• Description
• OEM Platforms
• Modular Units

Description
Separation scientists can face extremely challenging separations of complex mixtures that cannot be resolved in a single chromatographic step. Multidimensional chromatography uses coupled columns and column switching to resolve complex mixtures that cannot be separated using a single column. Multidimensional chromatography allows resolution of complex mixtures by using different columns in a series that employ different separation mechanisms. A primary column connects to two or more secondary columns using a selector platform. Fractions from the first column can selectively transfer to the other columns for further separation.

Automation of the multidimensional chromatography process incorporates a combination of injection and column switching platforms. Automation dramatically cuts time, saves cost, and increases productivity while improving analytical results. Common applications for which multidimensional chromatography is beneficial are:

• Proteins and Polypeptides
• Drug Isolation from Urine and Plasma
• Polysaccharides
• Chiral Recognition
• Homopolymers, Oligomers, Copolymers
• Surfactants
• Polycylic Aromatic Hydrocarbons
• DNA Fragments

The following examples illustrate using one, two, three, or more columns in series to obtain further separations of certain components of complex samples. The schemes show the complexity of multiple separation mechanisms while providing automated systems using Rheodyne's family of Fluid Modules.

One Additional Column: In the following example, two pumps, one detector, a Two-Position, Six-Port platform used as an injection platform, and a Two-Position, Ten-Port platform used as a selection platform, are in-line. Peaks from the first separation mechanism (Column 1) transfer into a trapping loop in the Two-Position, Ten-Port using Pump A (see Position A). The Two-Position, Ten-Port switches and Pump B moves the trapped peak from the trapping loop onto Column 2 (see Position B). After allowing time for the trapped peak to move onto Column 2, the Two-Position, Ten-Port switches again and the second dimension separation (Column 2) is done using Pump B. Column 1 regenerates using Pump A.

Alternative Columns: In the next example, one pump, one detector, a Two-Position, Ten-Port injection platform, and a Two Channel Selector with By-Pass are in-line. Peaks from the first separation mechanism (Column 1) are monitored by pumping through the internal by-pass position (white groove) of the Two Channel Selector with By-pass. When the peak of interest elutes from Column 1, it can then load directly onto Column 2A (see Position A) or 2B (not shown) by switching the Two Channel Selector with By-pass Different solvents can then be selected for the pump and washed through the Two Channel Selector with By-pass (see Position B). Column 1 is simultaneously by-passed by switching the position of the Two-Position, Ten-Port. A second dimension separation can perform on either Column 2A or 2B. This configuration eliminates the need for extra pumps or detectors but Column 1 becomes idle while the sample elutes from Columns 2A or 2B.

In the third example below, two pumps, a UV detector, a mass spectrometer, a Two-Position, Six-Port injection platform, and another Two-Position, Six-Port column selection platform are in-line. Peaks from the first separation mechanism (Column 1) can be monitored continuously using Pump A and the UV detector (see Position A). When the peak of interest elutes from Column 1, the Two-Position, Six-Port switches (see Position B) to allow direct loading and trapping on Column 2. The Two-Position, Six-Port switches again (returns to the position in Position A) to backflush the compounds of interest from Column 2 onto Column 3 using Pump B. Separation on Column 3 proceeds using Pump B to a mass spectrometer.

OEM Platforms
Rheodyne offers a variety of different platforms for your multidimensional chromatographic needs. The table below contains a list of current valves for this application including direct links to literature for more detailed information. If you do not see the valve that best suits your application, please contact Rheodyne to discuss your multidimensional chromatographic needs.

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Modular Units
Rheodyne manufactures a variety of self-contained, electrically operated modular units for multidimensional chromatographic applications. The following table lists modular units designed for these applications. Links to available specification sheets and a product line bulletin provide detailed information.

• Contact Rheodyne for assistance in locating a unit that meets your needs.
• Click here for a list of Distributors.

Note. You will need Acrobat Reader to view these files (click to open or right-click and select "Save Target As" to download).