Category Archives: Model 2100C

Resetting the Thermal Safety Switch / Priming the TCS Pump

REASON:  The circulator is not turning on due to thermal switch reset. This occurs when the TCS pump is not primed properly.

PRE-REQUISITE:  Service Engineer or person performing this service must have proper training in servicing the instrument.


Step 1.  Turn off the TCS and unplug from the AC outlet prior to resetting the thermal switch.

NotesMake sure that the TCS has had time to cool down prior to resetting the thermal safety switch. This can take up to 10 to 20 minutes.

Step 2.  On the back of the TCS there is a small access hole where the thermal safety switch is located (As shown below). Using a non-metallic tool or the end of a pen or pencil, reset the thermal safety switch by depressing the button. You should feel or hear a click indicating that the switch has been reset.

Thermal Safety Reset

Step 3.  Once the thermal safety switch has been reset, make sure the TCS has been properly primed or the thermal safety switch will trip again. Please see Priming the TCS Pump steps below. Turn on the unit and enable the heater.

NotesInformation about resetting the thermal safety switch can be found on page 3-14 in the 2100C Operation Manual.

NotesInformation about priming the pump can be found on page 2-6 in the 2100C Operation Manual and on page 2-8 of the EVO 6300 Operation Manual.


Step 1.  Attach a 24 inches (61 cm) long x ½ inch (13mm) ID drain tubing to drain valve.

Step 2.  Raise the drain tubing to vertical position as shown. Drain valve should be tilted up.

To Prime Pump (TCS-0200C)

Step 3.  Cover the end of the tubing with your thumb and open the drain valve. Slowly lower the tubing while slowly opening the end of the tubing allowing water to fill up as much of the tubing. Once filled, close again the end of the tubing with your thumb and raise the tubing. Uncover the end of tubing to force water in to the pump inlet. Perform this step at least two to three times. Turn on the TCS circulator and observe that air has been purged from the pump indicating that the pump was primed correctly. If it does not, repeat step 2 and 3 until all the air is purged from the pump.

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Filed under Model 2100C, TCS-0200C

Connecting a Distek dissolution system to the Evolution 4300

When connecting a Distek dissolution system to the Evolution 4300 syringe-pump dissolution autosampler, you will need to connect an RS-485 cable between the two systems to allow for electronic control of the dissolution unit from the autosampler.

Depending on the type of dissolution system that is being utilized with the Evolution 4300 autosampler, the specific RS-485 cable needed will be different (the connecting ends are different).

If you have our new symphony 7100 or Model 2500, you will need part number 2700-0162 (RS-485 Cable for 4300 Sampler to 7100 and 2500).

If you are using an Evolution 6100, Evolution 6300 or 2100C, you will need part number 2400-0004 (RS-485 Cable for 4300 Sampler to 2100C, 6100, and 6300).

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Filed under Evolution 4300, Evolution 6100, Evolution 6300, Model 2100C, Model 2500, Symphony 7100

Model 2500 vs. 2100C

Model 2500

During a recent Model 2500 presentation we were asked the following:


“Besides the discontinuation of the 2100C, what additional justification would you recommend for us in replacing a 2100C with the new 2500?”


 Added Control and Compliance

  • The Audit Trail records the last 50 changes made to a method, should an investigation occur.
  • Three user access levels limit user abilities and permissions.
  • The 100 most recent test reports are saved, allowing them to be reviewed at a later date if necessary.

 Additional Time-Savings

  • The ability to store methods allows users to quickly select an entered method and run it without re-entering parameters.
  • TCS wake timer allows the bath to be pre-heated and ready for use prior to arrival of laboratory staff.

 Ease of Use

  • Intuitive touch-screen interface simplifies entry of key parameters (RPM/Temperature/Time) from one screen.
  • Firmware updates can be easily emailed or downloaded from the internet to a USB Key eliminating the replacement of firmware chips.

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Filed under Bath-Based, Model 2100C, TCS-0500

Intrinsic Dissolution


The intrinsic dissolution rate is defined as the dissolution rate of pure substances under the condition of constant surface area, agitation-stirring speed, pH and ionic-strength of the dissolution medium. 

The knowledge of intrinsic dissolution rate is vital in screening new drug candidates as it can help optimize the physiological effectiveness of new dosage forms. Distek has improved the performance and reliability of the rotating cylinder or “wood apparatus” with the paddle over stationary disk intrinsic apparatus. This is available in two configurations; standard for use with 1L vessel and mini for use with 100/200 ml vessels. The Distek design avoids the formation of air bubbles on the surface of the product and eliminates the potential of product “slippage” as can be the case with the wood apparatus.

 The Distek standard and mini intrinsic apparatus consists of steel punch, die, and base plate (fig. A).

Figure A

Test material is placed in the 0.8 cm diameter die cavity (optional cavity sizes are available) and the punch is inserted. The punch, die and press plate are placed in a laboratory press and kept under 2000 psi for 4-5 minutes. The press plate is disconnected from the die to expose a compact pellet of .5 cm2 surface area.

A Viton gasket is placed around the threaded shoulder of the die and a polypropylene plastic cap is screwed onto the threads. The assembly is then immersed, pellet side up, in the bottom of a flat dissolution vessel containing 900ml of dissolution medium at 37C. The paddle blade is positioned 6mm above the surface of the pellet and rotated at 50 rpm.

See USP 30-NF 25 General Chapter <1087> page 531 for more details.


Filed under Bath-Based, Bathless, Evolution 6100, Evolution 6300, Model 2100C

Embedded Temperature Sensor in Stirring Shaft

The embedded temperature sensor inside each of the hollow stirring shafts allow the EVOLUTION Series to continuously control, monitor, and record the temperatures of each individual vessel throughout the entire Dissolution test. Located inside and at the bottom most position of the shaft (red arrow below), the temperature sensors are able to continuously monitor the temperature of the media. Without the use of an external thermometer it eliminates any associated hydrodynamic effects.  The EVO 6100 and EVO 6300 are the only dissolution systems on the market with this capability.

The shafts of the EVO 6100 and EVO 6300 are designed for 100% assurance that the medium temperature is maintained throughout the entire test.  Also, it eliminates the need to remove the shaft when changing between apparatus 1 (baskets) and apparatus 2 (paddles) thanks to the use of detachable stirring elements and the height adjustment block.

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Filed under Evolution 6300, Model 2100C, Parts & Accessories

Cipher Software

Cipher instrument control software is a Windows based application designed and developed by Distek to remotely access and control our dissolution equipment.*

 Cipher can be installed locally or networked providing full access to any Distek dissolution bath and autosampler from any appropriately connected PC running the application. Cipher allows the user to create and run methods, monitor instrument status, generate reports, and control users and manager logins.  Cipher also offers the flexibility to set the level of security appropriate for your laboratory.  When enabling all the security features and combined with the appropriate internally developed policies, Cipher will meet 21 CFR part 11 compliance.

 * Cipher currently controls the Model 2100C, EVO 6100, 6300, and 4300

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Filed under Cipher Software, Evolution 4300, Evolution 6100, Evolution 6300, Model 2100C


Distek’s 2100C water bath-based dissolution system (pictured below) is known for being durable and user-friendly.  However, your clients may not be aware of the versatility and customization that the 2100C offers.  When configured at the time of the order, the Distek 2100C has the ability to support up to eight 2L vessels or four 4L vessels.  Also, with the quad stir (pictured below) or the single station small volume kit the 2100C can support 6 to 24 positions at 100ml or 200ml.

 Please note that an existing system cannot be upgraded to 2L/4L capabilities


Quad Stir

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Filed under Model 2100C