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Mallakpour S, Zadehnazari A. Synthesis of Optically Active and Thermally Stable Polyamides With Bulky Aromatic Side Chain in an Ionic Liquid (Tetrabutylammonium Bromide). HIGH PERFORM POLYM 2009. [DOI: 10.1177/0954008309348219] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A new class of wholly aromatic and optically active polyamides (PAs) having phthalimide and L-leucine pendant groups were synthesized via polycondensation of chiral diacid, (2S)-5-[4-(4-methyl2-phthalimidylpentanoyl-amino)benzoylamino]isophthalic acid and different aliphatic and aromatic diisocyanates. Polymerization reactions were performed both in the presence of dibutyltin dilaurate as a catalyst and without a catalyst, using molten tetrabutylammonium bromide (TBAB) as a green solvent, and was compared with polymerization in 1-methyl-2-pyrrolidone as a conventional solvent. The resulting polymers were obtained in good yields and inherent viscosities ranging between 0.26 and 0.96 dL g-1. These polymers are optically active, thermally stable and readily soluble in amide-type solvents. All of the above polymers were characterized by Fourier transform infrared spectroscopy, specific rotation and in some cases by 1H-NMR and elemental analysis techniques. Thermal properties of PAs were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry. TGA showed that the 5% weight loss temperature in a nitrogen atmosphere for two representative samples were more than 283 and 354 °C, which indicates that the resulting PAs have good thermal stability.
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Affiliation(s)
- Shadpour Mallakpour
- Organic Polymer Chemistry Research Laboratory, Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111, I.R. Iran, , ,
| | - Amin Zadehnazari
- Organic Polymer Chemistry Research Laboratory, Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111, I.R. Iran
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Olsen R, Øvrebø S, Thorud S, Lundanes E, Thomassen Y, Greibrokk T, Molander P. Sensitive determination of a glyoxal–DNA adduct biomarker candidate by column switching capillary liquid chromatography electrospray ionization mass spectrometry. Analyst 2008; 133:802-9. [DOI: 10.1039/b719842f] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Affiliation(s)
- Brian A. Jones
- a Selerity Technologies, Inc. , 2484 W. Custer Road, Salt Lake City , Utah , 84104 , USA
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Henneken H, Vogel M, Karst U. Determination of airborne isocyanates. Anal Bioanal Chem 2006; 387:219-36. [PMID: 17103147 DOI: 10.1007/s00216-006-0901-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 10/01/2006] [Accepted: 10/02/2006] [Indexed: 11/29/2022]
Abstract
Isocyanates are important in industrial hygiene and workplace monitoring. Owing to their severe acute toxicity and sensitizing properties, analytical methods with high sampling efficiency and sensitivity in the low ppb to ppt range are required. The reactivity of isocyanates necessitates initial derivatization with nucleophilic agents--usually amines--for stabilization and enrichment; this is often followed by chromatographic separation with spectroscopic, electrochemical, or mass spectrometric detection. Sampling strategies for airborne isocyanates comprise active, i.e. pumped, or passive, i.e. diffusive, methods; the method selected depends on the application. Whereas active methods rely mainly on impingers, reagent-coated filters, or sampling tubes, passive samplers make use of reagent-coated filters, the surface of which is connected to the air sample by diffusion channels. Because airborne isocyanates are prone to occur in different forms, i.e. as vapors, as aerosols, or adsorbed on particulate matter, denuder sampling has been introduced, thus enabling simultaneous collection of gaseous and aerosol isocyanates. The first part of this review summarizes chemical methods and reagents which have been introduced for derivatization of airborne isocyanates. The advantages and drawbacks of the individual derivatization procedures and their combination with different detection principles are evaluated. In the second part, the most recent developments in air sampling for isocyanates, with special focus on diffusive sampling, are reviewed and critically discussed.
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Affiliation(s)
- Hartmut Henneken
- Department of Chemical Analysis and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
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Murata K, Mano N, Asakawa N. Development of a large-volume, membrane-based injection system for gradient elution micro-liquid chromatography. J Chromatogr A 2006; 1106:146-51. [PMID: 16213510 DOI: 10.1016/j.chroma.2005.09.047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Revised: 09/15/2005] [Accepted: 09/21/2005] [Indexed: 11/23/2022]
Abstract
A membrane unit which can be used to inject a large volume of sample solution was developed to facilitate reproducible and accurate gradient elution in micro-high-performance liquid chromatography (micro-HPLC). Since the membrane unit has a very low void volume, it facilitates the effective concentration of analytes in large sample volumes. Gradient elution micro-HPLC with the membrane unit allowed the efficient separation of n-alkyl benzoates, used as test samples, in a short time without marked gradient delay. In this study, the membrane unit could be loaded with up to 50 microg of n-hexyl benzoate, and more than 500 microL of sample solution could be applied. In about 50 chromatographic runs, the relative standard deviation (RSD) of the relative retention time of n-hexyl benzoate with respect to methyl benzoate was 0.530%.
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Affiliation(s)
- Kaoru Murata
- Analytical Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan.
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Olsen R, Sagredo C, Ovrebø S, Lundanes E, Greibrokk T, Molander P. Determination of benzo[a]pyrene tetrols by column-switching capillary liquid chromatography with fluorescence and micro-electrospray ionization mass spectrometric detection. Analyst 2005; 130:941-7. [PMID: 15912244 DOI: 10.1039/b419145e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The present work displays capillary liquid chromatographic column switching methodology tailored for determination of benzo[a]pyrene tetrol isomers in biological matrices using on-line fluorescence and micro-electrospray ionization mass spectrometric detection. A well-established off-line crude solid phase extraction procedure was used in order to make the method compatible with several biological matrices. The solid phase extraction eluates were evaporated to dryness, redissolved in 1.0 ml methanol:water (10:90, v/v), loaded onto a 0.32 mm I.D. x 40 mm 5 microm Kromasil C(18) pre-column for analyte enrichment and back-flushed elution onto a 0.30 mm I.D. x 150 mm 3.5 microm Kromasil C(18) analytical column. The samples were loaded with a flow rate of 50 microl min(-1) and the tetrols were separated at a flow rate of 4 microl min(-1) with an acetonitrile:10 mM ammonium acetate gradient from 10 to 90%. A sample loading flow rate up to 50 microl min(-1) was allowed. The fluorescence excitation and emission were set to 342 and 385 nm, respectively, while mass spectrometric detection of the benzo[a]pyrene tetrols was obtained by monitoring their [M - H](-) molecular ions at m/z 319. The method was validated over the concentration range 0.1-50 ng ml(-1) benzo[a]pyrene tetrols in a cell culture medium with 100 microl injection volume, fluorescence detection and the first eluting tetrol isomer as model compound, resulting in a correlation coefficient of 0.993. The within-assay (n= 6) and between-assay (n= 6) precisions were determined to 2.6-8.6% and 3.8-9.6%, respectively, and the recoveries were determined to 97.9-102.4% within the investigated concentration range. The mass limit of detection (by fluorescence) was 3 pg for all the tetrol isomers, corresponding to a concentration limit of detection of 30 pg ml(-1) cell culture medium. The corresponding mass spectrometric mass limits of detection were 4-10 pg, corresponding to concentration limits of detection of 40-100 pg ml(-1) cell culture medium.
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Affiliation(s)
- Raymond Olsen
- National Institute of Occupational Health, Oslo, Norway
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Jandera P, Blomberg LG, Lundanes E. Controlling the retention in capillary LC with solvents, temperature, and electric fields. J Sep Sci 2004; 27:1402-18. [PMID: 15638149 DOI: 10.1002/jssc.200401852] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Once a suitable stationary phase and column dimensions have been selected, the retention in liquid chromatography (LC) is traditionally adjusted by controlling the mobile phase composition. Solvent gradients enable achievement of good separation selectivity while decreasing the separation time as compared to isocratic elution. Capillary columns allow use of other programming parameters, i.e. temperature and applied electric fields, in addition to solvent gradient elution. This paper presents a review of programmed separation techniques in miniaturized LC, including retention modeling and method transfer from the conventional to micro- and capillary scales. The impact of miniaturized instrumentation on retention and the limitations of capillary LC are discussed. Special attention is focused on the gradient dwell volume effects, which are more important in micro-LC techniques than in conventional analytical LC and may cause significant increase in the time of analysis, unless special instrumentation and (or) pre-column flow-splitting is used. The influence of temperature upon retention is also discussed, and applications where the temperature has been actively used for retention control in capillary LC are included together with the instrumentation utilized. Finally the possibilities of additional selectivity control by applying an electric field over a packed capillary LC column are discussed.
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Affiliation(s)
- Pavel Jandera
- Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice Nám Cs legii 565, CZ 532 10 Pardubice, Czech Republic
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Holm A, Molander P, Lundanes E, Øvrebø S, Greibrokk T. Fast and sensitive determination of urinary 1-hydroxypyrene by packed capillary column switching liquid chromatography coupled to micro-electrospray time-of-flight mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 794:175-83. [PMID: 12888210 DOI: 10.1016/s1570-0232(03)00427-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The present work reports capillary liquid chromatographic column switching methodology tailored for fast, sensitive and selective determination of 1-hydroxypyrene (1-OHP) in human urine using micro-electrospray ionization time-of-flight mass spectrometric detection. Samples (100 microl) of deconjugated, water diluted and filtered urine samples were loaded onto a 150 microm I.D.x 30 mm 10 microm Kromasil C(18) pre-column, providing on-line sample clean-up and analyte enrichment, prior to back flushed elution onto a 150 microm I.D.x 100 mm 3.5 microm Kromasil C(18) analytical column. Loading flow rates up to 100 microl/min in addition to the use of isocratic elution by a mobile phase composition of acetonitrile/water (70/30, v/v) containing 5 mM ammonium acetate provided elution of 1-OHP within 5.5 min and a total analysis time of less than 15 min with manual operation. Ionization was performed in the negative mode and 1-OHP was observed as [M-H](-) at m/z 217.08. The method was validated over the concentration range 0.2-40 ng/ml 1-OHP in pre-treated urine, yielding a coefficient of correlation of 0.997. The within-assay (n=6) and between-assay (n=6) precisions were in the range 6.4-7.3 and 7.0-8.1%, respectively, and the recoveries were in the range 96.2-97.5 within the investigated concentration range. The method mass limit of detection was 2 pg, corresponding to a 1-OHP concentration limit of detection of 20 pg/ml (0.09 nmol/l) diluted urine or 0.3 ng/ml (1.35 nmol/l) urine.
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Affiliation(s)
- Anders Holm
- Department of Chemistry, University of Oslo, PO Box 1033, Blindern, N-0315, Oslo, Norway.
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Abstract
The present state of the active use of elevated temperatures in liquid chromatography is reviewed, including the effects on retention, selectivity and efficiency. Separations in aqueous mobile phases as well as non-aqueous media are discussed, with particular emphasis on narrow-bore columns.
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Affiliation(s)
- Tyge Greibrokk
- Department of Chemistry, University of Oslo, POB 1033 Blindern, N-0315 Oslo, Norway.
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Holm A, Molander P, Lundanes E, Greibrokk T. Determination of rotenone in river water utilizing packed capillary column switching liquid chromatography with UV and time-of-flight mass spectrometric detection. J Chromatogr A 2003; 983:43-50. [PMID: 12568369 DOI: 10.1016/s0021-9673(02)01693-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Fast and sensitive packed capillary column switching liquid chromatography methodology has been developed for the determination of the pesticide rotenone in river water. Sample volumes of up to 1 ml are loaded onto a 23 x 0.25 mm, 5 microm Kromasil C18 packed capillary precolumn using a noneluting solvent composition of water-acetonitrile (99:1, v/v) at flow-rates up to 100 microl/min prior to solute backflushing onto a 200 x 0.32 mm, 3.5 microm Kromasil C18 packed capillary analytical column using a mobile phase of water-acetonitrile (30:70, v/v) at a flow-rate of 5 microl/min. The method was evaluated using river water samples spiked with rotenone in the concentration range 0.5-50 ng/ml using UV detection. The within-assay precision was between 5.0 and 7.7% relative standard deviation (RSD, n = 6) and the between assay precision was between 7.5 and 8.9% RSD (n = 6). The method was linear within the investigated mass range displaying a calibration curve correlation factor of 0.997. The mass limit of detection was 10 pg corresponding to a concentration limit of detection of 10 pg/ml, using time-of-flight mass spectrometry.
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Affiliation(s)
- A Holm
- Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315, Norway.
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Paal DM, Levin JO, Ostin A, Rosenberg C, Henriks-Eckerman ML, Brødsgaard S, Thorud SHS, Fladseth G, Thomassen Y. Harmonized Nordic strategies for isocyanate monitoring in workroom atmospheres. JOURNAL OF ENVIRONMENTAL MONITORING : JEM 2002; 4:685-7. [PMID: 12400915 DOI: 10.1039/b203393c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Nordic Network on Isocyanates (NORDNI) is financed by the Nordic Council of Ministers and is under the administration of Prof. Yngvar Thomassen and co-workers. National Institute of Occupational Health, Norway. The aim of NORDNI is to establish a broad network between the Nordic National Institutes of Occupational Health working within the field of isocyanate exposure and strategies for sampling and determination of isocyanates in workroom atmospheres. This viewpoint article summarizes the resolutions that were established at the 1st NORDNI consensus meeting arranged in Frøya, Norway, 31st August-2nd September, 2001. The consensus platform from the 1st NORDNI meeting was presented at the 4th International Symposium on Modern Principles of Air Monitoring, Lillehammer, Norway, 3-7 February, 2002.
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