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

If 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.

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 cathoyte 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.

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.

In these last two pictures we show a Karl Fischer Vessel with a Single-Reagent Generator Electrode inside. Notice how there in no frit at the bottom? -All you see is the platinum screen. In the other picture you can see the bottom of a Dual-Reagent Generator Electrode.  See the white wafer?  This is where the deposit build-up occurs.  Just thought it would be helpful to show both and the differences.

(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.

How to use a titrator to measure % sodium chloride in food products

Titration

So you need to measure the amount of sodium chloride in your food products. While we have written about this topic previously in other posts and addressed some of the approaches used to test for % sodium chloride (including the use of hand-held salt meters) we have found that it is a more common practice to use an automatic titrator to accomplish this task.  In fact we think it is the preferred instrument and method of choice.  To be sure there are pros and cons to using different methods but we still find that titration is accepted as the primary method for getting the most accurate results.

 

How it's used

Although salt meters using the conductive method are faster (3 seconds vs. 2 to 3 mintues) and can be employed quickly in a production line process, titrators can also be implemented in the same testing environment with modest effort.  Additionally and regardless of how the tests were performed on the production line, titrators are generally put to work in the Quality Control/Quality Assurance Lab as a final check against periodic production line testing.

Supporting the use of titration as an accepted method includes some well known documented techniques including Mohr's and Volhard's methods making titration a recognized and trusted approach.

 

What's next...

Once you have made the decsion to use titration as the testing method it's just a matter of knowing:

• What items you need

• How to prep your sample

• How to setup the titrator

Luckily we have already thought about this and put together a list of 8 items your going to need.  We also created an application-note providing step-by-step instructions for you to follow to conduct a titration.

                                 

                                          

 

                                          

How to test for Salt during food production

Many companies produce the foods we eat.  Do you ever wonder why or how they test for salt during the production process?

Examples by Manufacturing Type

Frozen Vegetable Processor	The salt content of the blanching water is important for maintaining the bright colors of vegetables
A Condiment Manufacturer	Testing Sauces and dressings
A Cheese Maker	Measure the salinity of saltwater that the cheese is soaked in
A Potato Chips Manufacturer	Checking for salt sprinkled on fried potato slices
A fresh Cut Fruit Processor	Use a 2% saline solution with a small amount of ascorbic acid to prevent discoloration of fruits
A Deli Food Supplier	Measure foods with a salt meter vs. by taste
A Canned Food Manufacturing Plant	Measure the brine for canned tuna
A Pickles Manufacturer	Measure the salinity of the brine for salt-packed products
A Cold Cut Meat Manufacturer	Measure salt concentration of ham and deli slices
A Baker	Measure and monitor the salinity of bread dough to around 1%-2%

 

 

 

Salt which is made up of 40% sodium and 60% Chloride is an important ingredient found in food.  While salt can make food taste better, control color, and maintain food texture, it is also considered a health-risk factor (mostly due to the sodium).  Measuring and controlling the levels of salt between the extremes is a constant battle.  Producers of processed foods generally have the biggest need for identifying and controlling salt levels to address not only the taste, color, and texture of foods but also to address some of the healthier eating lifestyles more and more consumers are demanding.

For these reasons it is paramount that salt is measured accurately.  So how do we do that?

Food comes in a variety of forms.  Solid, Liquids, pastes, creams, pieces, chunks, wafers, crackers, gooey, sauces, liquids with chunks in them...let's see what else..Anyway, you get the idea.  There are a lot of ways food can be produced and consumed!

So what device or devices can we use to measure the salt found in these numerous forms of processed foods?

Well, there are a number of "salt meters" out there that can measure salt.  However, not all salt meters can measure the particular salt you are looking for in the same way.  In fact some "salt meters" can only measure salt under certain conditions and or in certain substances like water or sea water.  For this reason it is important to first consider what your going to be testing.  For example, If your food sample includes "food stuff particles" that you can grind into a paste form, then you can probably use a salt meter that utilizes the conductivity method.  On the other hand if you have a brine that you immerse food into and your only concerned with the liquid then perhaps a different salt meter will work.  

The point is this.  The form of the food at the instant you are going to perform the test is key.  Many types of foods can be formed into pastes and diluted with water.  If the food you need to test is like this then a simple salt meter utilizing the conductivity method may be able to perform the test to your satisfaction.  I say may because % salt levels and other accuracy factors may require that you use an entirely different method of titration known as silver nitrate titration instead.

Salt Meter vs. Titration?

              

A brief explanation and description of the two measurement approaches:

The Mohr method, also known as a silver nitrate titration method, utilizes the characteristics of silver nitrate that reacts with chloride ions to measure the salinity %. 

Conversley, some of the more popular salt meters emloy the electric conductivity method.  Both methods measure the salinity but operate on different measurement principles.  However, by creating a conversion table between the two testing methods, correlation between the set of results can be seen.

 

Aside from the measurement capabilities of each approach there are pros and cons to each.

 

 Pro's and Con's

	Salt Meter	Titration
Measurement Range	Less..maybe	More
Accuracy	Less	More
Ease of Use	More	Less
Time to test	Less	More
Cost	Less	More

 

 

 

 

 

 

 

 

 

 

 

 

 

While each method has benefits we have recently found through some informal surveying that some food processors are choosing to use both methods.  These companies are finding that it is easier to use the hand held devices and perform quick spot checks on the production line.  If any problems are identified on the production line then further verification and testing can be performed using the titration approach.  Some think using this collaborative approach is ideal.

 

 

How Much Does a Tensiometer Cost?

 

Tensiometers are instruments used for conducting surface analysis on liquid substances.  Typical applications Tensiometers perform include measuring surface tension, interfacial tension as well as liquid density and Lamella Length on some Tensiometer models.  Some models can also perform other tasks including powder wettability and dynamic contact angle of a solid substrate.  Depending on the types of information the operator is seeking to find one model may be more appropriate than the other.

 

To help prospective users evaluate and compare the different types of models available in the market we have prepared a reference document we call the:

 

"Tensiometer Selection Matrix"

 

This matrix is not necessarily brand specific as it was designed to help those seeking to compare capabilities and prices among popular manual Tensiometer models vs. popular Automatic or "digital" Tensiometer models.

 

We hope you find the Tensiometer Selection Matrix helpful in your search and evaluation of Tensiometers.

 

Can a Karl Fischer Titrator measure moisture in a solid sample?

YES IT CAN!

You can measure moisture in solid samples including plastics, powders, ores, gooey substances that are thick and viscous, greases, and many more.  The key is sample preparation to ensure that a uniform material will be tested.  Once those details are worked out the pattern for testing is the same every time. 

You hear a lot about people running traditional Karl Fischer titration using direct injection with a syringe and needle. That’s pretty easy. 

 

So how do you test for moisture in solids?

For more awkward samples like a solid or solid-like substance we can evaluate the moisture using a Karl Fischer Titrator with an Evaporator Oven.

Believe it or not that’s pretty easy too. I guess that’s why we wrote this post. We wanted to let readers know that the process for running a Karl Fischer moisture test using an evaporator oven is not that difficult.  As mentioned already the most difficult part is probably working with your sample. To help show how the process works we created this short 7 minute video detailing the steps along the way. Please make note that the instruments used for this demonstration are the Karl Fischer Titrator (MKC-610DT) and the Evaporator Oven (ADP-611).

Hope you enjoy.

Where can I get an electrode repaired? - Karl Fischer

We work with numerous titrator models and encounter many of the day-to-day problems associated with broken electrodes.  In many instances some of the electrodes are destroyed beyond repair but in other circumstances we find that some are in fact capable of being repaired. 

Most of our success with repairing or refurbishing electrodes is with Karl Fischer Generator Electrodes (also known as Inner Burettes). 

However, we do try to evaluate and determine whether other types of electrodes can be repaired also.  Generally we will ask for a photo or other description of the damaged electrode to determine if a repair is possible.  An example of how we examine a typical Karl Fischer Generator Electrode can be viewed in the following short video.  Take a look and let us know if we can help you.

WBGT and Washington State Safety

On July 5th, 2008, a workplace rule designed to protect workers from outdoor heat exposure took effect in Washington State. This rule was passed on June 4 after six public hearings were conducted on heat stress and its causes. The hearings confirmed what officials already knew: working outside in hot weather is a health hazard.  The three requirements for employers with employees who work outside are to:

·  Train employees and supervisors to recognize heat-related illness and what to do if someone has symptoms.

·  On days when temperatures require preventive measures, increase the volume of water available to employees.

·  Have the ability to appropriately respond to any employee with symptoms of illness.

 

It's now 3 years later...would a handheld WBGT Meter be a helpful tool?...

 

The Wet Bulb Globe Temperature (WBGT Handheld meter) is a tool perfectly suited to helping Washington State employers comply with this new law. This hand-held tool is used to estimate the effect of temperature, humidity, and solar radiation on humans and determine appropriate exposure levels to high temperatures. A WBGT index is commonly used as a guide for environmental heat stress to prevent heat stroke during physical exercise or while at work. Based on the index shown, employers can estimate the probability that a heat-related illness with occur and provide the appropriate amount of water available for the current weather conditions. See a video demonstrating the use of the WBGT103 below.

 

For more information on the new Washington State law, go to: http://www.lni.wa.gov/safety/topics/atoz/heatstress/default.asp

I'm Having Problems with my Volumetric Karl Fischer Titrator

Most operators who measure moisture using a Volumetric Karl Fischer Titrator tend to have difficulty in 3 areas.   Unlike Coulometric Karl Fischer Titrators where the equipment setup and reagents are fairly straight forward, Volumetric Karl Fischer Titrators differ greatly.  Understanding how a Volumetric Karl Fischer Titrator differs and how the equipment functions is not only paramount in terms of knowing how to operate the instrument it is critical if you want to obtain accurate and repeatable results.

8 out of 10 questions we receive usually fall into one of these 3 problem areas:

 

1. What REAGENTS should I use for testing my samples?  Titrants, Composites, Solvents?

2. "TITER VALUE" ..Who, What, Where, Why and How?

3. "SAMPLE SIZE" ..How much do I need or should I use? 

Although these 3 areas at first may seem problematic and unrelated they are not.  In this 9-minute presentation we will explain why the burette size matters, how to calculate a correct sample size and explain how the volumetric titrator reagent strengths work.  Tying all three areas together will hopefully not only clear up some of the mysteries surrounding Volumetric Karl Fischer Titration but also empower operators with choices for conducting tests under varied conditions.  And, oh yes, obtain accurate and repeatable results every time. 

Karl Fischer Titration and Water Standard Presentation

In this presentation we discuss the basic Karl Fischer Water Standards and talk about some of their uses for both Coulometric and Volumetric Karl Fischer Titration.  We also describe some of the related problems that can be identified and overcome by using Karl Fischer Water Standards.

• Karl Fischer Water Standards
• Why we use them
• Coulometric Karl Fischer
• Volumetric Karl Fischer

 

Karl Fisher Titration and the 20 Most Critical Questions

As a service provider of Karl Fisher testing apparatus, we see different moisture testing issues that many operators, managers, and even companies face. We have come to realize that helping operators become more knowledgeable about "the little things" can help boost confidence, improve performance and efficiency, and ensure accurate testing. 

Are you new to Karl Fisher Titration and just beginning to learn about moisture testing or has it just been a while since you had to pull the Karl Fisher Titrator out to run some tests?  Regardless of your reason we know how important it is to get up to speed quickly so you can be running tests and providing moisture test results to those who need them.

To help with this we have compiled a list of the 20 most critical questions to help operators navigate through the learning curve and gain a better understanding of Karl Fisher Titration.

Some examples of issues you will discover include:

1.  "Our Karl Fisher says 'OVER TITRATION' and the reagent is turning really dark. Why?”

2.  “Why won’t the instrument go into “Ready mode”?”

3.  “Results seem "all over the place", what should I do?”

4.  "We use a solids evaporator and we are getting ZERO moisture results. Why?"

5.  "How many tests can I run and when should I change out my reagents?"

 

Avoid unnecessary surprises by getting a copy of the complete list of questions and learn what the issues are and why they are important.