Fluorimetrische Bestimmung geringer Mengen von Thioxanthenen durch Spaltung zu Thioxanthon bzw. dessen Derivaten

Zusammenfassung Psychopharmaka der Thioxanthen-Reihe können durch stark verdünnte Cer(IV)-sulfatlösung zu entsprechenden Thioxanthonen abgebaut werden. Diese sind fluorimetrisch bestimmbar. An Flupenthixol, Chlorprothixen, Prothixen, Clopenthixol und deren sek. Amino-Derivaten wird dieser Abbau gezeigt. Sulfoxide und Meprothixol sind dagegen nicht entsprechend abzubauen. Die Bestimmung von Flupenthixol und von 2-Chlorthioxanthon aus biologischem Material werden beschrieben. Da aus verschiedenen Psychopharmaka der Thioxanthen-Reihe sehr ähnliche und leicht zugängliche Abbauprodukte entstehen, ist diese Methode besonders leicht durchzuführen.

---

Fluorimetric determination of small amounts of thioxanthenes by degradation to thioxanthone and its derivatives, respectively

Psychotherapeutics of the Thioxanthene type are degraded to the analogous Thioxanthone derivates in very diluted Ce(SO₄)₂ solutions. These are determined by fluorescence spectrophotometry. In this way Flupenthixol, Chlorprothixen, Prothixen, Clopenthixol and their secondary amino-derivates are determined quantitatively. The corresponding sulphoxides and Meprothixol are not degraded by Ce(SO₄)₂ solution. Furthermore, the determination of Flupenthixol and 2-Chlorthioxanthone from biological material is described. The method is especially suitable because the different psychotherapeutics of the Thioxanthene type are degraded to the same kind of degradation product.

     

Structural and spectroscopic studies of nickel(II) complexes with a library of Bis(oxime)amine-containing ligands

A library of tripodal amine ligands with two oxime donor arms and a variable coordinating or noncoordinating third arm has been synthesized, including two chiral ligands based on l-phenylalanine. Their Ni(II) complexes have been synthesized and characterized by X-ray crystallography, UV-vis absorption, circular dichroism, and FTIR spectroscopy, mass spectrometry, and room-temperature magnetic susceptibility. At least one crystal structure is reported for all but one Ni/ligand combination. All show a six-coordinate pseudo-octahedral coordination geometry around the nickel center, with the bis(oxime)amine unit coordinating in a facial mode. Three distinct structure types are observed: (1) for tetradentate ligands, six-coordinate monomers are formed, with anions and/or solvent filling out the coordination sphere; (2) for tridentate ligands, six-coordinate monomers are formed with Ni(II)(NO(3))(2), with one monodentate and one bidentate nitrate filling the remaining coordination positions; (3) for tridentate ligands, six-coordinate, bis(mu-Cl) dimers are formed with Ni(II)Cl(2), with one terminal and two bridging chlorides filling the coordination sphere. The UV-vis absorption spectra of the complexes show that the value of 10 Dq varies according to the nature of the third arm of the ligand. The trend based on the third arm follows the order alkyl/aryl < amide < carboxylate < alcohol < pyridyl < oxime.     

Analytical methodology for the determination of aflatoxins in peanut butter: comparison of high-performance thin-layer chromatographic, enzyme-linked immunosorbent assay and high-performance liquid chromatographic methods

High-performance thin-layer chromatography (HPTLC) was applied to the separation and quantification of aflatoxin in 300 jars of "crunchy" peanut butter. A critical evaluation of the proposed HPTLC method has been carried out by statistical comparisons with a commercially available enzyme-linked immunosorbent assay (ELISA) kit and a high-performance liquid chromatographic (HPLC) method. The statistical tests indicated that whilst the distributions of the data sets obtained with each method were similar, the HPLC method was found to be biased. Over-all results indicated that the HPTLC method gave more consistent data, relatively lower standard deviations and lower coefficients of variation. The ELISA kit was found to be less precise than the HPTLC and HPLC methods and prone to some loss of sensitivity caused by matrix interference.     

An Optimal Algorithm to Find the Jump Number of Partially Ordered Sets

The jump number of a partially ordered set (poset) P isthe minimum number of incomparable adjacent pairs (jumps) in some linearextension of P. The problem of finding a linear extension of Pwith minimum number of jumps (jump number problem) is known to beNP-hard in general and, at the best of our knowledge, no exactalgorithm for general posets has been developed. In this paper, wegive examples of applications of this problem and propose for thegeneral case a new heuristic algorithm and an exactalgorithm. Performances of both algorithms are experimentallyevaluated on a set of randomly generated test problems.     

Suzuki-Miyaura cross-coupling of 3-pyridyl triflates with 1-alkenyl-2-pinacol boronates

Palladium-catalyzed Suzuki-type couplings of 3-pyridyl triflates with alkenyl pinacol boronates proceed in good to excellent yield. Optimized conditions use Pd(PPh(3))(4) (10 mol %) as catalyst with K(3)PO(4) (3 equiv) as base in dioxane.     

High Resolution LC-MS<Superscript>n</Superscript> Fragmentation Pattern of Palytoxin as Template to Gain New Insights into Ovatoxin-a Structure. The Key Role of Calcium in MS Behavior of Palytoxins

Palytoxin is a potent marine toxin and one of the most complex natural compounds ever described. A number of compounds identified as palytoxin congeners (e.g., ovatoxins, mascarenotoxins, ostreocins, etc.) have not been yet structurally elucidated due to lack of pure material in quantities sufficient to an NMR-based structural investigation. In this study, the complex fragmentation pattern of palytoxin in its positive high resolution liquid chromatography tandem mass spectra (HR LC-MSⁿ) was interpreted. Under the used conditions, the molecule underwent fragmentation at many sites of its backbone, and a large number of diagnostic fragment ions were identified. The natural product itself was used with no need for derivatization. Interestingly, most of the fragments contained calcium in their elemental formula. Evidence for palytoxin tendency to form adduct ions with calcium and other divalent cations in its mass spectra was obtained. Fragmentation pattern of palytoxin was used as template to gain detailed structural information on ovatoxin-a, the main toxin produced by Ostreopsis ovata, (observe correct font) a benthic dinoflagellate that currently represents the major harmful algal bloom threat in the Mediterranean area. Either the regions or the specific sites where ovatoxin-a and palytoxin structurally differ have been identified.