Beiträge zur Koordinationschemie von Rhenium(III)chlorid in nichtwäßrigen Lösungen

Coordination reactions of solutions of Re₃Cl₉ in acetonitrile, propanediol-1,2-carbonate, acetone and dimethylsulfoxide yield compounds with unchanged metal-cluster structures. The following compounds were isolated and characterised: [Et ₄N]₃[Re₃Cl₉(N₃)₃], [Et ₄N]₃[Re₃Cl₆(N₃)₆], [Et ₄N]₃[Re₃Cl₃(N₃)₉], [Et ₄N]₃[Re₃Cl₉(CN)₃], [Et ₄N]₃[Re₃Cl₃(CN)₉],Et ₄N]₃[Re₃Cl₉(NCS)₃], [Et ₄N]₃[Re₃Cl₆(NCS)₆], [Et ₄N]₃[Re₃Cl₃(NCS)₉], Re₃Cl₉·(DMSO)₃, Re₃Cl₉·(HMPT)₃.     

Comparative analytical quantitation of clenbuterol in biological matrices using GC-MS and EIA

A simple and sensitive procedure utilizing GC-MS for the identification and quantitation of clenbuterol in biofluids and tissues is described. This improved method utilizes trimethylboroxine for the derivatization of clenbuterol, requires only 1 mL/g of biological sample, and most importantly does not require an extra cleaning step for urine specimens prior to extraction. Linear quantitative response curves have been generated for derivatized clenbuterol over a concentration range of 5-200 ng/mL. The extraction efficiency at four representative points of the standard curve exceeded 90% in both specimen types (plasma and urine). Linear regression analyses of the standard curve in both specimen types exhibited correlation coefficients ranging from 0.997 to 1.000. The Limit of detection (LOD) and Limit of quantitation (LOQ) values for plasma specimens were determined to be 0.5 and 1.5 ng/mL respectively. For urine specimens, LOD and LOQ values were 0.2 and 0.7 ng/microL respectively. Percentage recoveries ranged from 91 to 95% for urine and 89 to 101% for plasma. Precision and accuracy (within-run and between-run) studies reflected a high level of reliability and reproducibility of the method. In addition to its reliability, sensitivity and simplicity, this modified procedure is more efficient and cost effective, requiring less time, only 1 mL of sample, and minimal amounts of extraction solvents. The applicability of the method for the detection and quantitation of clenbuterol in biological tissues of rats treated with the drug was demonstrated successfully. For comparative analysis of clenbuterol in plasma and liver samples, both GC-MS and enzyme immunoassay (EIA) methods are found to be suitable. Due to potential antibody-cross reactivity with EIA, the GC-MS method is the method of choice for most samples because of its specificity. However, the EIA method is considered the method of choice for analysis of clenbuterol found in concentrations below the limits of quantitation by GC-MS due to its sensitivity.     

Synthese von oligosaccharid-determinanten des T-antigens mit amid-spacer zur darstellung synthetischer antigene

The β (1 → 3) -linked disaccharide $\text{1}$$\text{5}$ was synthesized from $\text{D}$-galactose and a $\text{D}$-galactosamine unit with a watersoluble amide spacer. This represents the hapten of T-antigen and, when coupled to a protein, is suitable for use as an artificial antigen. Other O-β-$\text{D}$-galactosylated derivatives of galactosamine were synthesized.     

Ion-pair mediated transport of small model peptides in liquid phase micro extraction under acidic conditions

This paper discusses the behaviour of five small model peptides in a three phase (aqueous donor-organic-aqueous acceptor) liquid phase micro extraction system in relation to their physico-chemical properties (charge, hydrophobicity). It is proved that for all peptides transport over the organic phase is mediated by aliphatic sulphonic acids. Heptane-1-sulphonic acid gave the best overall recoveries. It appeared that peptides with hydrophobic properties (IPI) and a high number of positive charges (KYK) show good recoveries and are enriched in the acceptor phase. Variation in the pH (1.6-4.4) of the donor phase shows that there are peptide-dependent optimal pH-values for their recovery. Increasing pH in the acceptor phase shows that in most cases the recovery decreases due to decreased ion-pair mediated membrane transport. For KYK the partition between the organic phase and the aqueous acceptor-phase is also driven by the solubility in the aqueous acceptor phase. Increase of the ion strength of the acceptor phase did not affect the recovery of the peptides. Except for KYK, which showed decreased recovery when the ion strength increased. Another finding is that delocalisation of positive charge causes bad recovery, probably due to incomplete ion-pair-peptide complex formation.     

Efficient synthesis of enantiopure conduritols by ring-closing metathesis.

Two short synthetic approaches to enantiopure conduritols are described starting from the chiral pool. In both cases, the cyclohexene ring is assembled via ring-closing olefin metathesis. The terminal diene precursers for the metathesis reaction are prepared either from octitols or from tartaric acids. The former route involves a new method for selective bromination of the primary positions in long-chain carbohydrate polyols. Subsequent reductive elimination with zinc then generates the diene. The latter route uses a highly diastereoselective addition of divinylzinc to tartaric dialdehydes for preparation of the dienes.     

带斜拉索的索结构的特征频率分析

计算了带斜拉索的索结构在面内振动的近似特征频率，该索结构的不同位置还带有质点．发现经典传递矩阵法已不足以解决此问题，因此采用较大的外矩阵来确定特征频率方程．然后在对外矩阵渐近估计的基础上，确定一般索结构的动力学性能．