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1.
2.
In bioanalytical LC-MS-MS matrix effects influencing the ionization process are a major concern with respect to the quality of the results obtained. In general such matrix effects are directly related to an insufficient sample clean-up of the biofluids. In order to establish a MS-adequate clean-up procedure for basic analytes present in biofluids (e.g. urine, plasma) which is based on solid-phase extraction (SPE) principles a combination of tailor-made SPE column packings and automated column-switching was developed. This novel, multidimensional (MD) SPE platform relies on the combination of a SPE column packed with a restricted access material (RAM) allowing size-exclusion and reversed phase chromatography (SEC-RPC) and a second SPE column packed with a mixed-mode phase (MMP) allowing ion exchange and reversed phase chromatography (IEX-RPC). For the evaluation of this MD-SPE platform 8 tricyclic antidepressants and two metabolites were chosen as model analytes. In order to monitor matrix effects, i.e. ion suppression, postcolumn infusion experiments were performed and compared with a two-dimensional SPE column mode (SEC-RPC). The MD-SPE platform is highly efficient for removal of low and high molecular weight sample components which suppress ionization to varying extend. In addition electrospray ionization of the model analytes is not affected by inter- or intra-individual variations in the composition of the matrix investigated. It is also independent of the species the biofluids originate from. It was demonstrated that the MD-SPE platform has a generic potential with respect to on-line SPE of basic drugs having a pKa > 6.5 and a moderate to low polarity and being present in different biofluids. 相似文献
3.
Karl-Siegfried Boos Anne Rudolphi Stefan Vielhauer Andreas Walfort Dieter Lubda Friedhelm Eisenbeiß 《Fresenius' Journal of Analytical Chemistry》1995,352(7-8):684-690
The direct and repetitive injection of untreated biological fluids (e.g., hemolyzed blood, plasma, serum, cell culture and tissue homogenates) onto an HPLC-system and the subsequent analysis of low-molecular weight compounds (e.g. drugs, xenobiotics, metabolites) is rendered possible by a coupled-column configuration and special precolumn packings. For this purpose a new family of chemically and enzymatically tailored reversed-phase packing materials have been prepared. The LC-integrated sample clean-up with these restricted access (bimodal) phases is based on the complete nonadsorptive size exclusion of macromolecules (e.g. proteins) and on the simultaneous dynamic partitioning of the target molecules. The bonded phase which exclusively covers the internal pore surface of a glyceryl-modified silica is a butyryl-(C-4), capryloyl-(C-8) or stearoyl-(C-18) moiety. These ligands allow a classical reversed-phase or ion-pair chromatography during the sample work-up step. The capacity of the n-alkyl phase is comparable with conventional silica based RP-materials. The broad hydrophobic retentive capability of these packings allows the extraction of a wide variety of compounds of biomedical interest. The electroneutral and hydrophilic particle exterior (glyceryl-residues) was generated using either soluble or immobilized enzymes (lipase, esterase) which cleave the fatty acid esters exclusively at the outer surface. Unwanted macromolecular components of a sample (e.g. proteins) are quantitatively eluted in the void volume due to the restricted access given by the pore size (6 nm) and the nonadsorptive external diol coverage. The lifetime of a precolumn (25 × 4 mm I.D.) packed with these novel bimodal, i.e. RP-SEC phases exceeds more than 200 injections of 500 l plasma. In addition to the synthesis, this paper describes an application of each of these Alkyl-Diol Silica (ADS) precolumn packings in fully automated coupled-column HPLC systems for the analysis of drugs and endogenous compounds in different biological matrices.Dedicated to Professor Dr. Dr. h.c. mult. J.F.K. Huber on the occasion of his 70th birthday 相似文献
4.
Yu. I. Sal’nikov G. A. Boos I. S. Ryzhkina S. S. Lukashenko A. N. Tiforova 《Colloid Journal》2005,67(4):478-484
The influence of Triton X-100 (concentration 5 mM) on acid-base properties of aminomethylated calix[4]resorcinarene (H8L) containing alkyl (R1 = C11H23) and dimethylaminomethyl (R2 = CH2N(CH3)2) substituents and interaction of H8L with copper(II) is studied by potentiometry and mathematical simulation of equilibria in solutions. It is found that the presence of a nonionic surfactant favors the aggregation of H8L (the degree of aggregation is higher than four), whereas, in 80% isopropanol at the same pH ≈ 10.2, a neutral species of the compound is only dimerized. The addition of Triton X-100 affects both the composition and stability of formed copper(II) complexes. The fraction of the highly charged tetranuclear [Cu4(H4L)]4+ complex sharply decreases. The formation of a large amount of [Cu(H7L)]+ complex appears to be preferable compared to [Cu(H8L)2]2+ complex containing two ligands in the coordination sphere (pH ≈ 5.7). An enhancement of the acidic properties of protonated species of the compound and a decrease in the apparent constants of H8L-copper(II) complex formation in Triton X-100 solutions compared to those in water-alcohol solutions are attributed to the formation of mixed micelles.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 4, 2005, pp. 527–533.Original Russian Text Copyright © 2005 by Sal’nikov, Boos, Ryzhkina, Lukashenko, Tiforova. 相似文献
5.
R. Menges U. Dinger N. Boos G. Huber S. Schröder S. Dutta R. Kirchner O. Klepper T. Kühl D. Marx G. D. Sprouse 《Zeitschrift für Physik A Hadrons and Nuclei》1992,341(4):475-479
The hyperfine structure, isotope and isomeric shifts in the atomic transition 6p
2
P
3/2–7s
2
S
1/2, =535 nm have been measured for theI=7 andI=2 states of190, 192, 194, 196Tl; theI=1/2 andI=9/2 states of191Tl and the I=7 isomer of188Tl. The thallium isotopes were prepared as fast atomic beams at the GSI on-line mass separator following fusion reactions and — in some cases — subsequent-decay. The nuclear dipole moments, electric quadrupole moments and the change in the nuclear mean square charge radius are evaluated. Theuu-isotopes show an isomeric shift which changes sign between192Tl and194Tl.Dedicated to P. Armbruster on the occasion of his 60th birthday 相似文献
6.
J. Bartel D. Boosé K. Dietrich K. Pomorski J. Richert 《Zeitschrift für Physik A Hadrons and Nuclei》1991,339(1):155-170
Giant shape vibrations of fission fragments are described in a simple model which is based on nuclear transport theory. The friction and inertial parameters are calculated within the linear response and cranking theory, respectively. The initial conditions are chosen in the scission region following the conventional picture of the fission process at low energy. The emission of electromagnetic radiation by the form vibration is treated classically.Dedicated to Prof. Dr. H.J. Mang on the occasion of his 60th birthday 相似文献
7.
V. F. Mironov Yu. I. Sal’nikov G. A. Boos D. A. Tatarinov A. P. Nikitin 《Russian Journal of General Chemistry》2013,83(6):1087-1093
Four new compounds, asymmetrical phosphine oxides containing 2-hydroxyphenylethenyl fragment in cis-orientation with respect to the phosphine oxide: dibutyl-, diphenyl-, dibenzyl-, and dinaphthyl-2-(2-hydroxy-5-chlorophenyl)-2-phenyl-ethenylphospnine oxides, have been studied in aqueous ethanol (80 vol % of EtOH) by means of potentiometry and spectrophotometry at 25±0.1°C, and their acid-base and complexing properties estimated. 相似文献
8.
V. V. Neklyudov G. A. Boos S. G. Fattakhov G. A. Chmutova M. M. Shulaeva Yu. I. Salnikov 《Russian Journal of General Chemistry》2013,83(7):1369-1375
Solutions of a new drug, 2,4-diamino-6-(acetylhydrazidomethylsulfonylmethyl)-1,3,5-triazine, exhibiting tuberculocidal activity were studied using the methods of pH-metry, spectrophotometry, mathematical simulation of equilibria (CPESSP software), and molecular mechanics. Protolytic properties of the compound in the medium of aqueous dimethylsulfoxide (40 vol % of DMSO) were characterized. The composition of the copper(II) complex of this compound was determined and its stability constants were calculated. Based on the absorption spectra in the UV and visible regions the complexing ability of 2,4-diamino-6-(acetylhydrazidomethylsulfonylmethyl)-1,3,5-triazine toward nickel(II) and cobalt(II) were characterized in comparison with copper(II) under the same conditions. 相似文献
9.
10.
A novel, multidimensional SPE sample-processing platform for complex fluids, which relies on the combination of small LC columns packed with restricted access materials (RAM) and molecular imprinted polymers (MIP) is described. It is called the Six-S ProcEdure (Six-SPE). Six-SPE involves a size-selective sample-separation step followed by a solvent-switch. Six-SPE efficiently removes interfering matrix components of complex aqueous samples and creates optimal conditions for selective recognition, i.e. binding of the imprinted target analyte(s). A Six-SPE analysis cycle consists of four distinct steps: 1. separation of a given sample (e.g. plasma, urine, saliva, milk, etc.) by adsorptive extraction (e.g. reversed-phase partitioning) of low molecular weight components on to the stationary phase of a RAM column and simultaneous size-exclusion, i.e. quantitative disposal of macromolecular matrix constituents to waste; 2. desorption and transfer of the extract from the RAM column on to a series-connected MIP column using a pure organic mobile phase (e.g. acetonitrile) [solvent switch]; 3. molecular recognition, i.e. selective binding of the target analyte(s) by a tailor-made MIP column; and 4. desorption and transfer of the analyte fraction on to a series-connected separation (e.g. HPLC) and/or detection system (e.g. UV, FD, MS). As a first application we coupled the Six-SPE platform to a conventional HPLC system for on-line analysis of the analgesic drug Tramadol in human plasma using LiChrospher ADS RP-18 as a RAM precolumn for the fractionation step in the first and second chromatographic dimension and a Tramadol imprinted polymer for the molecular recognition step, i.e. third chromatographic dimension. 相似文献