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.

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

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.

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.

ALSO READ OUR MOST RECENT UPDATES TO THIS BLOG POST : Salt related posts

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.

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.

In the video below we show the 600 series Karl Fischer Titrator.  Today we have additional models like the MKC-710 series that work with the ADP-611 solids evaporator.

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.

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

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.    Important note:1 ppm = 0.001 mg/g; 1 mg/g = 1000 ppm.

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 

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.

Simply put, drift is background moisture that the Karl Fisher titrator is detecting.  What is background moisture?  Well, it is moisture that the Karl Fisher titrator (specifically the detector electrode) is detecting inside the vessel -that’s not coming from your sample.  Drift or "background moisture" can be the result of having the titration vessel sitting idle for some time where moisture has slowly infiltrated and accumulated inside the vessel, or it may be the result of a leak that is allowing a small amount of moisture to enter the vessel continually.  Although we might like to think that the Karl Fisher titrator vessel is air-tight/moisture-tight, it is not.  Depending on how well the vessel is sealed there may be a little or there may be a lot of background moisture interference.  All Karl Fisher titrators deal with the drift issue.  Unfortunately drift cannot be completely eliminated but the good news is that it can be reduced, measured, isolated, and discarded from your test results.

Before a single test is run on a Karl Fisher titrator it must go into a “ready” mode.   But before the titrator can go into a “ready” mode it most likely will go through a “pre-titration” mode.  During the “pre-titration” mode excess drift (moisture) is detected and removed by the reagent inside the vessel.  A “ready” mode ideally will occur when the drift being measured is low and steady/stable – usually below .1 micro grams per second.  Once the drift becomes low and stable the Karl Fisher Titrator records the drift level and goes into a “ready” mode and will allow the operator to introduce a sample into the vessel.  Upon completion of the test the Karl Fisher titrator adds up all of the moisture detected over the duration of the test and subtracts out the known drift level that was also measured during the test.  This process of knowing what the drift was before the test allows the Karl Fisher Titrator to then determine and backout the drift -leaving only the moisture detected from the sample as your result.