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Quaternary Amines (quaternary + amine)
Selected AbstractsComparative metabolite profiling of carboxylic acids in rat urine by CE-ESI MS/MS through positively pre-charged and 2H-coded derivatizationELECTROPHORESIS, Issue 22 2008Wen-Chu Yang Abstract A new approach to the selective comparative metabolite profiling of carboxylic acids in rat urine was established using CE-MS and a method for positively pre-charged and 2H-coded derivatization. Novel derivatizing reagents, N -alkyl-4-aminomethyl-pyridinum iodide (alkyl=butyl, butyl-d9 or hexyl), containing quaternary amine and stable-isotope atoms (deuterium), were introduced for the derivatization of carboxylic acids. CE separation in positive polarity showed high reproducibility (0.99,1.32% RSD of migration time) and eliminated problems with capillary coating known in CE-MS anion analyses. Essentially complete ionization and increased hydrophobicity after the derivatization also enhanced MS detection sensitivity (e.g. formic acid was detected at 0.5,pg). Simultaneous derivatization of one sample using two structurally similar reagents, N -butyl-4-aminomethyl-pyridinum iodide (BAMP) and N -hexyl-4-aminomethyl-pyridinum iodide, provided additional information for recognizing a carboxylic acid in an unknown sample. Moreover, characteristic fragmentation acquired by online CE-MS/MS allowed for identification and categorization of carboxylic acids. Applying this method on rat urine, we found 59 ions matching the characteristic patterns of carboxylic acids. From these 59, 32 ions were positively identified and confirmed with standards. For comparative analysis, 24 standard carboxylic acids were derivatized by chemically identical but isotopically distinct BAMP and N -butyl-d9-4-aminomethyl-pyridinium iodide, and their derivatization limits and linearity ranges were determined. Comparative analysis was also performed on two individual urine samples derivatized with BAMP and N -butyl-d9-4-aminomethyl-pyridinium iodide. The metabolite profiling variation between these two samples was clearly visualized. [source] New once-daily formulation for trospium in overactive bladderINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 11 2010C. Chapple Summary Aims:, We examined the relative efficacy and safety of trospium 20 mg bid and 60 mg extended release formulations and position this drug against other antimuscarinic agents. Methods:, Data were identified on the pharmacology and pharmacokinetics of trospium chloride. Key publications on trospium 20-mg and 60-mg clinical studies in patients with overactive bladder (OAB) were identified and efficacy and safety compared between these formulations as well as other antimuscarinic agents. Results:, Trospium offers the principal advantage over other antimuscarinic agents that, as it is a quaternary amine, it does not cross the blood,brain barrier and is therefore less likely to cause central nervous system effects observed with several other agents. Moreover, with its minimal liver metabolisation, independent of the main cytochrome pathways, trospium has a low risk of drug,drug interaction in patients taking multiple pharmacological agents. Trospium 60 mg ER is as effective as trospium 20 mg bid in improving the key outcome parameters associated with OAB, but with a lower rate of dry mouth, the most common side effect of these agents. Trospium has comparable efficacy and safety to the other antimuscarinic agents currently marketed. Discussion:, Good patient persistence with treatment has been reported with trospium. There are currently a large number of antimuscarinic drugs on the market without clear evidence to distinguish one agent from another in terms of efficacy, provided that an adequate dose is used in the clinical setting. Conclusion:, The new formulation of trospium is certainly worth considering as a pharmacological treatment of patients with OAB, particularly in the elderly, in whom one wants to avoid the potential for cognitive dysfunction. [source] Salt tolerant membrane adsorbers for robust impurity clearanceBIOTECHNOLOGY PROGRESS, Issue 6 2009William T. Riordan Abstract Clearance of impurities such as viruses, host cell protein (HCP), and DNA is a critical purification design consideration for manufacture of monoclonal antibody therapeutics. Anion exchange chromatography has frequently been utilized to accomplish this goal; however, anion exchange adsorbents based on the traditional quaternary amine (Q) ligand are sensitive to salt concentration, leading to reduced clearance levels of impurities at moderate salt concentrations (50,150 mM). In this report, membrane adsorbers incorporating four alternative salt tolerant anion exchange ligands were examined for impurity clearance: agmatine, tris-2-aminoethyl amine, polyhexamethylene biguanide (PHMB), and polyethyleneimine. Each of these ligands provided greater than 5 log reduction value (LRV) for viral clearance of phage ,X174 (pI , 6.7) at pH 7.5 and phage PR772 (pI , 4) at pH 4.2 in the presence of salt. Under these same conditions, the commercial Q membrane adsorber provided no clearance (zero LRV). Clearance of host-cell protein at pH 7.5 was the most challenging test case; only PHMB maintained 1.5 LRV in 150 mM salt. The salt tolerance of PHMB was attributed to its large positive net charge through the presence of multiple biguanide groups that participated in electrostatic and hydrogen bonding interactions with the impurity molecules. On the basis of the results of this study, membrane adsorbers that incorporate salt tolerant anion exchange ligands provide a robust approach to impurity clearance during the purification of monoclonal antibodies. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] The removal of reactive azo dyes by natural and modified zeolitesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2003B Arma Abstract The adsorption mechanism of three reactive dyes by zeolite has been examined with the aim of identifying the ability of zeolite to remove textile dyes from aqueous solutions. Towards this aim, a series of batch adsorption experiments was carried out, along with determination of the electrokinetic properties of both natural and modified zeolites. The adsorbent in this study is a clinoptilolite from the Gördes region of Turkey. The reactive dyes CI Reactive Black 5, Red 239 and Yellow 176 are typical azo dyes extensively used in textile dyeing. Adsorption tests were carried out as a function of mixing time, solids concentration, dye concentration and pH. The adsorption results indicate that the natural zeolite has a limited adsorption capacity for reactive dyes but is substantially improved upon modifying its surfaces with quaternary amines. An electrostatic adsorption mechanism involving the formation of a bilayer of amine molecules on the clinoptilolite surface onto which anionic dye molecules adsorb, depending on their polarities, is proposed. The results are also supported by electrokinetic measurements. The adsorption data were fitted to the Langmuir isotherm and it was found that the modified sepiolite yields adsorption capacities (qe) of 111, 89 and 61 mg g,1 for Red, Yellow and Black, respectively. These results are comparable to a popular adsorbent, activated carbon. Copyright © 2003 Society of Chemical Industry [source] Quantitative determination of alkylated quaternary amines and their n -hydroxylated metabolites in an enzyme incubation matrix by liquid chromatography electrospray ionization mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 8 2005Victoria E. Holmes Abstract A simple, rapid and sensitive reversed-phase liquid chromatography method coupled to electrospray ionization mass spectrometry has been developed for studying the in vitro metabolism of the long-chain quaternary ammonium compounds dodecyltrimethylamine, tetradecyltrimethylamine and hexadecyltrimethylamine. Samples were prepared from the biological matrix by a simple protein precipitation stage. The separation was performed using a BDS Hypersil C8 3 µm particle size (100 × 3 mm i.d.) column with a fast gradient separation (60% B to 100% B) using a mobile phase of 10 mm aqueous ammonium acetate (pH 4.0, with 0.06% triethylamine; (A),acetonitrile (B) at 0.7 mL min,1. To minimize contamination of the MS source a switching value was used to divert the solvent front to waste. Decylammonium bromide was used as the internal standard and analytes were identified and quantified by positive ion electrospray selected ion monitoring of their intact molecular cations. The assay had a limit of quantitation of 0.25 µm (6.25 pmol on column) and was linear over the range 0.25,100 µm assay concentration for this series of long-chain quaternary amines. The precision of intra- and inter-day assays was better than 19% and the accuracy was between 93 and 109%. The method was used to assess the in vitro metabolism of the quaternary amines by wild-type cytochrome P450 enzyme CYP4A1 and mutants in an artifical membrane system. Copyright © 2005 John Wiley & Sons, Ltd. [source] | |||||||||||||