| 1. |
- Haupt, Dan, et al.
(författare)
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Enantiomeric separations of remoxipride, propranolol, and trimipramine on CHIRAL-AGP using micellar chromatography and anionic additives
- 1993
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Ingår i: Chirality. - : Wiley. - 0899-0042 .- 1520-636X. ; 5:4, s. 224-228
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Tidskriftsartikel (refereegranskat)abstract
- The retentions and enantiomeric resolutions of remoxipride, propranolol, and trimipramine were studied using a CHIRAL-AGP column with micellar mobile phases and aliphatic, anionic additives. The retentions of the compounds, which in neat buffer solution were very high (k > 50), could be decreased to k < 10 by adding a mixture of Tween® 20 and heptanoic acid to the mobile phase. The presence of the aliphatic acid was essential in order to increase the enantiomeric selectivity. An efficiency enhancement was obtained by increasing the temperature. With a mobile phase composition optimized for the separation of remoxipride, the possibility of detecting levels of the enantiomeric impurity (R-remoxipride) down to 0.025% in the drug was demonstrated.
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| 2. |
- Haupt, Dan, et al.
(författare)
-
Separation of (R)- and (S)-naproxen using micellar chromatography and an alpha 1-acid-glycoprotein column : application for chiral monitoring in human liver microsomes by coupled-column chromatography
- 1992
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Ingår i: Journal of Biochemical and Biophysical Methods. - 0165-022X .- 1872-857X. ; 25:4, s. 273-284
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Tidskriftsartikel (refereegranskat)abstract
- A column-switching system for fast determination of (R)- and (S)-naproxen in liver microsomes has been developed. The centrifuged sample was injected directly onto a pre-column with octadecylcoated silica. The retained analytes were then directed to an alpha 1-AGP column using a mobile phase composed of phosphate buffer (pH 6.5), dimethylocytylamine (30 mM) and the nonionic surfactant, Tween 20 (40 g/l). The method gave high absolute recoveries and good repeatabilities: 99.6% (1.7% relative standard deviation) and 94.9% (2.4% R.S.D.) for the (R)- and (S)-naproxen, respectively. The use of a surfactant in combination with an aliphatic amine in the mobile phase involves reduced retention times with retained enantioselectivity. Furthermore, the presence of the surfactant makes it possible to inject biological samples directly into the chromatographic system.
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