This is a quick guide to getting started and running your first test.  We thought it would be helpful for those getting started and checking their first calibration before running tests with actual samples.  We will also continue to explore and share more information about calibration options, general maintenance, and data export methods using the DA-130N portable density meter in future posts.

First, lets review and identify the parts of the DA-130N Portable Density Meter:

 

 

 

O.K.  Now let's get started and install three 'AAA' batteries...

...And then attach the sampling nozzle.  

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A few words about precautions when taking test measurements.

When measuring a sample make sure to hold the instrument so that the sampling nozzle is vertical to the ground.  When laying down the instrument between or after measurements make sure to drain the remaining sample from the built-in syring (the built-in syringe is located inside the meter right above the sampling nozzle).

 

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Now let's run a preliminary test using water.  

1. Make sure the sample discharging lever is pushed down to the bottom.
2. If not, slowly push it down with your thumb.
3. Dip the sampling nozzle in the sample liquid.
4. Slowly pull the sampling lever with the forefinger. When the cell is filled with sample, release your finger.

Calibration of the measuring cell using pure water

Set calibration mode to OFF.  Press the [esc] key 2 times to return to the main menu.  Sample pure water making sure no air bubbles are visible.  The measuring cell with pure water can be calibrated automatically with the key entries as follows:  Press [cal.] key for more than 2 seconds to show CALIB(Water) (inversed colo on the display) showing calibration with pure water in progress.

After calibration is over the deviation from the theoretical value will be shown so that you can check if the calibration has been successfully completed.

Note: if after attempting re-calibration of the measuring cell and results are still not within specifications it is possible the measuring cell itself is contaminated.  In this case ensure to carefully clean the measuring cell and then re-calibrate again.

Note 1: You can also calibrate with a standard liquid that has a known density.  Sometimes calibrating with a liquid that has a similar density to your test samples will help improve precision.

Note 2: You can also calibrate with air.

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Some other useful things to know when working with different types of samples:

For more viscous samples over 2,000mPa.s it's a good idea to use the optional syringe adapter set. Almost any commerciall available syringe (plastic works great) will work.  You just need to order the female adapter to make it work (Adapter part number is 12-04428-02)

When working with samples under 2,000mPa.s of viscosity but where samples contain particles or grains that may crystallize when dry we suggest you use the supplied bellows pump (swap out the built-in syringe for this). 

 

We hope this information has been helpful!

Many of us have used the CSC Bostwick Consistometer and are familiar with it's operation.  Pressing down the gate and loading the trigger is step one.  Pouring in your sample and scraping off the top to a clean and even surface is important to getting repeatable results.  With a stopwatch in one hand, "popping" the trigger and letting the sample flow out and down the trough comes next.  Some tests are designed to see how far a sample will flow in say, 10 seconds.  Another testing approach might be to time the movement of the sample until it reaches a pre-determined point (bostwick).  If you have ever noticed in the bottom of the tray there are lines with numbers ranging from 0 to 24 (you really can't see a number 24 because the tray stops exactly at what would be 24).  Over the years these lines with numbers have affectionatly become to be known as "bostwicks". 

Most recently we have had requests to extend the length of the Bostwick Consistometer to accommodate samples that require more time and distance.  Not every sample flows the same way so this seemed like a good idea.  So to meet these needs we have now just started to offer a longer version of the Bostwick Consistometer!  Don't worry we still have the regular length Bostwick Consistometer available.

• The long version of the Bostwick Consistometer (part# 24925-000L) now extends from 0 to 32.  
• The regular length Bostwick Consistometer (part#  24925-000) has a range of 0 to 24.  

 

 

There is sometimes confusion about water activity and how it relates to water content.  Water content is how much.  Water activity (aw) tells us about the energy of the water.  Both are measurable.  

Water Content

We know a lot about water content and how to measure it using various popular methods including loss on drying, Karl Fischer titration, capacitance and more.  Water content is typically expressed in % or Parts Per Million (PPM).

Water Activity

Water Activity is the amount of unbound water in a sample.  Water that is not bound to the ingredients themselves can be used by unwanted microorganisms which could lead to one of the contributing factors for food spoilage.  Water activity is a thermodynamic measure of water expressed as the vapor pressure of water in a sample divided by vapor pressure of pure water at a given temperature.  

Water Activity is based on a scale from 0.0 to 1.0 

The more unbound water we have the more likelihood we have for microbial spoilage. Water Activity (aw) Meters measure the unbound water vapor pressures to determine microbial spoilage, chemical and physical stability. 

Well documented and scientifically established guidelines that are also supported by FDA regulations outline these thresholds of microbial limits using a water activity (aw) range or scale.  This water activity (aw) range provides the lowest rating for inhibition of microorganism and other degradative chemical and physical reactions that effect shelf life in foods (see chart below).  

                                     

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Water Activity & Growth of Microorganisms in Food

Range of aw	Microorganisms generally inhibited by lowest aw in the range	Foods generally with this range
1.00-0.95	Pseudomonas,Escherichia,Proteus,Shigella,Klebsiella,Bacillus,Clostridium perfringens, some yeasts	Highly perishable foods and canned fruits, vegetables, meat, fish, milk, and beverages
0.95-0.91	Salmonella, Salmonella, Vibrio parahaemolyticus, C. botulinum, Serratia, Lactobacillus, Pediococcus, some molds, yeasts (Rhodotorula, Pichia)	Some cheeses (Cheddar, Swiss,Muenster, Provolone), cured meat (ham), bread, tortillas
0.91-0.87	Many yeasts (Candida, Torulopsis, Hansenula), Micrococcus	Fermented sausage (salami), sponge cakes, dry cheeses, margarine
0.87-0.80	Most molds (mycotoxigenic penicillia), Staphyloccocus aureus, most Saccharomyces (bailii) spp., Debaryomyces	Most fruit juice concentrates, sweetened condensed milk, syrups, jams, jellies, soft pet food
0.80-0.75	Most halophilic bacteria, mycotoxigenic aspergilli	Marmalade, marzipan, glacé fruits, beef jerky
0.75-0.65	Xerophilic molds (Aspergillus chevalieri, A. candidus, Wallemia sebi), Saccharomyces bisporus	Molasses, raw cane sugar, some dried fruits, nuts, snack bars, snack cakes
0.65-0.60	Osmophilic yeasts (Saccharomyces rouxii), few molds (Aspergillus echinulatus, Monascus bisporus)	Dried fruits containing 15-20% moisture; some toffees and caramels; honey, candies
0.60-0.50	No microbial proliferation	Dry pasta, spices, rice, confections, wheat
0.50-0.40	No microbial proliferation	Whole egg powder, chewing gum, flour, dry beans
0.40-0.30	No microbial proliferation	Cookies, crackers, bread crusts, breakfast cereals, dry pet food, peanut butter
0.30-0.20	No microbial proliferation	Whole milk powder, dried vegetables, freeze dried corn

*Adapted from L.R. Beuchat, Cereal Foods World, 26:345 (1981) 

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Pure water that is unencumbered has more energy and therefore can be available and used to do bad things by microorganisms.  As water comes in contact with a material substance the water's energy and water activity (aw) decrease. Water reacts differently with different material substances and can have a higher or lower water activity rating* (aw).  A water activity (aw) number closer to the top of the chart closer to 1.00 has a higher water activity while those lower have less.

Understanding and documenting how water activity is effected by different material substances provides valuable information.   Using this information provides a way for us to take proactive measures to lower water activity as we seek to improve microbial, chemical and structure stability of foods, pharmaceuticals, and other materials. 

Packaging to improve shelf life

 

 

 

 

 

Equilibrium of ingredients to make foods last longer

Explore multi-ingredient products where water activity in each ingredient will seek to equilibrate and change the overall water activity (aw) result of the product.  This can trick people who only look at water content of each ingredient and or even the water activity individually.

      CONTACT US ABOUT------>    

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WHY DO WE CARE ABOUT BROMINE NUMBER AND BROMINE INDEX ANYWAY?

The degree of unsaturated hydrogen carbide (Hydrocarbon) in oil and petroleum products is indicated by Bromine number or index. Hydrocarbons containing between 6 and 10 carbon molecules are the primary components of most fuels where the process of burning them produces energy. Saturated hydrocarbons are defined by molecular structure and are defined as Alkanes.  Alkanes are the basis for petroleum fuels.  Unsaturated hydrocarbons are also defined by their molecular structure and produce less energy when burned than do saturated hydrocarbons.  Mathematically it therefore requires a greater quantity of unsaturated hydrocarbons to be burned to equal the same amount of energy produced by burning the same amount of saturated hydrocarbons.  An un-friendly environmental side effect of burning hydrocarbons is the creation of carbon dioxide.  So from an environmental standpoint you could say we prefer the lesser of two evils and prefer to burn saturated hydrocarbons vs. unsaturated hydrocarbons. For these reasons alone it would make sense that we would want to measure and quantify these hydrocarbons. 

 

HYDROCARBONS AND SOME OF THEIR USES

NAME	USES
Methane	Fuel in electrical generation
Ethane	Chemical applications
Propane	Heating and cooking
Butane	lighters and aerosol
Pentane	Lab & production of polystyrene
Hexane	Glue
Heptane & Octane	Major contributor to gasoline
Nonane	Diesel fuel
Decane	Jet fuel, gasoline and diesel

 

Although the test method ASTM2710 describes the use of an automatic potentiometric titrator the coulometric Karl Fischer method is easier to perform (see ASTMD1492-08e1).  

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<BROMINE NUMBER AND INDEX BY COULOMETRIC KARL FISCHER TITRATION>

 

<PRINCIPAL OF MEASUREMENT>

Special notes to obtain correct measurement results:

1. Replace anolyte and catholyte reagent often (daily).
2. When anolyte turns to white color replace it with new anolyte.
3. Over use of anolyte and catholyte and not replacing it can cause results to be higher than expected.
4. Do not share Bromine titration cell with a moisture titration cell

 

Step 1: Preparation of Reagents

 

Step 2: Prepare Reagent for testing

Step 3: Measurement Procedure

Measure Bromine Number and Bromine Index

*Note that different Karl Fischer Titrator Models will have different button commands.  The MKC-710 series coulometric Karl Fischer titrators come standard with pre-programmed setup for running Bromine and follow the above button commands.

We hope this information helps you get started.  If you have any questions or would like some help please contact us by clicking on the button below.

 

 

 

How to Clean Karl Fischer Electrodes:

A Karl Fischer Titrator uses two electrodes.  The Inner burette (aka Generator Electrode) and the Detector Electrode.  We hope this information is helpful in giving some guidance on cleaing and caring for these Karl Fischer Titrator electrodes.

 

 

Cleaning with alcohol: general method

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ELECTRODE RINSE WITH SHOWER ACCESSORY:

Sample changers that are connected with automatic titrators generally are there for a reason.  Efficiency. From an operators point of view getting multiple tests done quickly while being able to take on other tasks in the lab is a key productivity booster.  Sample changers offer various sizes ranging from as few as 6 positions for samples up to some of the largest exceeding 50 sample positions.  Sample changers either have rotating carousels or an arm that moves electrodes and nozzles from sample to sample.  Each time a sample test is completed the electrode must be cleaned before moving on to the next test.  Many sample changers offer as standard a dip rinse between sample testing and as the name suggests it's really nothing more then dipping the electrode in clean water or solution.  For some samples this process is sufficent but for others it is not enough to effectively clean the electrode before the next test.  Luckily most manufacturers of sample changers offer additional cleaning power with the use of a shower rinse system.   Below is a video showing how a shower rinse process works.   Water is stored in a container and then is flushd and rinsed in one of the sample positions designated as the cleaning station.  Water is evacuated via tubes to a drain or sink.  

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There are MANUAL TENSIOMETERS that look like this:

PROS:

• >Great for hands-on learning
• >Can use virtually anywhere (does not require electricity)
• >Easy to learn how to use
• >Less expensive

CONS:

• >It's manual.  You have to twist the dials by hand
• >There is a technique to getting repeatable results
• >Human error potential is higher
• >Need to record results by hand

 

VIDEO DEMONSTRATION FOR MANUAL TENSIOMETER

There are AUTOMATIC TENSIOMETERS that look like this.

PROS:

• >Easy to operate.  Press a button and walk away
• >Run more tests quickly with high repeatability
• >Ability to record and report data results (store historical data too)
• >Dynamic testing features including time tests and Lamella length and more
• >Most handle both DuNouy Ring and Wilhelmy Plate

CONS:

• >More Expensive
• >Some models require a computer (some don't)

VIDEO DEMONSTRATION FOR AUTOMATIC TENSIOMETER

 

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.

 

                        

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From start to finish watch this short video to see how a sample of Jet Fuel Oil is tested for water content using a karl Fischer Titrator. For this training video we use:

1. The Aquapal III coulometric Karl Fischer Titrator (setup as a dual reagent configuration)
2. Reagents; Anolyte is coulomat AG and the catholyte is coulomat CG
3. A 4-place analytical balance SA-210
4. And a disposable syringe and disposable needle

In this video you will see the steps for running a test successfully including how to:

1. Extract your sample into the syringe
2. How to weigh your sample and tare the balance
3. How to inject a sample properly
4. How to input the sample weight and obtain a final result

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We hope you found the video helpful and informative!  If you think a colleague could benefit from this please share it with them!  Click on the twitter button to automatically share this video!

"How to test for moisture in Jet Fuel Oil using a Karl Fischer titrator"

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Thanks for Watching!

Many people use coulometric Karl Fischer Titrators to measure low level moisture at the part per million (PPM) level.  When it's time to start testing it's critical to have an understanding of how to:

1. Properly identify the glassware components
2. Assemble the glassware
3. Identify the reagents  (anolytes and catholytes)
4. Introduce the reagents required by the instrument and the sample being tested 

Once you have these concepts down you will have a strong working knowledge of how a Karl Fischer Titrator works and how to trouble shoot future problems.  Watch this short training video to learn more.

If you found this information helpful please share this with your colleagues!  Just click on the tweet this button.

  "Karl Fischer Glassware and reagents 101: Properly identify the glassware components, Assemble the glassware and Identify the reagents"

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We hope you find the training video helpful!
Thanks for Watching!

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Karl Fischer Glassware and Reagents 101:  How to setup.

 

It seems sometimes we overlook the obvious and forget to explain some of the most basic concepts.  Sorry about that.  So we thought it might be a good idea to show how Karl Fischer Glassware is setup and how we introduce or "charge" the vessel with reagents.  We hope you enjoy this short video tutorial!