On-line hydrogenation in GC-MS analysis of cyclic fatty acid monomers isolated from heated linseed oil
A simple on-line hydrogenation method in GC-MS analysis of unsaturated fatty acid esters is described. Using hydrogen as carrier gas, hydrogenation takes place in a capillary reactor connected to the outlet of the analytical column in the oven of the gas chromatograph. The reactor is a fused silica tube (60 cm×0.32 mm i.d.) coated with palladium acetylacetonate. Selective hydrogenation of olefinic bonds is achieved after a normal chromatographic run. Structural information (carbon-skeleton, double bond equivalents) can thus be deduced, and structural correlations between the saturated and unsaturated components can be obtained. Structures of cyclic fatty acid esters isolated from heated linseed oil were elucidated using this simple method which was found very useful for structural investigations on unsaturated compounds by GC-MS.
On-line hydrogenation of unsaturated and saturated sample components in capillary reactors coupled to either inlet or outlet of capillary columns
A special coupling piece for the connection of fused silica or softglass capillary hydrogenation reactors with capillary separation columns using a double oven GC instrument is described. The temperatures of reactor and column can be independently adjusted thereby. This system for on-line hydrogenation also includes two injectors to be used either before the reactor or before the column and a device for trapping the hydrogenated material inside the column. Platinum and palladium catalysts of various activities were investigated, aromatic hydrocarbons and compounds containing polar functional groups can be hydrogenated easily.
Methods and techniques of gas chromatography with glass capillary columns
SummaryAfter a general introduction on the advantages and special requirements of gas chromatography in glass capillaries the methods of preparing and testing thin film capillaries are described to an extent not convered in the authors' previous paper. By means of a series of chromatograms of typical artificial and genuine samples it is shown that the use of glass capillaries of variable length and with various stationary liquids does not present technical or methodical difficulties. With regard to temperature stability there is no difference in performance between packed and glass capillary columns. Moreover the preparation of glass capillary columns is easy, their separation efficiency is much better and the tailing behaviour is often superior in comparison with packed columns.