Bottletop Burette Operating Tips

Bottletop burettes such as the Contiburette® models offered by CAT Scientific are often preferred over glass tube volumetric burettes and pipettes because of their ease of operation and improved accuracy.  Moreover they greatly reduce the incidents of operator error and are much easier to clean.

Like all precision lab instruments bottle top burets work best when properly installed and maintained.  That’s why they are shipped with an in-depth instruction manual.  We at CAT Scientific cannot stress too strongly the need to read these instructions.  This blog post touches on certain of the operational procedures, and we’ll follow on from time to time with additional operating suggestions.

It might be a good idea to let you know when not to use this precision liquid handling equipment.  While they are designed to handle a number of different reagents the list excludes

  • liquids attacking the unit’s Al2O3 and ETFE wetted parts
  • suspensions such as charcoal that may clog or damage the instrument
  • strongly crystallizing solutions, concentrated acids and bases
  • non-polar solvents that will swell ETFE, and
  • highly flammable materials such as carbon disulphide

While the Contiburette is by nature stable when the reagent bottle is full it should be placed on a level solid surface.  Ambient conditions such as temperature and humidity impact performance and must be accommodated as outlined in the instruction manual.

Some Bottle-top Burette Basics

As a safety precaution you must exercise extreme care to avoid spills when attaching the burette mechanism to the reagent bottle.

Because reagent bottles vary in capacity and configuration first select the proper adapter to connect your burette to the bottle.  Two adapters are provided with CAT bottletop burettes and other sizes are available.

You’ll have to tailor the suction tube length accordingly.  Firmly push the tube over the suction fitting at the base of the burette mechanism to eliminate the potential of air leakage and resulting inaccurate measurements.  Determine the appropriate tube length and cut the bottom at an angle to avoid suction blockage.

Hold the grey control and dispensing mechanism housing when attaching the burette to the reagent bottle, making certain that the bottle contents label is clearly visible below the burette operating panel.  Carry the unit by grasping the neck of the bottle and with the other hand support the bottle at its base.

Install the discharge tube by pushing it gently into the Contiburette mechanism as far as it will go and orient the tip to the container receiving the dispensed liquid.

Run a test to be certain there are no leaks at any of the fittings.  Do this by placing a beaker or flask under the discharge tube and operate the system in the manual mode until the liquid in the tube is clear of air bubbles.

Again use caution to avoid contact with the reagent, or allowing it to spill on and possibly damage lab materials.

You’re now ready to program your equipment for the measuring tasks at hand.

A Caution on Calibration

While this post looks at operating tips another factor affecting the accuracy of a bottletop burette is its calibration. CAT Contiburettes are factory adjusted using water before delivery.  It’s always a good practice to recalibrate the burette after a period of use or if you are dispensing liquids with densities significantly different that water.

Detailed instructions on calibration are contained in the operator’s manual, but you’ll find a primer in our post on calibrating a bottletop burette.

And as always feel free to ask us a question on any aspect of these precision liquid dispensing and measuring devices.

Bob Wilcox

Bob Wilcox has represented CAT Scientific’s family of homogenizers, magnetic stirrers, liquid handling and related laboratory equipment since 2002 when Staufen, Germany-based CAT Ingenieurbüro M. Zipperer GMbH established operations in North America. Bob oversees CAT Scientific laboratory apparatus sales and service organization from the company’s headquarters in Paso Robles, CA. He also is in charge of the parent company’s line of JetCat jet turbines, turboprop, and helicopter power plants for hobbyists’ radio controlled fixed wing and helicopter model aircraft. -- Earlier in Bob’s career he was involved in visual and special effects as well as camera and electronics supervisory responsibilities for the motion picture and television industry.

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