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Mark Levi


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The Importance of Validating Burettes on an Automatic Titrator

By Mark Levi on Mon, Jun 26, 2023 @ 03:38 PM

This might sound a bit technical but has significant importance in the world of chemistry: validating burettes on an automatic titrator.

For those who are not familiar with burettes, they are glass tubes used in laboratories to measure the volume of liquid dispensed. They are essential in titration, a process of chemical analysis used to determine the concentration of an unknown solution by reacting it with a known solution.

An automatic titrator, on the other hand, is a device used to automate the titration process. It reduces human error, increases precision, and saves time. However, to ensure accurate results, it is crucial to validate the burettes used in the titrator.IMG-0807-1

Now, let me get personal and share a story. I once worked in a lab where we had a faulty burette that was not calibrated correctly. We did not realize it until we compared our results with another lab, and they were different. We had to redo all our tests, causing a significant delay in our research. It taught me the importance of validating instruments before conducting any experiments.

To validate a burette, we need to check its accuracy by measuring the volume of liquid it dispenses. We can use a standard solution of a known concentration to verify the accuracy and precision of the burette. This process ensures that the titration results are reliable and trustworthy.

Here's a random fact related to the topic. Did you know that the burette was invented by a French chemist named Francois Antoine Henri Descroizilles in 1824?

To sum this all up,  validating burettes on an automatic titrator is crucial to ensure accurate results in chemical analysis. It may seem like a small step, but it can make a significant difference in research and experiments. So, let's not overlook the importance of this process and always validate our instruments before conducting any tests.

P.S, Check out our Burette Validation & Repair Service. 

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Karl Fischer Titrator not finding all of the moisture you expected?

By Mark Levi on Sun, Jan 08, 2012 @ 03:01 PM

Aquapal IIIIf your operating a dual-reagent Karl Fisher Titrator and your getting lower than expected moisture results you may want to check a few things.  First, make sure your analytical balance or specific gravity (if you use it) calculation is not the problem. Next, focus your attention on the reagents.

    Find out more about the Aquapal III

Reagents can cause problems if they are not being replaced often enough.

With a dual-reagent setup the operator places anolyte into the main vessel (75mL to 150mL of anolyte solution depending on the vessel size) and catholyte into the generator electrode (5mL of catholyte solution).

Now for some reason, most operators focus their attention primarily on the anolyte reagent and take great care in monitoring the condition and level of the anolyte. Unfortunately their is a tendency to forget about the catholyte. I say unfortunately because it is this oversight that can cause the problem.

Before I tell you the reason for the problem it’s helpful to know some useful information about the reagents ability to measure moisture. A typical vessel can hold 100mL of anolyte. 100mL of anolyte (Coulomat A, Coulomat AG, Coulomat AG-H) can measure 1,000,000 micro grams of water. Yes, 1 million micrograms of water!. Conversely, the pre-measured 5mL ampules of catholyte solution (Coulomat CG) that goes into the generator electrode has the ability to only measure 300,000 micro grams of water per 5mL charge. Do you see it?  Do you see the connection?

There is a 3 to 1 relationship of the catholyte to anolyte!

Yes, you should be replacing the catholyte 3 times per 1 charge of the vessel. Or put another way, change the catholyte 3 times as often as you change the anolyte.

Find more Coulometric Karl Fischer Titrator information


Now, back to the problem and the answer. If your not replacing the catholyte often enough, the catholyte will actually begin to convert and form a salt by-product. This “salt by-product” can then form and become deposited down around the frit at the bottom of the generator electrode (AKA inner buret) and clog the receptors. When this happens the generator electrode does not work as effectively and can contribute to low recovery on expected moisture levels.

What's the fix?

  1. Make sure to change the catholyte more often as required.
  2. Soak your generator electrode in methanol or even a light acid over night to clean out some of those salty deposits. That should help.

 

 

(Note: Coulomat AK anolyte and Coulomat CG-K catholyte are used in combination for samples with Keytones and have a 1 to 1 relationship and can measure 100,000 micrograms of water. Also, the popular Coulomat Oil anolyte has a smaller amount of moisture measuring capability as compared with the other mentioned anolytes above and has a capacity to measure 300,000 micrograms of moisture. eg. If your using Coulomat oil anolyte and Coulomat CG both have the capacity to measure 300,000 micro grams of water and have a 1 to 1 relationship.)

Hope this helps.

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