Liquid gas techniques for GC trace analysis

Liquid gases (LG), i.e. low boiling compounds with vapor pressures below 5 bar at room temperature, are introduced as solvents for trace analyses. A system for preparin, diluting and handling LG solutions safely and conveniently in 5 to 500 μl amounts was developed as well as a syringe for direct injection of μl-LG samples into capillary GC. Even technical grade LG are of high purity. GC/FID of LG solutions (starting at −60°C) allows the separation of volatile traces from the solvent peak: e.g., dichloromethane can be measured in the picogram range.

High Pressure Liquid Chromatographic Analysis of Barbiturates in the Picomole Range by Fluorometry of Their DANS-Derivatives

�ber die Kupferelektrolyse

Die schlechte Reproduzierbarkeit bei der elektrolytischen Kupferabscheidung wird durch schwankende Konzentrationen an Chloridverunreinigungen verursacht. Bromidionen bilden auf der Kathode eine Adsorptionsschicht, die die Abscheidung erleichtert. Harnstoffzusatze sind wirkungslos.

Fluorescence labelling of organic acidic compounds with 4-bromomethyl-7-methoxycoumarin (Br-Mmc)

4-Bromomethyl-7-methoxycoumarin (Br-Mmc) is introduced as a fluorescence marker for aromatic and heterocyclic acids. To investigate the applicability of this method on substances of different chemical classes, screening experiments with 110 compounds were carried out using a microrefluxer. Most aromatic and heterocyclic monocarboxylic acids gave Mmc-esters which are fluorescent on thin-layer plates, like the Mmc-esters of fatty acids, which have been previously investigated. Strong acids, alcohols, amides and most amines did not react, whereas certain cyclic amines such as piperidine gave strongly fluorescent derivatives. Mmc-phenyl ethers shows only weak fluorescence. A new standard proced…

Identification and quantitation of trace amounts of barbiturates with glass capillary gas chromatography

Pre-chromatographic reactions are no longer a necessary evil. Equipment such as the microrefluxer now allows reproducible 7-μl-reactions to be carried out in a short time. Thus multiple derivatisations can be used together with glass capillary GC for routine identifications. The method has been succesfully applied to barbiturates. Retention data of their methyl-, allyl- and benzyl-derivatives are given. Quantitative blood level determinations are briefly discussed.

High-performance liquid chromatographic separation of esters of 4-hydroxymethyl-7-methoxy-coumarin