Search results for "COLUMN"
showing 10 items of 1301 documents
La coartada de los derechos
2000
Linz, 'cui prodest?'
2009
Resistencia crítica / 1
2008
Part 2. Synthesis, characterization and X-ray structure of a new enantiomerically pure bis-equatorial dirhodium(II) compound
2001
Abstract The UV irradiation of an acetone solution of Rh2(O2CCF3)4 and the chiral phosphane (1S, 2S, 5R)-(2-hydroxy-5-isopropenyl-2-methyl-cyclohexyl)diphenylphosphane, (+)PPh2(CHR*OH) leads to the formation of two diastereoisomeric bis-equatorial compounds of formula Rh2(μ-O2CCF3)2(η1-O2CCF3)2(η2-(+)PPh2(CHR*OH))2 P(+)2 and M(+)2 in a 1.5:1 ratio, respectively. Both compounds have been separated by standard column chromatography. The characterization of the enantiomer M(+)2 has been accomplished by X-ray crystallography. The molecular structure consists of an Rh2 4+ unit bridged by two trifluoroacetate ligands. The coordination of each metal center is fulfilled by one phosphine acting …
Corruptos y gloriosos / 1
2008
Política de Derechos Humanos
2000
Contra el imperialismo cultural
1977
Reseña en español de la ""I Conferencia internacional sobre el Imperialismo Cultural"". Argel, Argelia, 11-15 de octubre de 1977."
Is the thaw beginning?
2008
On-line analysis of carbonyl compounds with derivatization in aqueous extracts of atmospheric particulate PM10 by in-tube solid-phase microextraction…
2011
Abstract A new device for carbonyl compounds based on coupling on-line and miniaturizing both, sample pretreatment and chromatographic separation, is reported. Two capillary columns, a GC capillary column (95% methyl–5% phenyl substituted backbone, 70 cm × 0.32 mm i.d., 3 μm film thickness) in the injection valve for in-tube solid-phase microextraction (IT-SPME) and a Zorbax SB C18 (150 mm × 0.5 mm i.d., 5 μm particle diameter) LC capillary column were employed. Different combinations of IT-SPME and derivatization using 2,4-dinitrophenylhydrazine (DNPH) were examined for mixtures containing 15 carbonyl compounds (aliphatic, aromatic and unsaturated aldehydes and ketones). A screening analys…
On-line trace enrichment for the determination of ethacrynic acid in urine by liquid chromatography and column-switching
1993
Abstract A chromatographic method based on liquid chromatography (LC) using column-switching for the determination of ethacrynic acid in urine samples, is described. The proposed system uses a Hypersil ODS-C18, 30 μm (20 mm × 2.1 mm i.d.) pre-column for the pre-concentration and separation of ethacrynic acid from the biological matrix. Polar urinary compounds are removed by flushing the pre-column with purified water, and the enriched analyte is then switched in back-flush mode onto an HP-LiChrospher RP C18, 5 μm (125 × 4 mm i.d.) analytical column, where it is chromatographed using an acetonitrile-acetate buffer gradient elution. The UV detector was set at 275 nm. The recovery of drug was …