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Application of the multicapillary columns (MCC) to be constituted by bundles of thin parallel capillaries whose inner surface is covered by film of a stationary liquid phase enables easily to achieve high speeds of separation in a gas chromatographic analysis. The MCC permit to cancel the restrictions inherent in other types of columns under conditions of the fast separation: 1) a big differential in pressure across the packed columns with slurry and 2) a low load capacity of the capillary columns of a small diameter.
Small length and diameter of capillaries of the multicapillary column allow carrying out the fast separations. Besides a great number of capillaries in the bundle enable to separate comparatively big volumes of samples that provides a high sensitivity of analyses.
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There are the following advantages of the multicapillary columns:
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such the columns permit to execute chromatographic analyses in a mode of the fast chromatography, namely, to execute them dozens of times faster than the usual packed columns;
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the multicapillary columns possess a high specific efficiency up to 12 – 14 thousand t.p./m and higher;
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the multicapillary columns keep the high efficiency in a very wide range of carrier gas flow rates;
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these columns are compatible with chromatographs, which work with the standard capillary and packed columns;
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the multicapillary column enables to separate a sample at a lower temperature than the other columns that is important when labile compounds are analyzed;
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the multicapillary column allows to increase the sensitivity of an analysis that is of importance in measuring trace contaminants;
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a unique peculiarity of the multicapillary columns with a capillary diameter 60 μm and up is possibility of their using both at big flow rates of a carrier gas (up to 1000 ml/min and more) and under moderate pressures at column inlets.
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Multichrom Ltd develops and produces the coiled and straight multicapillary columns of different dimension-types and with various immobilized stationary liquid phases, which are intended for solving multifarious applied analytical problems.
The straight and coiled multicapillary columns produced correspond to technical specifications (TU 548165985.001) of Multichrom Ltd. |
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Multi-channel Tubes |
Multi-channel tubes are a row material for production of the multicapillary columns. These tubes are manufactured from glass; the tube has an external protective cover; a multi-channel tube cross-section is a regular hexagon. The distance between facets of the tubes (the diameter of the tube farther) is equal to 2 - 6 mm; the channels (capillaries) of the tubes have a diameter of 20 to 80 μm and more; quantity of channels is from 919 to 4447.
Here you can see a cross-section of the multi-channel tube 6 mm in the diameter with 4447 capillaries of a diameter 60 μm. (Press for enlargement) ![[Image]](images/tr_right.gif)
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Straight Multicapillary Columns |
The straight multicapillary columns 40-250 mm long are mainly applied as a fast separating unit or as a precolumn in portable analytical gas analyzers. They can be also used in laboratory chromatographs; connecting them to an injector and detector is accomplished with the help of attached fittings with flexible capillaries. | | |
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Straight Multicapillary Columns in Protective Tubes |
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As the straight multicapillary columns are very fragile, for safe operation, especially, in the portable gas analyzers they are hermetically enclosed in protective stainless steel tubes. These multicapillary columns in protective tubes (columns in the casings) can be exploited at temperatures of no more than 210 0C. The columns 220 mm long are applied in the most of portable gas chromatographs. | |
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Coiled Multicapillary Columns |
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The coiled multicapillary columns are more suitable for operation in usual laboratory gas chromatographs (exploiting the capillary columns). The diameter of the column is 2 mm; diameter of capillaries is equal to 40 μm; quantity of capillaries is 919 – 1261. A length of the coiled column is 1 m; a diameter of coiling is 118 mm. The column efficiency is equal to 9000-14000 t. p. depending on a stationary phase used and a film thickness. For safe operation the coiled multicapillary columns are placed into special cassettes protecting them. | | |
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As the separation efficiency of the multicapillary columns depends on changes of the linear velocity of a carrier gas very weak, it is possible to exploit these columns in the mode of fast chromatography (time of an analysis cycle is no more than 2 s). In order to accomplish this mode of operation it is necessary to use fast acting injectors, detectors and providing electronic devices (response time is about 1-2 ms).
The chromatogram* below demonstrates a fast separation of a mixture of aromatic compounds on a straight multicapillary column 250 mm long at a carrier gas (helium) linear velocity 2.1 m/s. Peaks: 1 – propylene; 2 – benzene; 3 – toluene; 4 – m-xylene; 5 – o-xylene.
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*For reviewing the chromatogram in real-time functions: “Show pictures” and “Play animation” on your Internet browser must be switched on.
For more details about performances of multicapillary columns
Assortment of multicapillary columns
Catalogue: multicapillary columns
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