Mettler-Toledo International Inc. (MTD) Earnings Call Transcript & Summary

Welcome, everyone. We'll get started here in a few minutes. Feel free to put your questions in the chat throughout the webinar, we can address them at the end. We will also have a live demonstration of our SevenDirect meter at the end as well, and it also includes a poll question. Thank you.

Hello, and welcome to Mettler-Toledo's lab webinar. My name is Renee Doran, and I'm a lab market specialist here at Mettler-Toledo. Get the most out of today's webinar. Don't worry if you miss anything, we will have it on demand on our website shortly after this live session. Participate in polls. We would love to hear your perspective and also there will be a survey at the end of the webinar. [Operator Instructions] We offer a broad range of solutions across our customers' value chain. This will help you to streamline your processes, enhance productivity, reach compliance with regulatory requirements, and optimize cost and reduce waste. And now on to the Webinar.

Welcome to our Mettler-Toledo webinar about errors and PH measurement. My name is Taylor Vennemeyer and I am the U.S. Market Manager for our pH solutions. In this session, we will investigate the different errors that can occur and provide some best practices to reduce these errors in your daily pH measurements. The agenda for today is simple. First, let's go over the source of pH measurement errors followed by a short best practice review and demonstration. In this first chapter, you will learn that several challenges can create errors in your daily measurement. Therefore, we will go through a short overview, followed by the liquid potential, alkaline and acidic errors, temperature, membrane and last but not least, the meters themselves. Okay. Let's dive in. Many pH measurement errors influence the accuracy of your results with several of these listed here. These errors can easily be minimized and an accuracy of plus or minus 0.02 to plus or minus 0.05 pH can be achieved when following the best practices that discussed today. This will deliver a deeper understanding of the possible errors you may face in your daily routine. This fishbone diagram for PH measurement, we can see various uncertainties, which lead to an overall error in pH measurement. The green highlighted section reflects the uncertainties related to the calibration, mainly from buffers. Depending on the production, quality, storage and age, buffers can tremendously impact a proper and accurate calibration. The errors that can happen during measurement, however, are listed in the orange highlighted area. The essential key message is that the measurement errors are not only introduced during the measurement, but also during calibration when the buffers are being used. All 3 of these components add up to the overall error. This is especially important for those who'd like to calculate uncertainty. However, this presentation will not discuss how to build out a quantitative model for uncertainty calibration. More important is to see that the pH calibration and measurement are affected by specific errors, which will accumulate to the overall measurement error. On the previous slide, we saw a more theoretical model of the sources of overall error. Here, we will look at more practical sources to allocate our actions to improve the pH measurement. One important error in pH measurement is visible here in the purple area. Often, users forget about the liquid junction of potential error despite its possible significance. In the dark blue area, we can see the other quantifiable errors. First, to the left in the blue area, we have the conditional alkaline or acidic error. These errors appear in the relatively alkaline or acidic range of the pH scale. The acidic error is usually less crucial than the alkaline error. We will talk later about the reason for this. The temperature has various effects on pH measurements. And for more in-depth information, please check out our on-demand webinar about temperature effects on pH measurement. The error introduced by the temperature measurement is up to 0.3 pH units, while the compensation is up to 0.1, without temperature compensation, the error would be a multiple of the respected error. Finally, the quantifiable error is the so-called linearity error. The 08:26 Nernst equation indicates a linear pH behavior. However, this is only the case for an ideal measurement system. In a real system, even if accounted for acidity and alkaline error, there is no perfect linear slope. This error happens mainly of the calibration has been performed as a 1 point or 2-point calibration. And especially this occurs if the pH is not within the range of these calibration points. In the light blue area, we see the nonquantifiable errors. The contamination error and the asymmetric cell error on the left side do not directly introduce error in the pH measurement, but influence the stabilization time required for an accurate reading. Thus, an error is usually introduced while the measurement has not yet stabilized and it is difficult to see when the measurement has stabilized even in a sufficient algorithm being used. The membrane resistance in meter errors are quantifiable for certain types of equipment used but are largely dependent on this equipments. If we sum up the errors, as the errors behave additive, the maximum error introduced in your measurement could be up to 1.6 pH units deviation. However, this maximum deviation from the actual value can typically only be observed in extreme pH scale ranges. Therefore, a realistic error according to good electrochemistry practices is normally below 0.05 pH units. Let's have a closer look at some of these described errors. The liquid junction potential occurs, the 2 electrolyte solutions of different concentrations are in contact. Looking more closely at the sensor tip we can see the junction as the white spot in the red highlighted square right above the sensor membrane. In this example, we have a diaphragm style junction. Mettler-Toledo offers different junction types depending on the application and sample material. For example, the Inlab expert Pro family contains 2 open junctions for samples that contain materials that often block the ceramic junction. Either way, the junction is where the liquid junction potential is built up and as we know now, may lead to significant errors. The outflow is given by the physical parameters of the diaphragm and the level of the electrolyte in the electrode, often KCL solution within the reference system. The ion Exchange depends on the difference in ion concentration and the type of ions passing through the diaphragm or junction. If we look at the above graphic we can see that the mobility of the chloride ion is much higher than that of sodium. Thus, a charge separated layer can build up where an additional potential between the layers is measured. The graph shown on this slide displays different ions and their mobility. Clearly visible is that the hydroxide ions and hydrogen ions have the highest mobility among all other ions listed. We can also see that potassium chloride is a better combination than sodium chloride. Not only could the alkaline effect be avoided with this combination there is also a benefit due to the similar ion mobility, meaning potassium ions are almost as fast as chloride ions. Thus, the charge separated layer for this salt is less pronounced than using a sodium chloride salt. The liquid Junction potential error is especially large at the ranges outside pH3 and 11. As the ion mobility of hydrogen and hydroxide is very high at these ranges the concentrate and gets higher and they can influence themselves. The general ion mobility is influenced by the concentration difference between the 2 solutions. As we explained in the initial theoretical model, not only are the errors in the measurement important, but also the calibration process itself. With the liquid junction potential in the calibration solutions is similar to the one in the sample measurement, there will be less of an error than if they significantly differ. Ideally, the sample and the buffer would have the same ion types in the same concentration present to avoid an error. However, this is not feasible without significant effort and the error introduced from the different ion shrinks is under normal condition is negligible. Still, the user has the option to reduce the overall junction potential error by stirring. By doing so, the solution gets homogenized, which means the concentration is similar everywhere in the solution. Additionally, the charge separated layer built up at the junction gets destroyed or reduced with stirring. This happens as the amount of solution is large enough to take up the ions from the reference system without changing the ion concentration. Without stirring, the concentration could change locally. Stirring during measurement reduces the liquid junction potential effects to a minimum. Nevertheless, remember not to stir too vigorously as this would introduce other errors, such as air bubbles in the measurement. Now let's discuss the alkaline error. The theoretical slope of a pH meter is linear in the full range. This is given by the Nernst equation. However, the behavior is not entirely linear when measuring with an actual electrode. In the graphic, we see around pH 14, the actual behavior differs from the linear behavior. In this range, we talk about the alkaline error. The sensors membrane is the most important place for pH measurements. This is where the hydrogen ions are sensed and create a potential dependent on the concentration of hydrogen ions. Unfortunately, the membrane glass is sensitive to the concentration of hydrogen ions and to a smaller extent, sodium ions. As we can see in the graph, the higher the sodium concentration is the bigger deviation from the actual value. At concentrations above 1 molar sodium chloride, the deviation is larger than 0.2 pH units. This sensitivity not only appears in the higher pH range and worsened as the pH increases at a constant concentration of sodium chloride. This graph concludes that the impact can be as high as 0.5 pH units deviation at concentrations above 1 molar sodium chloride and pH14. The measured values are too low compared to the actual real pH. Non visible in this graph is the effect is pronounced at a higher temperature. When measuring in a high pH range at high temperature and high sodium concentration, it can be that only the sodium concentration and the solution is measured. With the meter then displays is the negative logarithm of the sodium concentration. This alkaline effects start around pH9 and worsens with increasing pH. One note to mention, the membrane is not only cross sensitive to sodium, but also lithium. However, lithium ions are seldom observed in everyday chemistry. An influencing factor we did not discuss on the previous slide is the effect of the membrane glass. As we can see on the graph if we keep the sodium ion concentration content at 2 molar and increase the pH value of the solution, we can observe a different behavior for different membrane glasses. The alkaline error highly affects the LOT membrane glass and the deviation from the actual value could be as high as 1.6 pH units. This glass is designed for low temperature and low ionic strength measurements and is thus unsuitable for high ionic strength measurements. Other membrane glass types at Mettler-Toledo are designed for high alkaline or high-temperature environments that are far less affected by the alkaline error. Also visible on this graph is that among the tested glasses and concentrations, the effect is not present below pH9 as stated on the previous slide. The user can reduce the alkaline error to a minimum by using the right electrode, either HA glass or A41 glass. If avoidable do not measure at high temperature as the effect worsens with increasing temperature. If we go back to the whole range and the behavior of the pH electrode, we see that not only in the alkaline range thus the actual behavior deviate from the theoretical, but also in the acidic range marked in the red square. A common explanation for this error is that the hydrogen ion activity is reduced due to various effects. To review from pH theory, the pH measurement sensor does not measure the ion concentration of hydrogen, but rather its activity. How the activity is finally reduced around the membrane or within the solution is not yet fully understood. The impact of this effect is that the artificially high pH values are measured. This means that while the [ real ] solution has a pH of 1 the measurement displays 1.2 pH. The acidic error is less disturbing to most measurements as it only appears at very low pH values around 1 pH. A possible countermeasure, if one needs to measure at such low pH values is to measure connectivity instead. If the pH value is that low, the ion concentration from the acid is very high at around 1 Molar. If no other salts are present in high concentrations, the connectivity measurement is more accurate than a pH measurement. With the exceptions mentioned before, the behavior of a pH measurement chain is linear. This is explained by the Nernst equation. In this equation, we can see that the temperature has a linear effect on the slope. Together with the offset, the slope translates the millable reading of the potentiometer, to a pH value. At 20 degrees Celsius, the slope is negative 58.16 millivolts per pH. If the temperature increased to 25 degrees Celsius the slope changes to negative 59.16 millivolts per pH for an ideal sensor. From this change in slope, we can see that if the temperature reading is not compensated, the resulting error would be significant. Important to keep in mind is that the meter compensates for the temperature effect from the calibration onto the measurement chain automatically, not the temperature effect on the sample itself. In fact, temperature changes ion activity in solutions and thus changes the pH, and this effect cannot be compensated automatically as it is unique for every sample type. Besides the error from the time needed to adapt to the temperature, there is another error that can occur while measuring pH. Independent of whether you measure the temperature with a temperature probe integrated into the sensor or with a separate one, the measurement of temperature has an error too. It depends on the elements used and, to a lesser degree, on the electronics to convert the signal. As we can see on the graph, the error introduced depends on which pH we measure temperature. The error is largest when measuring at pH 0 and get smaller when measuring closer to the isothermal point, which is slightly above 7. A second error is introduced through the temperature compensation. As we heard before, an even larger error would be introduced when not compensating for the temperature. When calculating the ideal slope the meter assumes the isothermal point is at pH 7 and 0 millivolts. However, in an actual sensor, the isothermal point is slightly above 7. This error is smaller than 0.1 pH units. Countermeasures are difficult and have little significance, so there's no high priority to reduce this specific error. Now let's look at membrane contamination. There are 2 places where contamination can affect measurements aside from carryover effects. The first is at the diaphragm marked in the red square. Various chemicals, proteins, fats or reactions can clog at the diaphragm. A clogged diagram as visible in the photo leads to reduced electrolyte outflow and thus to unstable measurement for a longer time needed to reach a stable value. A clogged diaphragm can be clean, though, Different cleaning agents are recommended depending on the type of contamination. The second possibility where contamination can occur is the membrane itself. Some chemicals such as fluorides and carbonates, are strong enough to react with the glass membrane. However, this is not the same when using a regeneration solution and conditioning afterward. In addition, sticky oils and fats can cover parts of the membrane. Both contaminations lead to a reduced active surface area and thus, to a sluggish or slow response. Different approaches can be chosen to counter the contaminated membrane depending on the type of contamination. For example, hot water could be used if sticky fats or oils could not be washed away with water. If it is still not working, organic solvents can be used for a short time. And afterwards, the membrane must be regenerated in 3 Molar KCL. Also on the meter side, we find other sources of error. The meter has a defined sensor input accuracy, but the input can be contaminated or rested. This would significantly increase the risk of a measurement error. Also, internal contamination or operating at the limits for operating conditions introduces significant error in the measurement. For example, the resistor used for measuring is affected by temperature, the higher the temperature the lower the resistance. To counter those errors, it is advised to use good quality meter to operate within the specified limits and to clean the inputs from time to time, especially when placed in a harsh wet or corroding environment. In our last chapter, we will talk about recommended best practices. The right selection and handling of the buffer enables reliable results for pH measurements. In order to do so, the buffer selection for the calibration should always cover the complete pH sample of measurement range. If you measure your samples in a wide pH range, then the difference between 2 consecutive calibration points must not be further apart in 3 pH units. Ensure that you have chosen the dedicated buffer group for the meter. It is highly recommended to use the predefined buffer groups in Mettler-Toledo meters to reduce possible mistakes. Never use solutions that are expired or reuse buffers as this adds to additional errors. If you stir your sample, then you must also stir the calibration solutions in order to ensure accurate results. The other important component of pH best practices is sensor handling and maintenance. Let's talk about the 5 most common problems you may have faced with sensors during your measurement. One, if the membrane is dehydrated or the junction is blocked, conditioning for 12 hours with a 0.1 molar HCL solution may resolve the problem. Two, if you have proteins in your sample that can block a junction, you will need to place the centers for at least 4 hours in a pepsin HCL solution. Number three, it might happen that you have air bubbles behind the junction, which will block measurement results. In that case, carefully shaking the sensor or placing the sensor in a warm water bath will quickly remove the air bubbles. Number four, another problem that can be easily solved is the electrolyte level and the electrolyte condition. The electrolyte level must always be higher than the sample level to ensure a proper flow out of electrolyte solution into the sample. And number five, finally, the sensor is worn out. In that case, you can only resolve this problem by replacing the sensor with a new one. I would like to review common problems in practical solutions during this section. If you calibrate your electrode and the slope is below 95%, you should perform a conditioning step overnight in 0.1 molar HCL. If the slope is below 90% the electrodes worn out and should be replaced. Looking at offsets. When the offset exceeds 20-millivolt the electrode to be conditioned in 0.1 Molar HCL. If the electrode reaches 30 millivolts and more the sensor must be replaced. If you see crystals in the electrolyte chamber, remove the electrolyte by rinsing the inner chamber with de-ionized water several times. In the case of very persistent crystals, the de-ionized water can be warmed up. After rinsing, fill the inter chamber with fresh electrolyte. If you notice a long response time that reaches several minutes in new unexpired buffers replace the sensor. Now that we have learned about the possible measurement errors that can influence pH measurement and introduce countermeasures, let's review the key messages from this course. To improve the accuracy or reliability of your measurements, work on the most influencing factors first. For example, do not focus on tiny errors introduced such as the error that happens when assuming that the isothermal point is at pH 7. Next, select the suitable sensor for your application. Most of the errors are center-dependent, such as the alkaline error when using the wrong membrane glass. The membrane resistance error with having the high resistant glass for low temperature measurements or the measurement contamination error when using a diagram-based sensor when measuring in fats. Stirring the solution at low speed improves the measurement considerably. As we have learned, the junction potential error could be reduced vastly by just stirring the solution, not to mention that the solution is more homogenous when stirring. Performing a measurement and calibration at similar temperatures and avoid big jumps in temperature when measuring. One way to achieve this is to store the buffer, the sample and the sensor at the same temperature. Select a good quality meter from a trustworthy supplier, remember that details matter, such as the quality of the components used, the manufacturing process and so on. Finally, calibrate your sensor regularly with fresh, high-quality buffers to ensure correct slope and offset. With the summary of recommendations, we'd like to end the presentation, and thank you for your attention.

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Hello, and good afternoon. My name is Matthew Stinson. I'm a laboratory solutions rep here at Mettler-Toledo. And today, I want to show you 2 of our top -- bench top pH meters. We'll start with the one of the far side, which is our SevenExcellence instrumentation. That is a potential triple channel instrument where you can do pH, conductivity, dissolved oxygen. It's a modular system, you could swap out the modules on the back. You could have 3 pH electrodes connected at one time, pre-conductivity even dissolved oxygen, however you want to measure whatever the best need is for your solution and for your sample types. That system is also capable of connecting to our LabX software which if you're on a pharmacopia environment or a highly regulated customer or if you need to connect to a multi samples when you talk about maybe 25 or more samples, we can also connect that instrument to a [ Carousel ] and automate your process and you're measuring needs. If you're also want to lock down situation, you want to do a highly strong administrative controls, you can do that with the SevenExcellence instrument as well. But today, we're going to mainly focus on the SevenDirect, as mentioned into the webinar. The SevenDirect is very, very useful, is highly accurate for pH, ion and conductivity measurements. The instrument is very robust as IP54 dust and water-proof rating. The instrument will ship with a, let's call it, end-use cover for protection of spills, anything like that to protect the touch screen. This is a 7-inch touchscreen. The screen, if you swipe here on the screen. You can get to all the menu settings on the instrument there. You can scroll through. User management controls are located here as well. You can either tap or swipe back, if you scroll down, this is where all your methods are stored. If you go through this instrument, you can label all your methods 1, 2, 3 unique names, things of that nature. If you scroll back up and once you've taken all of your measurements, you scroll from the opposite side, there shows all of your results. Your results will be listed and you can scroll through. There'll be time stamp into that nature. If you look closer to screen there and you get to the electrode arm, it's a little different than the SevenExcellence, but this is very ergonomically capable. Basically take your thumb, turn this here, and you can go down into your buffers, if you do pH calibrations, which is recommended before any shift or each day, you're getting ready to take pH measurements of your samples. We can scroll right back up. And of course, you always want to remember to keep a handy bottle of distill water. You want to rinse your electro pull it out of that electro holder here. And in between, you want to remove the wetting cap as well, to the wetting cap is shipped with each electrode, just kind of twist this off and best practice is you don't want to throw this away as well. You want to use this for a long-term storage each day when you're done, you want to store your electrode with 3 molar KCL. So the tip of the sensing head does not dry out, you don't want to touch it with your fingers. You don't want to wipe that membrane as well, too. It can sure always have a handy dandy waste container here for each use, after each buffer, after each sample, just for best practices. So there's no cross contamination. After you've taken said pH calibrations, you can just swivel the arm over, and you can actually go down and take a pH measure into your sample. There's also what I want to point out to you here, if you look at the front of the SevenDirect meter, it has an indication bar -- a green indication bar, that bar lets you know that this instrument is ready to take measurements, is ready to go. Everything has been -- calibrations has been complete. You can move on to your next steps of your measurement of your day of your laboratory practices. Other things to consider, on the back of the meter, there's a close housing component to prevent from any kind of dust or spills getting into the back into the plug-in areas of the instrumentation as well. As mentioned in the webinar as far as electro best practices, this is a in-live Expert Pro, which is considered a 3-in-1 electrode compensate for pH mobile and a built-in temperature thermometer. That's pretty rugged and durable, it's a nonrefillable electrode. So once this electrode used life has been used, you just want to throw this out and order a new one. This is considered a consumable typical electrode life recommended by Mettler-Toledo is anywhere from 6 months to 2 years with the average being about one year as long as you're doing good electrode handling. That goes fresh buffers, fresh storage solution, handling with care, a lot of electrodes are made with glass, the glass body and some of them are refillable. You want to make sure you're not banging them around. If there are air bubbles, you can't shake them to get the air bubbles out, so you can have a consistent measurement and -- quick measurement results basically. The other thing to consider is Mettler-Toledo uses our e-commerce store any time you need to buy fresh buffers, fresh storage solutions, things that you will buy on a regular basis. We make it a seamless process where you can have some or more account and you can go through, and you can just order routinely on a regular basis every month, every few months, whenever you need those consumables, you can track your shipments, and you can make sure you're never going without buffers or storage solutions at that time. We offer the SevenDirect meter, the base meter and the stand, we offer it in different kit versions. So if you're just measuring pH only, you can order a pH only kit that comes with an electrode, the specific electrode for your application type. We offer connectivity only. We offer a pH and ion if you're measuring a specific ions. We offer the meter in those kit versions as well, too. And then we offer 1 version that has both pH and conductivity in the same base meter. It's not as modular as SevenExcellence, but can simultaneous measure pH and conductivity. You can always reach out to your local Mettler-Toledo service rep and they can put you in touch with us so we can go over your application specific needs as well as any troubleshooting for your pH measurements. With that being said, I'm going to open it up to any kind of questions you may have.

Matt, it's Jason. I've been addressing some of the questions on the chat. So as Matt mentioned, if anybody has any other questions, we'd be happy to address.

Keep in mind, if you don't have any questions that occur right now, you can always reach us through 1-800-METTLER. You can go through our website. You can submit inquiries if you're interested in our meters, our electrodes, if you need tech support assistance, service on our instruments, just let us know. We're always happy to help. We have a tech support group that is here Monday through Friday as well. You can always call 1-800-METTLER and can get in touch with them or one of us reps as well. And we cover all across the United States.

We do have a question in a chat from Wendy. Wendy mentions how do you know when the pH probe is bad. In most cases, it will have a very low slow percentage and have a very hard time calibrating your solutions. So typically, once you get in the slopes in the low 90s, upper 80s, it has a harder time establishing and recognizing the pH calibration buffers. Another question we have from Adriana. It was mentioned not to wipe off the junction. What's the best way to clean up the junction if you're testing things like creams and gels. And that situation typically a warm water or warm deionized water to help clear that junction. If you do have samples of protein in them. We recommend rinsing with the pepsin HCL solution that we offer through their customers that work with a lot of proteinaceous samples. We also have a pH theory guidance available, should be through our website. Feel free to request it as well. And I also put in the chat, electrodes.net. It's a good resource. You could type in your sample type, your sample characteristics, and I could give you a few recommendations for probes. Questions from Olga for the calibration with which buffer is better to start with acidic or basic. The meters have automatic buffer recognition. So when you're in calibration mode, it will know if you're in 4.01, 7 or 10.01. There's not necessarily a rigid rule to it, but I do know some folks like to start with 7 because that basically sets the meter to 0, right? We get the first offset value and then they go to 4, then they go to 10. But I don't think that's a hard and fast rule. Question from James, what's the concentration of the pepsin rinse? I don't have that in front of me now, but I could certainly pull it for you if you want to send me an e-mail, for my e-mail address in the chat. Question from Nicolas. When you're talking about cleaning specifically for working with proteins, does that apply to individual or free immuno acids as well? Yes, anything that's proteinaceous in nature could tend to clog electrodes over time. And please note that we do have Tris compatible probes, and Tris is certainly important in biological samples, hitting cell cultures and things like that. The website for the probe selection is electrodes.net. Christine, can you go over a common problem with pH measurement setup that was used for the promotion of the webinar. I believe there are 5 issues in that video. Unfortunately, I'm not familiar with that video, but I'd be happy to address them now or off-line as well. If you want to send me an e-mail, jason.berns@mt.com. Wendy has a question, What's the pH accurate measurement range. Depends on the probe. We do have some probes that perform better at higher alkaline levels or lower acidic levels. But typically, once you consider the air of the probe, the buffers, the system in place, we should look for an accuracy of plus or minus 0.05 pH units. Victor asks, which is the right buffer level for calibration. It depends on your sample. We actually recommend bracketing on either side with a calibration of what your sample is. So for -- if you want to measure a sample, you assume to be 5, that we recommend a calibration at 7 and 4. If you introduce a 10, it can influence how that probe behaves. It's also segmented and linear calibration. Segmented is recommended mode because it draws a straight line between 4 and 7 and then a separate line from 7 to 10. Shika asked, is there a preferred temperature for the best operation of the meters. Typically, lab temperature, room temperature is fine for the meters anywhere from 18 through, say, 25 degrees Celsius. The important thing is though that we have the probe, temperature matching your sample, temperature as close as possible. If they're different, then you'll take longer to get a reading because the probe is either trying to warm up or cool down and waiting for a stable temperature reading. What was the type of electrode used in the demo? Matt, if you could address that, I'm not sure which one that was?