TY - JOUR A1 - Schwarz, G. A1 - Beck, S. A1 - Weller, Michael G. A1 - Linscheid, M.W. T1 - Comparison of the fragmentation behavior of differentially metal-coded affinity tag (MeCAT)-labeled peptides PY - 2012 DO - https://doi.org/10.1002/jms.3036 SN - 1076-5174 SN - 1096-9888 VL - 47 IS - 7 SP - 885 EP - 889 PB - Wiley CY - Chichester AN - OPUS4-27436 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H.R. A1 - Böhme, S. A1 - Schwarz, G. A1 - Krüger, Ralph-Peter A1 - Schulz, Günter T1 - Macrocycles 18. The Role of Cyclization in Syntheses of Poly(ether-sulfone)s N2 - Poly(ether-sulfone)s having an identical backbone were prepared by four different methods. First, silylated bisphenol A (BSBA) was polycondensed with 4,4'-difluorodiphenyl sulfone (DFDPS) and K2CO3 in N-methylpyrrolidone with variation of the temperature. Second, analogous polycondensation were conducted using CsF as catalyst (and no K2CO3). Third, CsF-catalyzed polycondensations BSBA and DFDPS were conducted in bulk up to 290 C. Fourth, free bisphenol was polycondensed with DFDPS or 4,4'-dichlorodiphenyl sulfone and K2CO3 in DMSO with azeotropic removal of water. MALDI-TOF mass spectroscopy revealed that the first method mainly yielded cyclic poly(ether-sulfone)s which were detected up to masses around 13 000 Da. These and other results suggest that these polycondensations take a kinetically kontrolled course at tempeatures 145 C. This interpretation is also valid for the fourth method where high yields of cycles were obtained with DFDPS. With the less reactive 4,4'-dichlorodiphenyl sulfone lower conversions, lower molecular weights and lower fractions of cycles were found. In contrast to KF (resulting from K2CO3) CsF cleaves the poly(ether sulfone) backbone at temperatures > 145 C. Smaller amounts of smaller cycles were found in these CsF-catalyzed polycondensations which were in this case the result of thermodynamically controlled "back-biting degradation". PY - 2001 DO - https://doi.org/10.1021/ma010218l SN - 0024-9297 SN - 1520-5835 VL - 34 SP - 8886 EP - 8893 PB - American Chemical Society CY - Washington, DC AN - OPUS4-2176 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H.R. A1 - Rabenstein, M. A1 - Langanke, D. A1 - Schwarz, G. A1 - Schmidt, M. A1 - Maskos, M. A1 - Krüger, Ralph-Peter T1 - Ring-closing polycondensations N2 - The role of cyclization in polycondensations is discussed for two different scenarios: thermodynamically-controlled polycondensation (TCPs) on the one hand and kinetically-controlled polycondensations (KCPs) on the other. The classical Carothers–Flory theory of step-growth polymerization does not include cyclization reactions. However, TCPs involve the formation of cycles via ‘back-biting degradation’, and when the ring–chain equilibrium is on the side of the cycles the main reaction products of the TCP will be cyclic oligomers. Two groups of examples are discussed: polycondensations of salicyclic acid derivatives (e.g. aspirin) and polycondensations of dibutyltin derivatives with long {alpha}-, {omega}-diols or dicarboxylic acids. Furthermore, various kinetically-controlled syntheses of polyesters and polyamides were studied and carefully optimized in the direction of high molecular weights. High fractions of cyclic oligomers and polymers were found by MALDI-TOF mass spectrometry, and their fractions increased with optimization of the process for molecular weight. These results disagree with the Carothers–Flory theory but agree with the theoretical background of the Ruggli–Ziegler dilution method (RZDM). When poly(ether-sulfone)s were prepared from 4,4'-difluorodiphenylsulfone and silylated bisphenol-A two different scenarios were found. With CsF as catalyst at a temperature of more than 145°C cyclic oligoethers were formed under thermodynamic control. When the polycondensation was promoted with K2CO3 in N-methylpyrolidone at ?145°C the formation of cyclic oligoethers and polyethers occurred under kinetic control. A new mathematical formula is presented correlating the average degree of polymerization with the conversion and taking into account the competition between cyclization and propagation. PY - 2001 DO - https://doi.org/10.1088/0954-0083/13/2/312 SN - 0954-0083 SN - 1361-6412 VL - 13 SP - S123 EP - S136 PB - Sage Publ. CY - London AN - OPUS4-2178 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H. A1 - Probst, N. A1 - Schwarz, G. A1 - Schulz, Günter A1 - Krüger, Ralph-Peter T1 - New Polymer Syntheses - 107. Aliphatic Poly(thio ester)s by Ring-Opening Polycondensation of 2-Stanna-1,3-Dithiacycloalkanes N2 - We prepared 2,2-dibutyl-2-stanna-1,3-dithiacycloalkanes from dibutyltin oxide and ,-dimercaptoalkanes. Heterocycles with five-, six-, seven-, or nine-ring members were used as bifunctional monomers for polycondensations with aliphatic dicarboxylic acid chlorides. These polycondensations conducted in bulk were highly exothermic and yielded poly(thio ester)s with number average molecular weights (Mn's) in the range of 5000-30,000 Da. These poly(thio ester)s proved to be rapidly crystallizing materials with melting temperatures in the range of 90-150 °C. In addition to the success of the new synthetic approach, two interesting and unpredictable results were obtained. All volatile species detectable by matrix assisted laser desorption induced-time of flight (MALDI-TOF) mass spectrometry were cyclic oligo- and poly(thio ester)s. Second, several polyesters showed a reversible first-order change of the crystal modification as identified by differential scanning calorimetry measurements and X-ray scattering with variation of the temperature. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3656-3664, 2000 KW - Poly(thio-ester)s KW - Ring-opening polycondensation KW - Macrocycles KW - Change of crystal structure PY - 2000 DO - https://doi.org/10.1002/1099-0518(20001001)38:19<3656::AID-POLA190>3.0.CO;2-M SN - 0360-6376 SN - 0887-624X VL - 38 IS - 19 SP - 3656 EP - 3664 PB - Wiley CY - Hoboken, NJ AN - OPUS4-2170 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H.R. A1 - Vakhtangishvili, L. A1 - Schwarz, G. A1 - Schulz, Günter A1 - Krüger, Ralph-Peter T1 - Macrocycles 25. Cyclic poly(ether sulfone)s derived from 4-tert-butylcatechol N2 - Poly(ether sulfone)s were prepared by polycondensation of silylated 4-tert-butylcatechol and 4,4?-difluorodiphenylsulfone in N-methylpyrrolidone. The feed ratio and the reaction time were varied to study the influence of stoichiometry and conversion on molecular weight and extent of cyclization. Molecular weights and molecular weight distributions (MWD)s were characterized by SEC measurements calibrated with polystyrene. Light scattering confirmed that calibration with polystyrene gives reasonable results and revealed a tendency towards a bimodal MWD for the samples rich in cycles. The MALDI-TOF mass spectrometry indicated that the extent of cyclization increased with higher conversion and with optimization of the stoichiometry. This interpretation was confirmed by 1H NMR endgroup analyses. For the samples with the highest molar masses only mass peaks of cycles were found, which were detectable up to 20 000 Da before and up to 27 000 Da after fractionation. Via the pseudo-high dilution method low molar mass poly(ether sulfone) containing more than 95 mol% of cycles were prepared, and even these low molar mass samples had broad MWDs. DSC measurements indicated that the glass transition temperatures depend on the structure of the endgroups and increase with higher fractions of cycles. KW - Poly(ether sulfone)s KW - Polycondensation KW - MALDI-TOF mass spectrometry PY - 2003 DO - https://doi.org/10.1016/S0032-3861(03)00410-5 SN - 0032-3861 SN - 1873-2291 VL - 44 SP - 4471 EP - 4480 PB - Springer CY - Berlin AN - OPUS4-2623 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H.R. A1 - Vakhtangishvili, L. A1 - Schwarz, G. A1 - Krüger, Ralph-Peter T1 - Cyclic Hyperbranched Poly(ether ketone)s Derived from 3,5-Bis(4-fluorobenzoyl)phenol N2 - 3,5-Bis(4-fluorobenzoyl)phenol was polycondensed under various reaction conditions. Low molecular weights were obtained (Mn < 8000 Da), and MALDI-TOF mass spectrometry indicated that the chain growth was limited by cyclization. In the best mass spectra the cyclic, hyperbranched poly(ether ketone)s were detectable up to masses around 14 000 Da. When 4,4'-difluordiphenyl sulfone was added, star-shaped polymers having a diphenyl sulfone star center were formed, but cyclization was not completely suppressed. The results were compared to those obtained from "linear polycondensations" based on 4,4'-difluorobenzophenone (DFBP) and 4-tert-butylcatechol or bisphenol A. The poly(ether ketone)s of DFBP had also low molecular weights and contained high fractions of cycles. It is concluded that also in the case of hyperbranched polymers cyclization competes with propagation at any stage of the polycondensation at any concentration. Therefore, the fundamental trend of any "abn" polycondensation is the formation of star-shaped polymers having a cyclic core and hyperbranched star arms. PY - 2003 DO - https://doi.org/10.1021/ma021799x SN - 0024-9297 SN - 1520-5835 VL - 36 SP - 5551 EP - 5558 PB - American Chemical Society CY - Washington, DC AN - OPUS4-2622 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Lange, F. A1 - Hörmann, E. A1 - Schwarz, G. A1 - Droste, Bernhard A1 - Völzke, Holger A1 - Wieser, Günter T1 - Spent Fuel Transport and Storage Casks under Extreme Accidents T2 - 10th International High-Level Radioactive Waste Management Conference (IHLRWM-10) CY - Las Vegas, NV, USA DA - 2003-03-30 PY - 2003 SN - 0-89448-669-1 SP - 465 EP - 470 PB - American Nuclear Society CY - La Grange Park, Ill. AN - OPUS4-2698 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tödt, Fritz A1 - Schwarz, Wolfram A1 - Todt, H. G. T1 - Elektrochemische Bestimmung des Sauerstoffgehaltes von Oberflächengewässern PY - 1954 SN - 0932-6200 SN - 0016-9277 SN - 0720-9312 VL - 75 IS - 13/1 SP - 224 EP - 226 PB - Oldenbourg CY - München AN - OPUS4-9734 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schreiber, G. A1 - Schwarz, Wolfram T1 - Automatische Verfahren für elektrochemische Arbeiten. Die Aufnahme von U/1gI-Kurven PY - 1966 SN - 0013-4686 SN - 1873-3859 VL - 11 IS - 2 SP - 211 EP - 219 PB - Elsevier Science CY - Kidlington AN - OPUS4-10551 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, H. A1 - Chatti, S. A1 - Schwarz, G. A1 - Krüger, Ralph-Peter T1 - Macrocycles 27 - Cyclic Aliphatic Polyesters of Isosorbide N2 - Numerous polycondensations of isosorbide and suberoyl chloride or other aliphatic dicarboxylic acid dichlorides were performed with pyridine as a catalyst and HCl acceptor. The reaction conditions were varied to optimize both the molecular weight and the fraction of cyclic oligo- and polyesters. Furthermore, we attempted to obtain the cyclic monomer by catalyzed back-biting degradation of the molten cyclic polyesters above 220 °C in vacuo. The polyesters were characterized by viscosity and size exclusion chromatographic measurements as well as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. In selected cases, mixtures of linear and cyclic polyesters were treated with a hot solution of partially methylated ß-cyclodextrin in methanol. This treatment allowed for a selective extraction of the linear chains up to approximately 5000 Da. KW - Polycondensation KW - Cyclization KW - Isosorbide KW - Polyesters KW - MALDI PY - 2003 DO - https://doi.org/10.1002/pola.10933 SN - 0360-6376 SN - 0887-624X VL - 41 IS - 21 SP - 3414 EP - 3424 PB - Wiley CY - Hoboken, NJ AN - OPUS4-12017 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schwarz, G. A1 - Weller, Michael G. A1 - Benda, D. A1 - Linscheid, M. T1 - MeCAT – Analysis of labeled proteins by HighMass-Q-TOF-MS T2 - Joint Conference of PMSS and DGMS CY - Poznan, Poland DA - 2012-03-04 PY - 2012 AN - OPUS4-26037 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schoknecht, Ute A1 - Fürhapper, C. A1 - Gunschera, J. A1 - Härtner, H. A1 - Hill, R. A1 - Melcher, E. A1 - Schwarz, G. A1 - Spetmann, P. A1 - Wilken, U. A1 - Wittenzellner, J. A1 - Wobst, M. T1 - Bestimmung von Permethrin in Holz - Ergebnisse von Vergleichsanalysen N2 - Vergleichsanalysen zur Bestimmung von Permethrin aus Holz ergaben, dass sich sowohl Extraktion mit Methanol im Ultraschallverfahren als auch Soxhlet-Extraktion mit Ethylacetat gut eignen, um Permethrin aus behandeltem Holz zu lösen. Verschiedene andere Extraktionsverfahren führen zu Minderbefunden. Zur quantitativen Bestimmung von Permethrin können sowohl Hochdruckflüssigchromatographie als auch Gaschromatographie eingesetzt werden. KW - Permethrin KW - Holz KW - Extraktion KW - Gaschromatographie KW - Hochdruckflüssigchromatographie KW - Analyse PY - 2008 DO - https://doi.org/10.1007/s00107-007-0208-2 SN - 0018-3768 VL - 66 IS - 1 SP - 57 EP - 61 PB - Springer CY - Berlin AN - OPUS4-17167 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schwarz, G. A1 - Weller, Michael G. A1 - Beck, S. A1 - Schuschke, K. A1 - Linscheid, M. A1 - Schalley, C. A. T1 - MeCAT - Identification and quantification of proteins in human serum T2 - Annual meeting DGMS CY - Dortmund, Germany DA - 2011-09-21 PY - 2011 AN - OPUS4-26040 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schwarz, G. A1 - Müller, Larissa A1 - Beck, S. A1 - Linscheid, M.W. T1 - DOTA based metal labels for protein quantification: a review N2 - Today, quantitative data play a pivotal role in the understanding of biological processes. This is particularly true for the proteome: protein quantification always follows protein identification. To obtain useful and reliable quantitative data, rather sophisticated strategies using electrospray and MALDI mass spectrometry have been developed, which allow relative and sometimes even absolute quantification. All of those strategies have merits and limitations. In order to overcome some of these limits, methods based on the reliable and sensitive detection and quantification of heavy metals present in proteins using inductively coupled plasma (ICP)-MS have been reported. With specific labels carrying heavy metals, the applicability of ICP-MS has been extended to almost every protein. One of such covalently bound metal tags, allowing the quantification of low abundant proteins, uses 1,4,7,10-tetraazacyclododecane N,N',N'',N''-tetraacetic acid (DOTA) chelate complexes carrying lanthanides as the metal core. In this review the scope and limitations of peptide and protein quantification will be addressed. The metal tags do not only provide low detection limits, but also due to the large number of different lanthanides and lanthanide isotopes, multiplexing capabilities and previously unknown accuracy based on inherently possible isotope dilution methods came into reach. The developed workflows, including electrophoretic and chromatographic separation and preconcentration techniques, will be addressed to allow a comparison with already established procedures. KW - Protein quantification KW - ICP-MS KW - DOTA KW - Labeling PY - 2014 DO - https://doi.org/10.1039/c3ja50277e SN - 0267-9477 SN - 1364-5544 VL - 29 IS - 2 SP - 221 EP - 233 PB - Royal Society of Chemistry CY - London AN - OPUS4-30730 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schwarz, Gunnar A1 - Beck, S. A1 - Weller, Michael G. A1 - Linscheid, M.W. T1 - MeCAT - new iodoacetamide reagents for metal labeling of proteins and peptides N2 - Besides protein identification via mass spectrometric methods, protein and peptide quantification has become more and more important in order to tackle biological questions. Methods like differential gel electrophoresis or enzyme-linked immunosorbent assays have been used to assess protein concentrations, while stable isotope labeling methods are also well established in quantitative proteomics. Recently, we developed metalcoded affinity tagging (MeCAT) as an alternative for accurate and sensitive quantification of peptides and proteins. In addition to absolute quantification via inductively coupled plasma mass spectrometry, MeCAT also enables sequence analysis via electrospray ionization tandem mass spectrometry. In the current study, we developed a new labeling approach utilizing an iodoacetamide MeCAT reagent (MeCAT-IA). The MeCAT-IA approach shows distinct advantages over the previously used MeCAT with maleinimide reactivity such as higher labelling efficiency and the lack of diastereomer formation during labeling. Here, we present a careful characterization of this new method focusing on the labeling process, which yields complete tagging with an excess of reagent of 1.6 to 1, less complex chromatographic behavior, and fragmentation characteristics of the tagged peptides using the iodoacetamide MeCAT reagent. KW - Quantitative proteomics KW - Mass spectrometry KW - Metal labeling KW - Stable isotope labeling KW - Lanthanide DOTA KW - Metall-Markierung KW - Reagenzien KW - Protein-Quantifizierung KW - Lanthaniden KW - Multiplexing PY - 2011 DO - https://doi.org/10.1007/s00216-011-5189-7 SN - 1618-2642 SN - 1618-2650 VL - 401 IS - 4 SP - 1203 EP - 1209 PB - Springer CY - Berlin AN - OPUS4-23949 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schwarz, G. A1 - Weller, Michael G. A1 - Beck, S. A1 - Linscheid, M. T1 - MeCAT - new iodoacetamide reagents for metal labeling of proteins and peptides T2 - Metallomics Conference 2011 CY - Münster, Germany DA - 2011-06-15 PY - 2011 AN - OPUS4-24006 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schwarz, G. A1 - Weller, Michael G. A1 - Weber, R. A1 - Linscheid, M. T1 - Introducing MeCAT with iodine reactivity for cysteine labeling of proteins and peptides T2 - Annual meeting DGMS CY - Halle (Saale), Germany DA - 2010-03-07 PY - 2010 AN - OPUS4-26042 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schwarz, G. A1 - Weller, Michael G. A1 - Beck, S. A1 - Linscheid, M. T1 - MeCAT - Reagents for cysteine labeling of proteins and peptides T2 - 3rd International Symposium on Metallomics CY - Münster, Germany DA - 2011-06-15 PY - 2011 AN - OPUS4-26039 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schwarz, G. A1 - Weller, Michael G. A1 - Benda, D. A1 - Linscheid, M. T1 - MeCAT – Fragmentation behavior of labeled peptides and relative quantification T2 - Joint Conference of PMSS and DGMS CY - Poznan, Poland DA - 2012-03-04 PY - 2012 AN - OPUS4-26038 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schwarz, G. A1 - Weller, Michael G. A1 - Beck, S. A1 - Linscheid, M. T1 - MeCAT - Iodine reactivity for cysteine labeling of proteins and peptides T2 - Annual meeting DGMS CY - Dortmund, Germany DA - 2011-09-21 PY - 2011 AN - OPUS4-26041 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -