ = 254 nm, THF, pentane or hexane), the diastereoisomeric methano-epoxydienes (E)- 6 and (E)- 7 undergo interconversion and yield the products 8 – 11 . The main process is the cleavage of the oxirane ring to the vinyl carbene intermediate e which undergoes addition to the adjacent double bond furnishing the cyclopropene 8 . The alternative carbene intermediate f is evidenced by the formation of the cyclobutene 10 . For the fragmentation leading to 11 , the carbene f as well as the dipolar species h are considered as possible intermediates. On triplet sensitization (acetone, λ > 280 nm), (E)- 7 shows behavior typical of epoxydienes, undergoing fission of the C? O bond of the oxirane ring and isomerization to the compounds 13 , 14 and (E/Z)- 15 .     

Flow injection determination of hydrogen peroxide by means of a solid-state-peroxyoxalate chemiluminescence reactor

A solid-state reactor for detection of hydrogen peroxide in aqueous samples by peroxyoxalate chemiluminescence is described. Bis(2,4,6-trichlorophenyl)oxalate in solid form is packed into a bed reactor, which eliminates mixing problems and facilitates the instrumental development. Perylene is added as a sensitizer to a water/acetonitrile (20:80) carrier stream into which the samples (200–600 μl) are injected. Detection limits of 6 × 10^?9 M H₂O₂ (0.2 μg l^?1) are obtained with both a commercial and a home-made luminescence detector. Calibration graphs are linear up to 10^?5 M. The r.s.d. for 2 × 10^?7 M (6.7 μg^?1) hydrogen peroxide (n = 10) is 2.8%. Sample throughput is ca. 120 h^?1.     

Determination of oxidized, reduced and protein-bound glutathione in eye lenses by high-performance liquid chromatography and electrochemical detection.

A method for the detection of oxidized, reduced and protein-bound glutathione in eye lenses has been developed. Homogenized lens samples are deproteinated with acetonitrile and perchloric acid. Protein-bound glutathione is reduced by 1,4-dithiothreitol. Separation of the different forms of glutathione and dithiothreitol is performed by ion-pair reversed-phase high-performance liquid chromatography with sodium octylsulphate as the ion-pairing agent. The compounds are detected amperometrically using on-line-generated bromine, which oxidizes thiols and disulphides. In this way two samples can be analysed in triplicate in a single day. The lower detection limits are 80 and 48 nmol per gram wet lens for reduced and oxidized glutathione, respectively. The amounts of free reduced and protein-bound glutathione in calf lenses, determined with this method, are 6.8 +/- 0.4 and 0.96 +/- 0.03 mumol per gram wet lens, respectively. That of oxidized glutathione is less than 0.048 mumol per gram wet lens.     

Quantitative analysis of 3-indoleacetic acid and serotonin by in situ fluorescence on thin-layer chromatograms

Summary The characterization and quantitation of indoles by thin-layer chromatography followed by fluorometric scanning of the chromatographed species on the thin-layer provides a rapid and sensitive method of analysis at theg level and lower. Considerable increases in fluorescence intensity may be achieved if the plate is sprayed with a polar compound such as dimethylsulfoxide prior to measurement. The method may be used to quantitatively determine directly 50 ng samples of serotonin and indoleacetic acid and should be equally sensitive for other indolic compounds. The analysis of biological extracts for low levels of indoles should be a particular application for the method.

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Zusammenfassung Die Charakterisierung und Bestimmung von Indolen durch Dünnschicht-chromatographie und nachfolgende Fluoreszenzmessung der chromatographierten Substanzen auf der Dünnschichte erfordert eine rasche und empfindliche Analysenmethode für die Größenordnung von Mikrogramm und darunter. Eine erhebliche Verstärkung der Fluoreszenz läßt sich durch Sprühen mit einer polaren Verbindung wie z. B. Dimethylsulfoxid erreichen. Diese Bestimmungsmethode eignet sich für die direkte Bestimmung von 50 ng Serotonin und Indolessigsäure und dürfte auch für andere Indolderivate gleich empfindlich sein. Insbesondere Extrakte biologischen Materials dürften sich zur Analyse anbieten.

     

Fundamental systems of units in biquadratic parametric number fields

Let D, d be integers with D > 0, d dividing D and d square free and let α and β be the two roots of the quadratic equation x² ? Dx ?d = 0. Suppose (α ? β)² = D² + 4d > 1 and α² + β² = D² + 2d be square free. Introduce $\text{e =}\text{(ω + α)}\text{β}$ and $\text{u =}\text{(ω + β)}\text{α}$, where $\text{ω =}\text{a}{}^2\text{+ β}{}^2$. Then it is proved that e, u and θ form a fundamental system of units in the field $\text{Q}\text{D}{}^2\text{+ 4d}\text{,}\text{D}{}^2\text{+ 2d}$, where

$\text{θ=}\text{α}\text{β}\text{if}\text{d ≠ ± 1}\text{and}\text{(D,d) ≠ (5,?5)}$

$\text{θ=}\text{α}\text{β}\text{=}\text{1+}\text{5}\text{2}\text{if}\text{(D,d)=(5,?5)}$

$\text{θ=α}\text{if}\text{d = ± 1}\text{and}\text{(D,d) ≠ (3,?1)}$

$\text{θ=}\text{α=}\text{1+}\text{5}\text{2}\text{if}\text{(D,d)=(3,?1)}$

     

Determination of beta-19-nortestosterone and its metabolite alpha-19-nortestosterone in biological samples at the sub parts per billion level by high-performance liquid chromatography with on-line immunoaffinity sample pretreatment

An immunoaffinity precolumn (immuno precolumn) packed with Sepharose-immobilized polyclonal antibodies against the anabolic hormone 17 beta-19-nortestosterone (beta-19-NT) was used for the selective on-line pretreatment of raw extracts of urine, bile and tissue samples by high-performance liquid chromatography. Using UV detection (247 nm), beta-19-NT and its metabolite 17 alpha-19-nortestosterone (alpha-19-NT) can be determined in biological samples with a detection limit of 0.05 microgram/kg. Owing to the high clean-up efficiency of the immuno precolumn and the large sample volumes used, confirmation by gas chromatography-mass spectrometry is possible at this level. In urine samples from a calf treated with 19-nortestosterone 17 beta-laurate, the maximum concentrations of beta-19-NT (1.3 micrograms/l) and alpha-19-NT (3.1 micrograms/l) were found seven days after intramuscular administration. In a bile sample from this calf only alpha-19-NT (55 microgram/l) was detected. In meat samples from three treated calves, the concentration of beta-19-NT varied from 0.1 to 1.6 micrograms/kg and no alpha-19-NT could be detected. In liver samples from these calves, the concentrations of beta-19-NT and alpha-19-NT were less than 0.05-0.1 and 0.5-0.9 micrograms/kg, respectively. In the corresponding kidney samples, the concentrations of beta-19-NT and alpha-19-NT were 0.4-0.5 and 0.5-1.6 micrograms/kg, respectively. The application of the same immuno precolumn to the determination of 17 beta- and 17 alpha-trenbolone, two structurally related steroids, is also demonstrated.     

Trace-Level Determination of Phenol by Liquid Chromatography with On-Line Precolumn Technology and Fluorescence Detection

Abstract

A strongly basic anion-exchange resin is used for the trace enrichment and automated sample handling of phenol, with subsequent determination by reversed-phase liquid chromatography with fluorescence detection. Because of the presence of high concentrations of ionic compounds in the water samples tested, phenol is first trapped on a relatively long precolumn filled with a highly hydrophobic packing material; during this step, (in) organic anions which are not retained, are flushed to waste. In the next step, phenol is desorbed from this column at high pH and sorbed in a small zone (“peak compression”) on a short precolumn containing the anion exchanger.

In the analysis of tap and river water samples, the detection limit was found to be 10ppt (1:10¹¹).