Solving Titration's Difficult Problems
How labs can address solubility issues, when to use a fritless titration cell, and more
John MacFarlane, PhD, is the founder of JM Science, a scientific instrumentation provider specializing in titration and liquid chromatography equipment and accessories.
Q: Can you tell us more about your background and business journey?
A: I went into biology—I think I've been a biologist ever since I was a small boy. I did a postdoc in England on a NATO fellowship, was a research scientist for three years, and then had an opportunity to get into scientific instruments.
I was hired by a small company looking for an application scientist who knew a broad range of techniques. One thing led to another, and I decided to start my own scientific instrument company, JM Science, in 1989. We focused on liquid chromatography, but in 2004, Hitachi asked me to take on titrators. I wasn't intimately familiar with titrators, so I declined but eventually I realized the advantages of this wonderful product line. It was a great decision, and our primary focus has become titrators, applications, and liquid chromatography as a complement.
JM Science is a small company, so I look at the entire product envelope that involves all aspects of titration, for instance—installation, calibration, getting good results, maintenance, service, and technical support. We've always offered free technical support for the life of the instrument and remained very application focused.
Q: How can labs work around solubility issues or other difficult samples for Karl Fischer (KF) titrations?
A: Solubility is an important parameter that some customers forget about or overlook. Samples must be soluble in the KF reagent if they’re to be directly injected into the titration cell. Standard reagents are based on short chain alcohols like methanol and ethanol, so water insoluble samples need a special Karl Fischer (KF) reagent made for oils and organics. They usually have a little more chloroform or xylene to improve solubility.
If the sample isn’t completely soluble in the KF reagents, using an evaporator is the best option. There’s an evaporator for drying powders and an evaporator for oils that uses azeotropic distillation. Both use a source of dry air or nitrogen to carry evaporated moisture from the sample container into the titration cell, leaving everything else behind. They can be used with any manufacturer’s KF titrator.
Occasionally there are so many additives in a sample that the special Karl Fischer reagent for organics like aldehydes and ketones works just once. For example, automatic transmission fluid has scores of additives that would react to create false high results. In these cases, the oil evaporator is necessary. Other times, people choose to use the oil evaporator to keep the cell clean.
Q: What applications or industries benefit the most from these evaporators?
A: The oven attachment for powders is used a lot in the pharmaceutical industry. Manufacturers need to ensure that their powders—pharmaceutical agents in this case—are dry enough that they won’t grow things like bacteria and fungi.
The oil evaporator is necessary for difficult samples like all lubricants, oils, and grease, with heavy use in the petrochemical industry. It also should be used for samples that contain aldehydes, ketones, amines and other organics that interfere with the KF reaction.
We had a major food manufacturing and processing conglomerate come to us with a peanut butter problem. Peanut butter is one of those difficult samples that’s not very soluble in anything. They wanted to increase the moisture in their peanut butter by around 0.5 percent to save some money. Using an oil evaporator with our coulometric Karl Fischer titrator, they were able to increase the water content in the reformulated peanut butter to their satisfaction.
Q: What is a fritless titration cell, and when should people use it?
A: A fritless cell has an ion exchange membrane separating the analyte and catholytes, and people should use it if they're thinking about injecting an oil into a fritted cell. That oil sample can get into the frit and can be difficult to clean. So, customers like the fritless option because the membranes are easy to change and are very inexpensive. They solve the problem of plugged frits and are very rugged and reliable—you can handle them. Our default coulometric KF titrator comes with an ion exchange membrane.
Q: What should people consider for potentiometric titration applications?
A: Something to consider for potentiometric titrators would be the different electrodes required to do the analysis. Unlike with KF titration, which only uses a simple platinum electrode to measure moisture, there are different electrodes to go with different applications, for example, a silver electrode to measure chloride. Another application would be transmission lubrication people measuring the red color of the transmission fluid using a potentiometric titrator that has a photometric probe attached to the amplifier.
A typical application would be looking at organic acids in used motor oil using our standard pH and reference electrodes. Our lubricant customers will measure the concentration of organic acids in new and used motor oil, for example, to learn whether any of the additives made a difference in the amount of organic acids formed after, say 2,000 or 20,000 miles.
Q: Do you have more titration tips?
A: I tell people to think about additional sample vessels or even a sample changer. If you’re analyzing those difficult samples, say peanut butter, after measuring one sample you have a challenging cleanup. If you're running a few samples and have another clean vessel, you can analyze that sample with the azeotropic solvent. While that’s running, clean the glass sample vessel, dry it, re-grease it, and you are ready for the next sample.
The Hiranuma products come with a complete accessories kit, making the titrators turnkey. You get everything you need in your accessories kit and need to simply supply the sample and the reagent.
For the most part, you can use anybody's reagents. If you can save some money from a particular manufacturer, do that. Some places are experiencing supply issues. The reagent company we work with manufactures the reagents in Ohio, so they can ship quickly.
We recommend using fluorine grease on the ground glass surfaces because it doesn't harden over time like standard lab silicone grease. If the grease hardens around the ground glass joints, you cannot get the cell apart to clean it. They're handmade in Japan, calibrated, and very expensive to replace.
We also create real-time demonstration videos on how to assemble the cell, how to calibrate the unit, how to get good results, and how to maintain it, hosted on our web site. They’ve made a huge difference for customers and form a great training resource for lab managers or labs new to titration.
Q: Is there anything new and exciting on the horizon?
A: I just got back from Japan, talking to one of our manufacturers about some new instruments they developed that talk to one another. In the past, you would have to buy separate instruments for separate applications. You could have a potentiometric titrator for measuring acids in orange juice, for instance, and a KF titrator for measuring moisture in jet fuel. Now we can have a potentiometric titrator and a KF titrator networked together, and we can add auto-samplers, evaporators, and extra burettes. The whole picture becomes one massive set of instruments that all talk to one another. A customer can expand their lab, get into another application or a completely different technique, and add on to what they have rather than going to another manufacturer. I think that's very useful!
