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Strittmatter N.,Institute of Inorganic and Analytical Chemistry | Strittmatter N.,Imperial College London | During R.-A.,Institute of Soil Science and Soil Conservation | Takats Z.,Imperial College London
Analyst | Year: 2012

An analysis method for aqueous samples by the direct combination of C18/SCX mixed mode thin-film microextraction (TFME) and desorption electrospray ionization mass spectrometry (DESI-MS) was developed. Both techniques make analytical workflow simpler and faster, hence the combination of the two techniques enables considerably shorter analysis time compared to the traditional liquid chromatography mass spectrometry (LC-MS) approach. The method was characterized using carbamazepine and triclosan as typical examples for pharmaceuticals and personal care product (PPCP) components which draw increasing attention as wastewater-derived environmental contaminants. Both model compounds were successfully detected in real wastewater samples and their concentrations determined using external calibration with isotope labeled standards. Effects of temperature, agitation, sample volume, and exposure time were investigated in the case of spiked aqueous samples. Results were compared to those of parallel HPLC-MS determinations and good agreement was found through a three orders of magnitude wide concentration range. Serious matrix effects were observed in treated wastewater, but lower limits of detection were still found to be in the low ng L-1 range. Using an Orbitrap mass spectrometer, the technique was found to be ideal for screening purposes and led to the detection of various different PPCP components in wastewater treatment plant effluents, including beta-blockers, nonsteroidal anti-inflammatory drugs, and UV filters. © 2012 The Royal Society of Chemistry. Source

Stippich K.,Institute of Organic and Macromolecular Chemical | Kretschmer R.,Institute of Organic and Macromolecular Chemical | Beckert R.,Institute of Organic and Macromolecular Chemical | Goerls H.,Institute of Inorganic and Analytical Chemistry
Synthesis | Year: 2010

A new two-step synthesis of N,N-disubstituted 2,2-biimidazoles from bisimidoyl chlorides is reported. The bisimidoyl chlorides react smoothly with (2,2-dimethoxyethyl)amine to give bisamidines that are subsequently cyclized to give the corresponding biimidazoles. © Georg Thieme Verlag Stuttgart New York. Source

Schwalbe M.,Institute of Inorganic and Analytical Chemistry | Karnahl M.,Institute of Inorganic and Analytical Chemistry | Tschierlei S.,Institute of Physical Chemistry | Uhlemann U.,Institute of Physical Chemistry | And 9 more authors.
Dalton Transactions | Year: 2010

The complex [(dmcb)2Ru(dppz)](PF6)2 shows unexpected luminescence in water implying fundamentally different excited state relaxation pathways than are typically observed for complexes of this kind. © 2010 The Royal Society of Chemistry. Source

Heshe D.,University Childrens Hospital | Hoogestraat S.,University Childrens Hospital | Brauckmann C.,Institute of Inorganic and Analytical Chemistry | Karst U.,Institute of Inorganic and Analytical Chemistry | And 2 more authors.
Cancer Chemotherapy and Pharmacology | Year: 2011

Purpose: The observation that the orphan drug dichloroacetate (DCA) selectively promotes mitochondria-regulated apoptosis and inhibits tumour growth in preclinical models by shifting the glucose metabolism in cancer cells from anaerobic to aerobic glycolysis attracted not only scientists', clinicians' but also patients' interests and prompted us to further evaluate DCA effects against paediatric malignancies. Methods: The effects of DCA on mitochondrial membrane potential (ΔΨm), cell viability and induction of apoptosis were evaluated in paediatric tumour cell lines and the non-malignant cell line HEK293. In addition, combinations of DCA with the standard anticancer drugs cisplatin, doxorubicin, and temozolomide were tested and intra- and extra-cellular platinum species analysed. Results: DCA selectively induced phosphatidylserine externalisation and reduced ΔΨm in paediatric tumour cells compared to HEK293 cells, but DCA concentrations ≥10 mmol/L only moderately inhibited the growth of 18 paediatric tumour cell lines. DCA neither influenced the in vitro stability of cisplatin nor the cellular cisplatin uptake, but it abrogated the cytotoxicity of cisplatin in 7 out of 10 cell lines. DCA also affected the cytotoxicity of doxorubicin but did not influence the cytotoxicity of temozolomide. Despite phosphatidylserine externalisation, DCA failed to activate caspase 3/7 and, moreover, suppressed caspase 3/7 activation by cisplatin and doxorubicin. Conclusions: Our results indicate that apart from the intriguing effects of DCA on the glucose metabolism of cancer cells, the use of DCA for cancer treatment has to be evaluated carefully. Moreover, compassionate use of the orally available drug by patients with cancer themselves without medical supervision is strongly discouraged at present. © 2010 Springer-Verlag. Source

Behrends F.,Institute of Physical Chemistry | Wagner H.,Organic Chemistry Institute | Studer A.,Organic Chemistry Institute | Niehaus O.,Institute of Inorganic and Analytical Chemistry | And 2 more authors.
Macromolecules | Year: 2013

A novel synthetic route toward poly(4-methacryloyloxy-2,2,6,6- tetramethylpiperidine-N-oxyl) (PTMA) is described. The polymerization of alkoxyamine-based monomers by atom transfer radical polymerization (ATRP) was investigated, as the polyalkoxyamine serves as the precursor for PTMA. The polydispersity indices (PDIs) and the kinetic data of the polymerization indicate a controlled reaction. The oxidative C-O bond cleavages of the polyalkoxyamine lead to PTMA. This transformation occurs with excellent yields, and it is possible to transfer the narrow PDIs of the prepolymer to PTMA. The material is characterized in detail using cyclic voltammetry in solution and magnetic susceptibility measurements as well as multinuclear solid state NMR and EPR spectroscopies. The conversion of the precursor polymer to the polynitroxide can be conveniently monitored by 1H and 19F magic-angle spinning (MAS) as well as 13C{1H} cross-polarization (CP)-MAS NMR. In addition, the intermolecular interaction of the nitroxide side chain units in the polymer at high conversion can be detected and monitored by the observation of pronounced low-frequency shifts. © 2013 American Chemical Society. Source

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