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Existing methods for preparing frits in packed fused silica capillaries as used for electrochromatography and micro HPLC are not applicable to all silica based packing materials and involve a high thermal stress for both the stationary phase and the fused silica tubing including the polyimide coating. A new procedure for the production of such on-column frits under mild conditions by a sol-gel type reaction of polydimethoxysiloxane (PDMOS) is described in this paper. Reaction conditions were established for optimum mechanical stability and high permeability of the frits. Frits produced in this manner showed no noticeable effect on the overall efficiency.

A dry-packing method has been developed which enables the preparation of packed capillary columns for micro HPLC from 250 μm i.d. tubing and 5 μm packing materials. Pressurized gases, such as hydrogen and argon, were used to transport the packing media, and ethanol or methanol were used as discharge agents. By changing the gas pressure, the packing density could be easily adjusted. It was found that, within experimental limits, the higher the packing density, the greater the column efficiency. Comparison between dry- and slurrypacked columns showed that the former had greatly improved stability; the efficiency of dry-packed columns was about the same as, or even better than, that obtained by slurry-packing.

In view of the importance of cyclodextrins in various pharmaceutical areas, methods for their determination in plasma are necessary for pharmacokinetic studies. Cyclodextrins show almost no UV absorption. This paper describes indirect detection of cyclodextrins in micro-HPLC

Infrared monitoring was accomplished in reversed phase HPLC on using deuterated solvents. The end of a micro HPLC column was flattend and used as a flow cell for on-column IR detection. Detection of alkylbenzenes and oil-soluble vitamins which were separeted on ODS packing with CD3CN/D2O and CD3OD, respectively, was performed at 2940 cm−1.

Utilisation des techniques de spectrometrie IR a transformee de Fourier, de la chromatographie en couche mince avec de l'alumine et de la chromatographie HPLC en phase inverse afin d'identifier des composes de melanges complexes

High-performance micro packed fused-silica and open-tubular glass capillary columns were prepared and applied to separations of complex mixtures. Solvent-gradient elution proved quite useful for the separation of solutes with wide polarity. Instruments and some applications are described.

A miniaturized continuous gradient elution system with variable gradient profile was designed. A retention time reproducibility below 1% was achieved. The system was applied to the separation of phenolic compounds with a wide range of polarities.

A micro high-performance liquid chromatographic (micro-HPLC) method was developed for the determination of purpurea glycoside A, purpurea glycoside B, and glucogitaloxin in Digitalis purpurea leaves. The extract of dry leaf powder was applied to a Sep-Pak silica cartridge followed by preparative thin-layer chromatography prior to micro-HPLC analysis. The analysis was performed on an ODS micro column, using acetonitrile-methanol-water (21:20:45) and ultraviolet detection (220 nm). The amounts of purpurea glycoside A, purpurea glycoside B, and glucogitaloxin per 100 mg of dry leaf powder were estimated to be 52.6, 50.7, and 108.6 μg, respectively.

Application de la methode du titre a l'analyse des hydrocarbures paraffiniques et aromatiques d'une fraction essence

The possibility of high-speed micro-HPLC has been investigated using a short micro-column (35 mm × 0.5 mm i.d.) packed with 3 μm ODS particle. The results indicate that this approach has considerable potential for good separations with short analysis time. A typical example shows only three minutes is required with a plate count of 3,800 to separate seven PAHs.