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| 3. |
- Fridstrom, A, et al.
(författare)
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Dextran-modified polypropylene hollow fibers for use in capillary electrophoresis
- 1997
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Ingår i: JOURNAL OF MICROCOLUMN SEPARATIONS. - : JOHN WILEY & SONS INC. - 1040-7685. ; 9:1, s. 1-7
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Polypropylene hollow fibers with adsorbed phenyldextran as surface modification were shown to give useful and stable columns in capillary electrophoresis (CE). Two different sizes of phenyldextran, 40 and 500 KDa, and allyldextran, 150 and 2000 KDa, were
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| 4. |
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| 5. |
- Haglund, Peter, et al.
(författare)
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Shape selectivity : A key factor in comprehensive two-dimensional gas chromatographic analysis of toxic PCBs
- 2001
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Ingår i: Journal of Microcolumn Separations. - : Wiley. - 1040-7685 .- 1520-667X. ; 13:7, s. 306-311
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Tidskriftsartikel (refereegranskat)abstract
- A number of toxic planar PCBs, that is, PCB 77, 105, 118, 126, 156, and 169, were successfully separated from other PCB congeners present in technical PCB formulations using comprehensive GC×GC. The planar PCBs were selectively retained using a liquid crystal column, which was used as the first-dimension column. A short and narrow bore (0.25 m×0.1 mm) nonpolar 5%-phenyl-methylpoly-siloxane column was used as the second-dimension column. A longitudinally modulating cryogenic system (LMCS) was used to modulate the first-dimension signal. Since the planar PCBs elute from the first column at relatively high oven temperatures they were rapidly eluted from the second column. Altogether, this resulted in a significant peak sharpening, and a 20-fold increase in the signal-to-noise ratio, as compared to standard one-dimensional GC. This column set also seems to separate seven frequently measured congeners, that is, PCBs 28, 52, 101, 118, 138, 153, and 180, from other major PCB congeners.
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| 6. |
- Harju, Mikael, et al.
(författare)
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Comprehensive two-dimensional gas chromatography (GC x GC) of atropisomeric PCBs, combining a narrow bore beta-cyclodextrin column and a liquid crystal column
- 2001
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Ingår i: Journal of Microcolumn Separations. - : Wiley. - 1040-7685 .- 1520-667X. ; 13:7, s. 300-305
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Tidskriftsartikel (refereegranskat)abstract
- Peak assignment and quantification of PCBs in environmental samples is a time-consuming and costly process, and the analysis of atropisomeric PCBs is even more laborious and costly due to the elaborate analytical work involved. GC X GC can solve some of the problems entailed by increasing congener resolution and instrument sensitivity. In this study. a comprehensive two-dimensional gas chromatography (GC X GC) system was utilized with a combination of a permethylated beta -cyclodextrin column in the first dimension and a liquid crystal column in the second dimension. Using this system, in a single GC X GC run six out of nine studied atropisomeric PCBs (PCBs 91, 132, 135. 136, 149, and 176) can be resolved, and two (PCBs 84 and 174) can be partially separated from coeluting congeners in a mixture of 144 congeners (the most abundant congeners in technical PCBs). The chiral resolution (Rs) of the enantiomeric pairs ranged between 0.6 and 2.0, with PCB 132 having the highest resolution. Furthermore, the congers that (partially) coelute with enantiomers of PCBs 84, 95, and 174 have low abundance in technical PCB as well as in environmental samples. Thus, all of the nine target PCBs could be separated from significant interfering compounds in a single GC X GC run.
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| 8. |
- Juvancz, Z, et al.
(författare)
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Chiral analysis of metoprolol and its by-products by capillary electrophoresis
- 1999
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Ingår i: JOURNAL OF MICROCOLUMN SEPARATIONS. - : JOHN WILEY & SONS INC. - 1040-7685. ; 11:10, s. 716-722
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Tidskriftsartikel (refereegranskat)abstract
- The enantiomers of metoprolol, a frequently used beta-blocker, have different physiological effects, which makes their chiral separation necessary. The separation of the main product from its by-products and their chiral separation were also aims of this
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| 9. |
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| 10. |
- Juvancz, Z, et al.
(författare)
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Phosphated cyclodextrins as new acidic chiral additives for capillary electrophoresis
- 1997
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Ingår i: JOURNAL OF MICROCOLUMN SEPARATIONS. - : JOHN WILEY & SONS INC. - 1040-7685. ; 9:8, s. 581-589
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Tidskriftsartikel (refereegranskat)abstract
- The study describes the use of alpha,beta, and gamma phosphated cyclodextrins (CDs) for chiral separation by capillary electrophoresis (CE). A systematic study was performed to establish the effect of such variables as the type and concentration of chira
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| 11. |
- Koivisto, Pernilla, et al.
(författare)
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Determination of the free concentration of ropivacaine in plasma by packed capillary liquid chromatography : A comparison of ultrafiltration and microdialysis as sample preparation methods
- 2001
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Ingår i: Journal of Microcolumn Separations. - : Wiley. - 1040-7685 .- 1520-667X. ; 13:5, s. 197-201
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Tidskriftsartikel (refereegranskat)abstract
- In this study, ultrafiltration and microdialysis have been compared as sample preparation methods to separate the free fraction of ropivacaine from the protein bound in 150 μL plasma. A liquid chromatographic system with packed capillary columns (0.2 mm internal diameter) was used to enhance sensitivity when analyzing the small sample volumes obtained after the ultrafiltration and the microdialysis. The microdialysis was performed with probes of our own construction, and to save analysis time, the microdialysis sampling was coupled on-line to the liquid chromatographic system. The reduction of back pressure in the microdialysis outlet tube and in the injector was found to be essential. The free fraction obtained with each method was equivalent: both gave a free fraction of 6%.
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| 12. |
- Koivisto, P, et al.
(författare)
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Factors affecting the preparation of packed capillary columns in supercritical carbon dioxide media
- 1997
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Ingår i: JOURNAL OF MICROCOLUMN SEPARATIONS. - : JOHN WILEY & SONS INC. - 1040-7685. ; 9:2, s. 97-103
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Tidskriftsartikel (refereegranskat)abstract
- In this study, packed capillary columns were prepared using supercritical carbon dioxide as a packing carrier. A factorial design was used to examine the effect that four selected factors have on the packing performance. The investigated factors were: 1)
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| 14. |
- YUN, H, et al.
(författare)
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CHARCOAL POROUS LAYER OPEN-TUBULAR COLUMN GAS-CHROMATOGRAPHY FOR PERMANENT GAS-ANALYSIS
- 1995
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Ingår i: JOURNAL OF MICROCOLUMN SEPARATIONS. - : MICROSEPARATIONS INC. - 1040-7685. ; 7:3, s. 207-212
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Tidskriftsartikel (refereegranskat)abstract
- The preparation of charcoal porous layer open tabular (PLOT) columns, and their application to the separation of permanent gases and light hydrocarbons are reported. Two types of charcoal, coconut and darco charcoal, were used to prepare columns from fus
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