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DATA SHEET: CycloGraph(tm) Centrifugal Chromatography System
Features:
- Variable speed motor (100-1400 RPM)
- Integrated 4-watt UV lamp for hands-free viewing of the sample
- On/Off switches for the motor and UV lamp
- Adjustable plane angle setting of vessel(0-30 degrees)
- Ultra quiet & accurate low flow solvent pump (0-15ml/min)
- Compatible with all common chromatography solvents including acetic acid
- Easily detachable chamber for submersible cleaning
Introduction
The CycloGraph system is a centrifugally accelerated device for performing preparative chromatographic separations. The device spins a layer of adsorbent material coated as a flat ring on a glass backing. A solvent pump is used to apply the sample and mobile phase to the center of the spinning adsorbent ring. The centrifugal action accelerates the flow of the mobile phase through the adsorbent, separating the sample components as circular bands.
The mobile phase elutes continuously into a specially shaped collection channel inside the body of the instrument. Component bands are collected manually in test tubes or optionally by an automated fraction collector (not included). Separations occur quickly, usually within 20 minutes, versus the typical 90 to 120 minutes for preparative Thin Layer Chromatography (TLC) or Column Chromatography.
Principal of Operation
The stationary phase for the CycloGraph instrument is called a Rotor. A Rotor is similar to a preparative TLC plate but it is round instead of rectangular. The round glass support of a Rotor has a hole in the center so that it can be mounted on the motor of the CycloGraph. The motor will spin the Rotor at 720 RPM (see specifications). The adsorbent material of the Rotor is coated as a ring that does not extend into the center hole of the glass. This clear zone of glass at the center is where the sample and mobile phase will be applied.
The sample is applied first as a solution by way of the solvent pump or a hand held syringe. The spinning action of the Rotor will force the sample liquid to flow as a uniform round band on the inner edge of the adsorbent ring. The solvent pump is then switched to the mobile phase chosen to separate the components of the sample. The spinning action of the Rotor, and to a lesser degree the pump flow rate, provide the motive force of the mobile phase. The sample components will migrate through the Rotor adsorbent as circular bands and will have differing affinities for the adsorbent versus the mobile phase. This causes them to migrate at different rates affecting separation.
The circular bands eventually migrate to the outer edge of the adsorbent ring. The flowing mobile phase stream containing the component bands is ejected from the edge of the Rotor much like water from a rotating wet tire. A specially shaped collection channel around the outer perimeter of the Rotor collects the eluting mobile phase. The entire collection vessel is angled so that gravity drains the eluent to the exit port where it can be collected. The design of the vessel preserves the integrity of the sample bands so as to prevent remixing of the sample component bands.
Advantages
The CycloGraph centrifugal chromatography system combines the advantages of both preparative TLC and Column Chromatography. It delivers fast, efficient separations. Most separations occur in twenty minutes or less.
Fast separations are a result of the centrifugal action of the spinning Rotor driving the mobile phase through the adsorbent layer. The velocity of the mobile phase enables the use of smaller particle adsorbents. The Rotors for the CycloGraph use a 15 micron average particle adsorbent bed, similar to TLC. This smaller particle bed versus the 35-75 micron cut typical of low pressure column chromatography allows a higher degree of separation efficiency.
Centrifugal action combined with the use of a solvent pump to apply the mobile phase allow complete control of solvent velocity profile. Typical flow rates are in the range of approximately 2 - 3 ml/min per millimeter of adsorbent thickness. Tight bands mean eluted fractions can be collected in a minimum volume of solvent.
The solvent metering pump also makes the use of step gradients easy to perform with the CycloGraph. The inlet of the pump may be switched from a weak solvent to a more polar solvent during a run. This enables compounds with a wide range of polarities to be separated. Complex samples such as natural products are quickly separated into component classes.
Sweeping the polarity of the mobile phase from weak to strong makes it easy to reuse a Rotor for many sample separations. By concluding the run with a strong solvent, otherwise strongly adsorbed compounds will be flushed from the Rotor. This enables a Rotor to be reused for dozens of samples.
Separations on the CycloGraph scale easily and quickly. Rotors are available from 1 mm thick up to 8 mm thickness. For difficult cases, eluted components that are only partially resolved, can be cycled back onto the spinning Rotor. This effectively allows the chromatographer to increase "the length of the column" without the associated disadvantages.
Separations on the CycloGraph can be monitored as they happen with the built in UV254 lamp. Separated substances which absorb 254 nm light will be visible against the fluorescent green background of the Rotor. Optionally a UV366 source may be used to detect intrinsically fluorescent components.
Chemical integrity of sensitive sample components can be preserved even with the use of active silica gel adsorbents. Unlike TLC where the sample solvent is evaporated before chromatography, the sample introduced on CycloGraph need never be exposed to dry adsorbent. This minimizes the possibility of reaction of sample components on the active adsorbent surface. Further control of the atmosphere is possible by flushing the vessel with nitrogen gas during chromatography.
Prices and Accessories
CycloGraph Systems
| Description - 2009 Prices | Cat # | Price | |
|---|---|---|---|
| Standard CycloGraph System (includes) CycloGraph instrument, Solvent Pump with tubing, Test Dye, Instruction Manual, 1-Year warranty |
87-40 | $9,225.00 |  |
| Deluxe CycloGraph System (includes) All from the Standard System plus: Speed Monitor, Storage Chamber, Set of 4 Rotors (1 ea size) |
87-40d | $9,985.00 |  |
CycloGraph Optional Accessories
| Description - 2009 Prices | Cat # | Price | |
|---|---|---|---|
| FMI Low Flow Solvent Pump (0-30 mL/min) | 87-42 | $675.00 | |
| FMI Low Flow Solvent Pump (0-15 mL/min) - for Dry Solvent Applications | 87-42C | $750.00 | |
| CycloGraph Speed Monitor | 87-43 | $595.00 | |
| Rotor Storage/Desiccator Cabinet (photo below) | 50-05 | $275.00 | |
Silica Gel GF ROTORS & ROTOR Accessories - 2009 Prices
