SummaryThe results of investigations with ion pair chromatography on RPp, RP8 and RP18 thin layers are described. Heptane sulphonic acid is used as ion pair former. The best results are achieved on RP18-layers with the counter ion in the mobile phase.

SummaryThe results of ion-pair chromatography with UV-absorbing counterions are described. Hydroxynaphthalenesulfonic acids are used as ion pair formers, and alkaloids as test samples. The separationsare performed on silanized silica gel from Merck and KCIBF plates from Whatman. The influence of the counterion on the Rf-value is demonstrated. Some alkaloids exhibit characteristic fluorescence as ion pairs.

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The chromatographic behavior of some hydrocarbons and some of their nitro derivates after preconditioning with solvent vapors has been investigated. After preloading with cyclohexane or hexane an improved separation of some sample pairs is observed. Furthermore, inversion of Rf values takes place. The preloading of the reversed-phase plates permits utilization of mobile phase with higherwater content, thus leading to a significant shortening of developing time.

Short Communications 0250glass wool or beads in the injector improved reproducibility for injections of hydrocarbon or column performance standards, but also promoted decomposition of the more unstable carbamates. With the injector design employed, i.e., no glass wool or beads, decomposition was negligible (as measured with the FID) forall of the compounds examined except oxamyl.It is clear that most N-methylcarbamates and some related thiocarbarnates and oxirnes can be chrornatographed with high efficiency and without thermal decomposition under the chromatographic conditions described, and that limits of detection with the NP-TSD are compatible with levels anticipated in environmental samples. The application of this technique to environmental samples is in progress.