| • Rapid, precise Peltier control over a wide range of temperatures • Carriages available for common cuvette types • Variable speed magnetic stirring if needed • Equilibrated nitrogen gas purge • Optional remote computer control • Optional built-in windows for stable thermal control • Compact size to fit most CD spectrometers • TC 125 temperature-controller included Description Since there are several kinds of CD cuvettes that are commonly used, the CD 250 controls the temperature of a metal cuvette carriage that holds the cuvette. The carriage screws down firmly into a temperature-controlled base. Optional windows at each side of the cuvette carriage enclose and control the environment around the cuvette, making it possible to precisely control the temperature of short path length cells. Nitrogen may be passed through a heat exchanger and directed within this chamber to speed equilibration and eliminate oxygen around the cuvette. Magnetic stirring may be used in square cuvettes or other cuvettes with adequate volume to hold a stir bar, thus minimizing temperature gradients in the cuvette. The temperature of the CD 250 tower is controlled by a thermoelectric cooler (TEC), a device using the Peltier principle. The TEC pumps heat into or out of the tower. For heat removal, a small flow of water passes through a heat exchanger under the TEC. The CD 250 includes a matched and calibrated TLC 125 Temperature Controller. Cuvette Size and Types
Special Options
Mounting Requirements As you can see in the page on Aftermarket Cuvette Holders, Quantum Northwest has the necessary knowledge to make versions of the CD 250 for several commercial circular dichroism instruments. If you do not find your instrument in the list, please contact us anyway. With a little help on dimensions and the configuration of your spectrometer sample compartment, we can usually make a custom cuvette holder for a price comparable to that of one of our normal products. We are happy to do this, because it helps us learn about different instruments. To make a version of the CD 250 for a spectrophotometer, we must know some basic information about the floor plate of the sample compartment and how we must make a base plate that will mount in place. We also must know the height of the optical center line above the floor of the sample compartment. An easy way to determine this basic information for a new spectrophotometer is to measure an existing non-regulated cuvette holder. Utilities for the cuvette holder include two tubes for water (or other coolant), one tube for dry gas, and an electrical cable. These must pass out of the sample compartment in a manner that does not disrupt the measurement. Suitable methods for getting the utilities out of the sample compartment have been found for most common spectrophotometers, but we may require assistance and suggestions for new instruments. Performance Using a 10 x 10 mm path length square cuvette, the CD 250 has temperature performance very similar to that of the TLC 50. The temperature of the holder changes rapidly and may be maintained at ±0.02 °C. However, when working with short path length cylindrical cells, where the thermal path from the sample holder to the sample is long, equilibration with be relatively slow. Availability You will need to specify the spectrometer in which the CD 250 will be used. You will also need to tell us if you want a special option such as a different z-height or a high temperature option. Tell us if you would like a BATH 100 water circulator and the SER 2.3 software package. Most configurations of the CD 250 can be shipped in two to three weeks. New configurations require getting necessary dimensions and preparing designs will, of course, also require additional time for design. Please contact us with your questions or to request a quotation. |
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