Quantum Northwest Inc.

TLC 42™ Dual Temperature-Controlled Cuvette Holders for Sample and Reference The TLC 42™ provides two independently controlled cuvette holders, one for the sample and the other for the reference. It is used in a dual beam UV/Vis spectrophotometer. Each cuvette holder provides precision temperature control from well below zero to 105 °C. Each cuvette holder has variable speed magnetic stirring and a dry gas purge to minimize condensation on the cuvette surfaces when working at low temperature. The TLC 42 is provided with a matched and calibrated TC 225 Temperature Controller.

TLC 42™ for the Cary 100 UV/Vis spectrophotometer	Breakaway view of a TLC 42™ for a dual beam spectrophotometer

• Rapid, precise Peltier control over a wide range of temperatures
• Independent control of the sample and reference temperatures
• Variable speed magnetic stirring
• Dry gas purge
• Optional remote computer control
• TC 225 temperature-controller included

Description
The TLC 42 has two 50 x 50-mm square towers, spaced to place the cuvettes in the sample and reference beams of a dual beam spectrophotometer. The height of the towers is cut to fit the dimensions required by the spectrometer. Metal cores in each tower hold the cuvettes to regulate their temperature, and plastic housing surround each core, providing thermal insulation. The cuvette holders of the TLC 42 have optical ports on opposite sides of the tower to permit the passage of light through for the absorbance measurement. Each port is 10 x 10 mm in size, a size adequate to accommodate the light beams for nearly all spectrophotometers. The temperature of each TLC 42 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 each TEC. For magnetic stirring, a magnet is located directly under each cuvette and is rotated using a small, precision, Swiss motor. If needed, a flow of dry gas may be passed through the base of each tower for partial temperature equilibration and then directed into the optical ports next to the cuvette surfaces, thus minimizing condensation. The TLC 42 includes a matched and calibrated TC 225 Dual Temperature Controller.

Cuvette Size and Types
Each insulated temperature-controlled tower of the TLC 40 holds a standard 10 x 10 mm path length square cuvette. To maximize thermal contact, the cuvette is held into one corner of a tower by a metal spring clip. In its standard configuration, the TLC 40 is designed for a “z-height” of 8.5. Thus, the optical center line, or middle of the optical port, is 8.5 mm above the bottom surface of the cuvette. This is a convenient dimension because it minimizes the sample size in most cuvettes. It is also a standard height for microcuvettes and flow cells.

Special Options

APOST-1, Accessory Post	An optional accessory post may be inserted in the top of either tower of the TLC 42, with clips to hold tubes, probes or other hardware for special measurements.
SER 2.3, Serial Control	Optional software, the SER 2.3 package, is available to operate the controller remotely from your computer, allowing complex functionality, including temperature ramping.
BATH 100, Water Circulating Pump	The TLC 42 requires a small flow of water to pass through the heat exchangers below each TEC. To provide such a flow, you may purchase the optional BATH 100, which consists of a submersible pump, a plastic bucket and the necessary tubing and fittings.
WJ-40, Windowed Jacket	The optional WJ-40 Windowed Jacket is available for work at temperature extremes. The WJ-40 provides additional insulation and windows covering the two optical ports of either tower of the TLC 42. When using a dry gas purge, the windows enclose the gas to help prevent condensation on the cuvette.
TLC 42/Z15, 15 mm z-height option	For additional cost, most versions of the TLC 40 may be made for a z-height of 15 mm instead of the standard 8.5 mm. 15 mm is also a common z-height for microcuvettes and flow cells. In many cases it is also possible to make other custom z-heights.
TLC 42/E, Extreme Temperature Option	The highest temperature setting for the TLC 42 is normally 105 °C. A special version of the TLC 42 can be used for limited times at temperatures as high as 150 °C. With special care, this extreme temperature version may also be used below -40 °C (see Temperature Range).

Mounting Requirements
As you can see in the page on Aftermarket Cuvette Holders, Quantum Northwest has the necessary knowledge to make versions of the TLC 42 for most common commercial dual-beam spectrophotometers. 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 TLC 42 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
Each cuvette holder of the TLC 42 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.

Availability
You will need to specify the spectrometer in which the TLC 42 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 whether you would like the WJ-40 Windowed Jacket for work at extreme temperatures. A TLC 42 can usually be shipped in two to three weeks after receipt of order. 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.

Quantum Northwest provides temperature-controlled cuvette holders and photoacoustic instrumentation