Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CHROMATOGRAPHY”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources
PubMed2003

Non-trivial temperature effects on the cation exchange chromatography and chelation ion chromatography of metal ions.

The effect of column temperature upon the retention of metal ions on sulfonated and mono-, di-, and amino-carboxylated cation exchange columns has been investigated. The retention of alkali, alkaline earth and transition metal ions on each of the above types of cation exchanger was studied over the temperature range 19-65 degrees C. A major difference between the behaviour of mono- and divalent metal ions was shown on each of the above stationary phases, with the monovalent alkali metals exhibiting clearly exothermic behaviour (a decrease in retention with increased temperature) under acidic eluent conditions and an apparent relationship between retention factor and the magnitude of the temperature effect. The effect of temperature upon alkaline earth metal ions was less defined, although strongly endothermic behaviour (increase in retention with temperature) could be seen on all stationary phases through correct choice of eluent. The transition metal ions studied showed endothermic behaviour on all four stationary phases, with the sulfonated column unexpectedly showing the largest increases in retention. The above behaviour can be partially explained through the dominance of the type of solute-stationary phase interaction governing retention. In several of the above columns, both ion-exchange and surface complexation interactions can occur, with the effects of temperature indicating which process dominates under specific eluent conditions.

Journal Article↗
PubMed1997

[Establishment of a coupling method of high performance liquid chromatography and capillary gas chromatography].

An on-line coupling system of normal phase microbore HPLC and capillary GC has been established, in which retention gap technique with on-column injection and partially concurrent solvent evaporation with early vapor exit were used. The conditions suitable for the coupling system of HPLC and CGC must be determined experimentally since the factors have to be adjusted with respect to solvent evaporation temperature and column inlet pressure etc. The suitable solvent evaporation temprature for the mobile phase used for this system, n-hexane, was about 70 degrees C. A temperature much, lower or higher than 70 degrees C will influence the GC analysis. In addition, solvent evaporation temperature and column inlet pressure are interacting, that is, higher solvent evaporation temperature needs higher inlet pressure. At the above evaporation temperature, the suitable inlet pressure for this system was about 0.2MPa. In order to minimize the extra-column effect on the LC peaks, thin transfer-line and connectors of zero-dead volume between LC column and GC column must be used. The separation and analysis of aromatics in a light diesel fuel was performed by using this system with 15cm x 2mm i.d. YGW (5microm) silica LC column and 60m x 0.25mm i.d. OV-101 GC column under the above conditions. The analytical results show that the system of on-line coupling of HPLC with CGC is a reliable analytical tool for microcomponents in complex mixtures, especially for those requiring sample preparation prior to GC.

English Abstract↗