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Introduction to Analytical Instrument Qualification – Part 2

Introduction to Analytical Instrument Qualification – Part 2

Welcome back to our blog, and happy 2021! We hope that you and your families had a safe and restful holiday season. To start the year, we will conclude our introduction to Analytical Instrument Qualification. 

Metrohm’s approach to Analytical Instrument Qualification (AIQ)

Metrohm’s answer to Analytical Instrument Qualification is bundled in our Metrohm Compliance Services. The most thorough level of documentation offered for AIQ is the IQ/OQ.

Metrohm IQ/OQ documentation provides you with the required documentation in strict accordance to the major regulations from the USP, FDA, GAMP, and PIC/S, allowing you to document the suitability of your Metrohm instruments for your lab’s specific intended use.

With our test procedures (described later in more detail), we can prove that the hardware and software components function correctly, both individually and as part of the system as a whole. With Metrohm’s IQ/OQ, you are supported in the best possible way to integrate our systems into your current processes.

Our high quality documentation will have you «audit ready» all the time.

The flexibility of a modular document structure

Depending on the environment you work in and your specific demands, Metrohm can offer a tailored qualification approach thanks to documentation modularity. If you need a lower level of qualification, only the required modules can be executed. Our documentation consists of different modules, each of which documents the identity of the Metrohm representative along with the qualification reviewer, combined with the details of each instrument, software, and document involved in the qualification.  Thanks to this, each module is independent, which guarantees both full traceability and reliability for your system setup.

Cost-effective qualification from Metrohm

Metrohm supports you by implementing a cost-effective qualification process, depending upon your requirements and the modules needed. This means that a qualification is not about performing unnecessary actions, qualification is about completing the required work.

The risk assessment analysis defines the level of qualification needed and based on it, we focus on testing only what needs to be tested. In case you relocate your device to another lab, which qualification steps (DQ, IQ, OQ, PQ) are really needed in order to fulfill your requirements? Contact your local Metrohm expert for advice on this matter.

A complete Metrohm IQ/OQ qualification includes…

Metrohm IQ/OQ documentation is based on the following documentation tree, beginning with the first module, the Master Document (MD), followed by the Installation Qualification (IQ) and eventually the Operational Qualification (OQ). The OQ is then divided again into individual component tests (Hardware and Software) and a holistic test to validate your complete system.

Master Document (MD)

Each qualification starts with the Master Document (MD) – the central organizing document for the AIQ procedures. It not only describes the process of installing and qualifying the instruments, but also the competence and education level of the qualifying engineer. The MD identifies all other components to be added to the qualification, resulting in a flexible framework on which to build up a set of documentation.

Installation Qualification (IQ)

Once the content of the documentation is defined in the MD, the Installation Qualification (IQ) follows. This set of documentation is designed to ensure that the instrument, software, and any accessories have been all delivered and installed correctly. The IQ protocol additionally specifies that the workplace is suitable for the analytical system as stipulated by Metrohm.

Operational Qualification (OQ)

After a correct installation comes the main part of the qualification: the Operational Qualification (OQ). In the first part of the OQ, the functionality of the single hardware components is tested and evaluated according to a set of procedures. This is to ensure that the instrument is working perfectly as designed, and is safe to use. Rest assured that you can rely on the expertise of our Metrohm certified engineers to conduct these comprehensive tests on your instruments using the necessary calibrated and certified tools.

The second part of the OQ consists of a set of Software Tests to prove that the installed Metrohm software functions correctly and reliably on the computer it was installed on. The importance of maintaining software in a validated state is also related to the data integrity of your laboratory. Therefore these software tests can be repeated periodically or after major changes. In particular, these functionality tests cover verifications on user management, database functionalities, backups, audit trail review, security policy, electronic signatures, and so on.

At Metrohm, we constantly work to improve our procedures and use state of the art tools and technologies.  For this reason, we have implemented a completely automated test procedure for validating the software of our new OMNIS platform. This ensures full integrity in the execution and delivers consistent results with a faster and completely error-free test execution. This innovative and automated software validation eliminates manual activities that are labor intensive and time consuming. This therefore expedites testing and removes the inefficiencies that plague the paper-based software validation.

Your benefit is clear: save valuable time and reduce unnecessary laboratory start-up activities during qualification. That’s time you can spend on other work in your lab!

Holistic Test (Performance Verification, PV)

Once each individual component has been separately tested, the performance of the system as a whole is proven by means of a holistic test (OQ-PV).

This includes a series of «wet-chemical» tests, performed using certified reference materials, to prove the system is capable of generating quality data, i.e. results that are accurate, precise, and above all fit for purpose. Based on detailed, predefined instructions (SOPs), a series of standard measurements are performed, statistically evaluated, and compared to the manufacturer’s specifications.

Differences between Performance Verification (PV) and Performance Qualification (PQ)

The Performance Verification (PV) is a set of tests offered by Metrohm in order to verify the fitness for purpose of the instrument. As mentioned in the previous paragraph, the PV includes standardized test procedures to ensure the system operates as designed by the manufacturer in the selected environment.

On the other hand, the Performance Qualification (PQ) is a very customer specific qualification phase (see the «4 Q’s» Qualification Phases found in Part 1). PQ verifies the fitness for purpose of the instrument under actual condition of use, proving its continued suitability. Therefore, PQ tests are defined depending on your specific analysis and acceptance criteria.

Now my questions to you—is your analytical instrument qualified for its intended use? Is your lab in compliance with the latest regulations for equipment qualification and validation? Get expert advice directly from your local Metrohm agency and request your quote for Metrohm qualification services today!

Check out our online material:

Metrohm Quality Service

Post written by Lara Casadio, Jr. Product Manager Service at Metrohm International Headquarters, Herisau, Switzerland.

«Analyze This»: 2020 in review

«Analyze This»: 2020 in review

I wanted to end 2020 by thanking all of you for making «Analyze This» – the Metrohm blog for chemists such a success! For our 60th blog post, I’d like to look back and focus on the wealth of interesting topics we have published this year. There is truly something for everyone: it doesn’t matter whether your lab focuses on titration or spectroscopic techniques, or analyzes water samples or illicit substances – we’ve got you covered! If you’re looking to answer your most burning chemical analysis questions, we have FAQs and other series full of advice from the experts. Or if you’re just in the mood to learn something new in a few minutes, there are several posts about the chemical world to discover.

We love to hear back from you as well. Leaving comments on your favorite blog posts or contacting us through social media are great ways to voice your opinion—we at Metrohm are here for you!

Finally, I wish you and your families a safe, restful holiday season. «Analyze This» will return on January 11, 2021, so subscribe if you haven’t already done so, and bookmark this page for an overview of all of our articles grouped by topic!

Stay healthy, and stay curious.

Best wishes,

Dr. Alyson Lanciki, Scientific Editor, Metrohm AG

Quickly jump directly to any section by clicking a topic:

Customer Stories

We are curious by nature, and enjoy hearing about the variety of projects where our products are being used! For some examples of interesting situations where Metrohm analytical equipment is utilized, read on.

From underwater archaeological research to orbiting Earth on the International Space Station, Metrohm is there! We assist on all types of projects, like brewing top quality beers and even growing antibiotic-free shrimp – right here in Switzerland.

Interested in being featured? Contact your local Metrohm dealer for details!


Metrohm is the global market leader in analytical instruments for titration. Who else is better then to advise you in this area? Our experts are eager to share their knowledge with you, and show this with the abundance of topics they have contributed this year to our blog.

For more in-depth information about obtaining the most accurate pH measurements, take a look at our FAQ about pH calibration or read about avoiding the most common mistakes in pH measurement. You may pick up a few tips!

Choose the best electrode for your needs and keep it in top condition with our best practices, and then learn how to standardize titrant properly. Better understand what to consider during back-titration, check out thermometric titration and its advantages and applications, or read about the most common challenges and how to overcome them when carrying out complexometric titrations

If you are interested in improving your conductivity measurements, measuring dissolved oxygen, or the determination of oxidation in edible fats and oils, check out these blog posts and download our free Application Notes and White Papers!

Finally, this article about comprehensive water analysis with a combination of titration and ion chromatography explains the many benefits for laboratories with large sample loads. The history behind the TitrIC analysis system used for these studies can be found in a separate blog post.

Karl Fischer Titration

Metrohm and Karl Fischer titration: a long history of success. Looking back on more than half a century of experience in KFT, Metrohm has shaped what coulometric and volumetric water analysis are today.

Aside from the other titration blog posts, our experts have also written a 2-part series including 20 of the most frequently asked questions for KFT arranged into three categories: instrument preparation and handling, titration troubleshooting, and the oven technique. Our article about how to properly standardize Karl Fischer titrant will take you step by step through the process to obtain correct results.

For more specific questions, read about the oven method for sample preparation, or which is the best technique to choose when measuring moisture in certain situations: Karl Fischer titration, near-infrared spectroscopy, or both?

Ion Chromatography (IC)

Ion chromatography has been a part of the Metrohm portfolio since the late 1980s. From routine IC analysis to research and development, and from stand-alone analyzers to fully automated systems, Metrohm has provided IC solutions for all situations. If you’re curious about the backstory of R&D, check out the ongoing series about the history of IC at Metrohm.

Metrohm IC user sitting at a laboratory bench.

Common questions for users are answered in blog posts about IC column tips and tricks and Metrohm inline ultrafiltration. Clear calculations showing how to increase productivity and profitability in environmental analysis with IC perfectly complement our article about comprehensive water analysis using IC and titration together for faster sample throughput.

On the topic of foods and beverages, you can find out how to determine total sulfite faster and easier than ever, measure herbicides in drinking water, or even learn how Metrohm IC is used in Switzerland to grow shrimp!

Near-Infrared Spectroscopy (NIRS)

Metrohm NIRS analyzers for the lab and for process analysis enable you to perform routine analysis quickly and with confidence – without requiring sample preparation or additional reagents and yielding results in less than a minute. Combining visible (Vis) and near-infrared (NIR) spectroscopy, these analyzers are capable of performing qualitative analysis of various materials and quantitative analysis of a number of physical and chemical parameters in one run.

Our experts have written all about the benefits of NIR spectroscopy in a 4-part series, which includes an explanation of the advantages of NIRS over conventional wet chemical analysis methods, differences between NIR and IR spectroscopy, how to implement NIRS in your laboratory workflow, and examples of how pre-calibrations make implementation even quicker.

A comparison between NIRS and the Karl Fischer titration method for moisture analysis is made in a dedicated article.

A 2-part FAQ about NIRS has also been written in a collaboration between our laboratory and process analysis colleagues, covering all kinds of questions related to both worlds.

Raman Spectroscopy

This latest addition to the Metrohm family expands the Metrohm portfolio to include novel, portable instruments for materials identification and verification. We offer both Metrohm Raman as well as B&W Tek products to cover a variety of needs and requirements.

Here you can find out some of the history of Raman spectroscopy including the origin story behind Mira, the handheld Raman instrument from Metrohm Raman. For a real-world situation involving methamphetamine identification by law enforcement and first responders, read about Mira DS in action – detecting drugs safely in the field.

Mira - handheld Raman keeping you safe in hazardous situations.

Are you looking for an easier way to detect food fraud? Our article about Misa describes its detection capabilities and provides several free Application Notes for download.

Process Analytics

We cater to both: the laboratory and the production floor. The techniques and methods for laboratory analysis are also available for automated in-process analysis with the Metrohm Process Analytics brand of industrial process analyzers.

Learn about how Metrohm became pioneers in the process world—developing the world’s first online wet chemistry process analyzer, and find out how Metrohm’s modular IC expertise has been used to push the limits in the industrial process optimization.

Additionally, a 2-part FAQ has been written about near-infrared spectroscopy by both laboratory and process analysis experts, which is helpful when starting out or even if you’re an advanced user.

Finally, we offer a 3-part series about the advantages of process analytical technology (PAT) covering the topics of process automation advantages, digital networking of production plants, and error and risk minimization in process analysis.

Voltammetry (VA)

Voltammetry is an electrochemical method for the determination of trace and ultratrace concentrations of heavy metals and other electrochemically active substances. Both benchtop and portable options are available with a variety of electrodes to choose from, allowing analysis in any situation.

A 5-part series about solid-state electrodes covers a range of new sensors suitable for the determination of «heavy metals» using voltammetric methods. This series offers information and example applications for the Bi drop electrode, scTrace Gold electrode (as well as a modified version), screen-printed electrodes, and the glassy carbon rotating disc electrode.

Come underwater with Metrohm and Hublot in our blog post as they try to find the missing pieces of the ancient Antikythera Mechanism in Greece with voltammetry.

If you’d like to learn about the combination of voltammetry with ion chromatography and the expanded application capabilities, take a look at our article about combined analysis techniques.

Electrochemistry (EC)

Electrochemistry plays an important role in groundbreaking technologies such as battery research, fuel cells, and photovoltaics. Metrohm’s electrochemistry portfolio covers everything from potentiostats/galvanostats to accessories and software.

Our two subsidiaries specializing in electrochemistry, Metrohm Autolab (Utrecht, Netherlands) and Metrohm DropSens (Asturias, Spain) develop and produce a comprehensive portfolio of electrochemistry equipment.

This year, the COVID-19 pandemic has been at the top of the news, and with it came the discussion of testing – how reliable or accurate was the data? In our blog post about virus detection with screen-printed electrodes, we explain the differences between different testing methods and their drawbacks, the many benefits of electrochemical testing methods, and provide a free informative White Paper for interested laboratories involved in this research.

Our electrochemistry instruments have also gone to the International Space Station as part of a research project to more efficiently recycle water on board spacecraft for long-term missions.

The History of…

Stories inspire people, illuminating the origins of theories, concepts, and technologies that we may have become to take for granted. Metrohm aims to inspire chemists—young and old—to be the best and never stop learning. Here, you can find our blog posts that tell the stories behind the scenes, including the Metrohm founder Bertold Suhner.

Bertold Suhner, founder of Metrohm.

For more history behind the research and development behind Metrohm products, take a look at our series about the history of IC at Metrohm, or read about how Mira became mobile. If you are more interested in process analysis, then check out the story about the world’s first process analyzer, built by Metrohm Process Analytics.

Need something lighter? Then the 4-part history of chemistry series may be just what you’re looking for.

Specialty Topics

Some articles do not fit neatly into the same groups as the rest, but are nonetheless filled with informative content! Here you can find an overview of Metrohm’s free webinars, grouped by measurement technique.

If you work in a regulated industry such as pharmaceutical manufacturing or food and beverage production, don’t miss our introduction to Analytical Instrument Qualification and what it can mean for consumer safety!


Finally, if you are more interested in reading articles related to the industry you work in, here are some compilations of our blog posts in various areas including pharmaceutical, illicit substances, food and beverages, and of course water analysis. More applications and information can be found on our website.

Food and beverages
All of these products can be measured for total sulfite content.

Oxidation stability is an estimate of how quickly a fat or oil will become rancid. It is a standard parameter of quality control in the production of oils and fats in the food industry or for the incoming goods inspection in processing facilities. To learn more about how to determine if your edible oils are rancid, read our blog post.

Determining total sulfite in foods and beverages has never been faster or easier than with our IC method. Read on about how to perform this notoriously frustrating analysis and get more details in our free LC/GC The Column article available for download within.

Measuring the true sodium content in foodstuff directly and inexpensively is possible using thermometric titration, which is discussed in more detail here. To find out the best way to determine moisture content in foods, our experts have written a blog post about the differences between Karl Fischer titration and near-infrared spectroscopy methods.

To determine if foods, beverages, spices, and more are adulterated, you no longer have to wait for the lab. With Misa, it is possible to measure a variety of illicit substances in complex matrices within minutes, even on the go.

All of these products can be measured for total sulfite content.

Making high quality products is a subject we are passionate about. This article discusses improving beer brewing practices and focuses on the tailor-made system built for Feldschlösschen, Switzerland’s largest brewer.

Pharmaceutical / healthcare

Like the food sector, pharmaceutical manufacturing is a very tightly regulated industry. Consumer health is on the line if quality drops.

Ensuring that the analytical instruments used in the production processes are professionally qualified is a must, especially when auditors come knocking. Find out more about this step in our blog post about Analytical Instrument Qualification (AIQ).

Moisture content in the excipients, active ingredients, and in the final product is imperative to measure. This can be accomplished with different analytical methods, which we compare and contrast for you here.

The topic of virus detection has been on the minds of everyone this year. In this blog post, we discuss virus detection based on screen-printed electrodes, which are a more cost-effective and customizable option compared to other conventional techniques.

Water analysis

Water is our business. From trace analysis up to high concentration determinations, Metrohm has you covered with a variety of analytical measurement techniques and methods developed by the experts.

Learn how to increase productivity and profitability in environmental analysis laboratories with IC with a real life example and cost calculations, or read about how one of our customers in Switzerland uses automated Metrohm IC to monitor the water quality in shrimp breeding pools.

If heavy metal analysis is what you are interested in, then you may find our 5-part series about trace analysis with solid-state electrodes very handy.

Unwanted substances may find their way into our water supply through agricultural practices. Find out an easier way to determine herbicides in drinking water here!

Water is arguably one of the most important ingredients in the brewing process. Determination of major anions and cations along with other parameters such as alkalinity are described in our blog post celebrating International Beer Day.

All of these products can be measured for total sulfite content.
Illicit / harmful substances

When you are unsure if your expensive spices are real or just a colored powder, if your dairy products have been adulterated with melamine, or fruits and vegetables were sprayed with illegal pesticides, it’s time to test for food fraud. Read our blog post about simple, fast determination of illicit substances in foods and beverages for more information.

Detection of drugs, explosives, and other illegal substances can be performed safely by law enforcement officers and first responders without the need for a lab or chemicals with Mira DS. Here you can read about a real life training to identify a methamphetamine laboratory.

Drinking water regulations are put in place by authorities out of concern for our health. Herbicides are important to measure in our drinking water as they have been found to be carcinogenic in many instances.

Post written by Dr. Alyson Lanciki, Scientific Editor at Metrohm International Headquarters, Herisau, Switzerland.

Introduction to Analytical Instrument Qualification – Part 2

Introduction to Analytical Instrument Qualification – Part 1

When talking about the subject of Analytical Instrument Qualification (AIQ), my first thought is of regulated industries, like pharmaceuticals and food. 

You may be wondering—Why do we need to qualify analytical instruments in this environment? Why does my titrando or my OMNIS system need such a service?

Consumer safety here is of paramount importance. Medicines that may represent a health hazard for patients or do not provide the intended therapeutic effect are undesirable and costly, therefore steps must be taken to safeguard the manufacturing process and prevent fatal implications. By qualifying the used analytical instruments, we can ensure that active ingredients and finished pharmaceutical products are manufactured in a safe environment.

In addition, procedures that prove instrument accuracy and repeatability are a must. Metrohm qualification procedures provide this documentation, fully traceable evidence which is also required for inspections and audits by regulatory authorities.

When auditors come knocking

In case an auditor observes any violations of the United States Food and Drug Administration (FDA) guidelines for example, this will be communicated in an inspectoral observation or a Warning Letter. If we look to pharmaceutical Warning Letters in the past, we can see that the FDA is mainly concerned with issues related to qualification and data integrity.

Some typical findings are e.g. the usage of an unqualified system, or the use of an instrument outside of the calibration range for which it was initially qualified. This proves the point that qualification of analytical instruments in regulated environments cannot be ignored.

Metrohm Compliance Services can help to prove the full data traceability of your qualification activities, simplifying your audit preparation and at the same time maintaining a constant state of inspection readiness for your laboratory.

Instruments in regulated environments need to be qualified periodically according to the main regulatory bodies. The United States Pharmacopeia (USP) is the leading pharmacopeia that has a general chapter dedicated to Analytical Instrument Qualification (AIQ), USP <1058>. Therefore, it has global significance, making laboratories subject to regulatory requirements either directly or indirectly. This is why Metrohm Compliance Services are based on this important chapter.

What is Analytical Instrument Qualification (AIQ) exactly?

As per USP <1058>, it is «the collection of documented evidence that an instrument performs suitably for its intended purpose.» This indicates that AIQ is the foundation for generating quality data with the needed data integrity. By using qualified instruments, you gain confidence in the validity of generated data and that your instrument meets specifications of regulatory standards.

AIQ is not a single activity, but a continuous process over the lifetime of the instrument. AIQ already starts before the instrument purchase with the formal writing of User Requirement Specifications (URS), where the lab’s requirements for a specific instrument are documented. And yes, for e.g. a fully equipped Metrohm Dual IC system as well as for a single Metrohm pH meter, there is the same need to document the laboratory requirements and its intended use.

After clarification of the intended use and the evaluation of the right technology, a Risk Assessment (RA) needs to be carried out to determine the required qualification strategy to prove the «fitness for purpose» of the purchased analytical instrument.

The extent of the next qualification stages depends on the outcome of the Risk Assessment. The following activities are grouped into four phases: Design Qualification (DQ), Installation Qualification (IQ), Operational Qualification (OQ), and Performance Qualification (PQ), the so-called «4 Q’s».

Whereas the DQ is the documented verification that the instrument specifications meet the laboratory requirements, the IQ provides the proof that the equipment has been installed properly. In the OQ phase, it’s demonstrated that the system operates correctly in the selected environment as per manufacturer specifications, while the PQ confirms that the instrument consistently performs according to your defined specifications.

During the lifecycle of the instrument, major repairs might be needed, it might be subject to major updates / upgrades, or it might even be transferred to another lab. In all of these cases, the original URS should be reviewed again and adjusted if necessary. The URS is a living document that can and must be changed and updated when needed. Based on a risk assessment analysis, it will then be defined what the qualification steps are that should be repeated after the needed changes (IQ, OQ, PQ).

Eventually the instrument’s life comes to an end, and we arrive at its retirement. This final step of the AIQ is often considered as the «forgotten child» of validation activities. To put this a bit more in perspective, consider when you make a new electronic purchase, such as a PC. The situation is similar to when a new analytical system is bought. It’s easier to focus on something new—concentrating on getting the training for its proper usage, and making sure it’s working correctly. We begin to ignore or forget that the old system is still there.

Therefore, decommissioning of an instrument is a critical part of the validation process that must also be very well documented. For the old system, a final system qualification might be necessary if required. Afterwards, all data have to be removed and stored in a safe location. It is extremely important to ensure that the data can be read from this location (data migration) for a number of years, depending on your retention procedures.

Support when and where you need it

The fact that users have responsibilities for the instrument qualification (USP <1058>) does not mean that all qualification activities must be conducted alone!

Metrohm supports you over the lifetime of your investment, from advising you during the purchase process to the first installation and qualification. Additionally, our IQ/OQ documentation provides you the required documentation in strict accordance with the current regulations. To ensure your Metrohm device remains in a qualified state, we offer requalification services at scheduled intervals as specified in your requirements, to guarantee the accuracy and precision of your system over its lifetime. 

An advantage of relying on Metrohm as the manufacturer of your analytical instruments is that we have all the necessary experience for performing IQ/OQ procedures. Most importantly, our certified service engineers bring along all calibrated and certified reference instruments that are required for the qualification. To ensure the quality of Metrohm Service is maintained, our service engineers undergo compulsory re-training on a regular basis according to a globally standardized program.

Buying Metrohm equipment is the first step to success, but maintaining it in a qualified state is the key! Just contact your local Metrohm dealer and let us handle the rest.

For more details about which qualification phases can be fully handled by Metrohm and where we can support you, read Part 2!

Check out our online material:

Metrohm Quality Service

Post written by Lara Casadio, Jr. Product Manager Service at Metrohm International Headquarters, Herisau, Switzerland.

Frequently asked questions in near-infrared spectroscopy analysis – Part 2

Frequently asked questions in near-infrared spectroscopy analysis – Part 2

Whether you are new to the technique, a seasoned veteran, or merely just curious about near-infrared spectroscopy (NIRS), Metrohm is here to help you to learn all about how to perform the best analysis possible with your instruments.

In this series, we will cover several frequently asked questions regarding both our laboratory NIRS instruments as well as our line of Process Analysis NIRS products.

Did you miss Part 1 in this series? Find it here!

1. What are typical detection limits for liquid samples and for solid samples?

The detection limit varies depending on the substance analyzed, the complexity of the sample matrix, and the sensitivity of both the reference and NIR technology used. NIR spectroscopy systems using dispersive technology are the most sensitive. Using such a system to analyze a simple sample in which the parameter of interest is a strong absorber will allow low detection limits.

For example, water in solvents can be detected down to about 10 mg/L in both offline and online/inline measurements. For more complex matrices (e.g., solids and slurries), detection limits are about 1000 mg/L (0.1%).

For more information about the differences between solid and liquid samples for NIRS analysis, as well as the different methods best suited for such matrices, read our blog post «Benefits of NIR spectroscopy: Part 1» here!

2. What accuracy can I achieve with NIR spectroscopy?

The accuracy of a near-infrared spectroscopic method depends on the accuracy of the reference/primary method. A highly accurate primary method will result in the development of a highly accurate NIR method, while a less accurate primary method lowers the accuracy of the related NIR method. This is because the NIR data and primary data are correlated in the prediction model. A good prediction model will have approximately 1.1x the accuracy of the primary method over the prediction range.

The development of prediction models has been described in detail in our previous blog article: «Benefits of NIR spectroscopy: Part 3».

3. How are instruments calibrated and how often do I need to recalibrate an instrument?

Instruments are calibrated using certified NIST standards. For dispersive systems measuring in reflection mode, NIST SRM 1920 standards are used to calibrate the wavelength / wavenumber axis. Certified reflection standards with a defined reflectance made of ceramic can be used to calibrate the absorbance axis.

In transmission mode, typically NIST SRM 2065 or 2035 are used for the wavelength / wavenumber calibration, and air for the absorbance axis.

A calibration should be performed after each hardware modification (e.g., lamp exchange) and annually as part of a service interval. Ideally, the spectroscopy software guides user through the complete calibration processes.

Find the calibration tools for your Metrohm NIRS instruments here!

Metrohm NIRS reflection standard, set of 2.

4. How do I validate my instrument and how frequently should validation be done?

The Metrohm NIRS DS2500 Solid Analyzer.

NIR spectroscopy software offers different tests to validate the performance of the instrument. The most common one is a basic performance test, which tests some crucial hardware parts as well as the wavelength/wavenumber calibration and the signal to noise (S/N) of the system.

For the regulated environment, further tests according to the USP <856> guidelines are typically implemented, including photometric linearity and noise at high and low light fluxes. Instrument performance tests should be performed on a regular basis, with the frequency depending on risk assessment.

5. What sample types or parameters are not suitable for analysis with NIR spectroscopy?

Samples containing a high amount of carbon black cannot be analyzed by NIR spectroscopy because carbon black absorbs almost all NIR light.

Further, most inorganic substances have no absorbance bands in the NIR spectral region and are therefore not suitable for NIR analysis.

Find out more about the molecules and functional groups which are active in the NIR region of the electromagnetic spectrum in our previous blog post: «Benefits of NIR spectroscopy: Part 2».

Carbon black is not a suitable sample to be measured by NIR technology.

Are you looking for more spectroscopy applications? Check out the Metrohm Application Finder to download free applications across a variety of industries!

6. My industrial process is full of harsh chemicals, so manual sampling is not desirable. Is it possible to perform inline NIR analysis in hazardous areas?

Yes, and we have the right solutions for you. Metrohm not only manufactures instruments for laboratory analysis, but we also cater to the industrial process world! Metrohm Process Analytics offers two versions of process NIRS systems: the NIRS Analyzer Pro and the NIRS XDS Process Analyzer, the latter being the ideal solution for hazardous environments.

Metrohm Process Analytics offers two lines of near-infrared spectroscopic process analyzers: the NIRS Analyzer PRO and the NIRS XDS Process Analyzer.

NIRS is a robust and extremely versatile method, which enables simultaneous, «real-time» monitoring of diverse process parameters with a single measurement. The use of fiber-optics in NIRS means that the process analyzer and measuring point can be spatially separated – even by hundreds of meters if required. In fact, remote monitoring can be achieved at large distances without significant impact to S/N ratios. This is a huge advantage in environments with challenging explosion protection requirements. Fiber-optic probes and flow cells can be placed in very harmful working environments, while the spectrometer and analysis PC remain safe and secure in a shelter. When a shelter is not available, the NIRS XDS Process Analyzer can be directly placed in the hazardous area (ATEX Zone 2 or Class1Div2).

Obtain «real-time» results of your process without the need to take samples, reduce the risks of handling chemicals, and increase your profitability. Download our free brochure here for more information about safe operation of NIRS process analyzers in hazardous areas!

7. How is the maintenance of a NIRS process analyzer performed?

Maintenance is easy, fast, and not necessary to perform very often. NIRS is a reagentless analytical technique, so the only consumable to be replaced is the lamp, which needs replacement once per year.

Compared to other techniques like chromatography  (e.g., GC, IC) or titration, and also because NIR spectroscopic analysis does not degrade samples, there is no chemical waste which is produced. Additionally, thanks to our all-in-one software, automatic performance tests are performed regularly to guarantee that the analyzer is operating according to process specifications. The instrument can be left in the process without any further operator involvement. 

Metrohm Process Analytics NIRS process analyzers are maintenance-free systems that have been designed to guarantee high uptimes and low operational costs.

Are you searching for more process NIRS applications? Check out the Metrohm Application Finder to download them for free!

Want to learn more about NIR spectroscopy and potential applications? Have a look at our free and comprehensive application booklet about NIR spectroscopy.

Download our Monograph

A guide to near-infrared spectroscopic analysis of industrial manufacturing processes

Post written by Dr. Nicolas Rühl (Product Manager Spectroscopy at Metrohm International Headquarters, Herisau, Switzerland) and Dr. Alexandre Olive (Product Manager Process Spectroscopy at Metrohm Applikon, Schiedam, The Netherlands).

Thermometric titration – the missing piece of the puzzle

Thermometric titration – the missing piece of the puzzle

Titration is a well-established analysis technique taught to each and every chemistry student. Titration is carried out in nearly every analytical laboratory either as manual titration, photometric titration, or potentiometric titration. In this blog entry, I would like to present an additional kind of titration you may  not have heard of before – thermometric titration – which can be considered the missing piece of the titration puzzle.

Here, I plan to cover the following topics:
  1. What is thermometric titration?
  2. Why consider thermometric titration?
  3. Practical application examples

What is thermometric titration?

At first glance, thermometric titration (TET) looks like a normal titration and you won’t see much (or any) difference from a short distance. The differences compared to potentiometric titration are in the details.

TET is based on the principle of enthalpy change (ΔH). Each chemical reaction is associated with a change in enthalpy which in turn causes a temperature change. During a titration, analyte and titrant react either exothermically (increase in temperature) or endothermically (decrease in temperature).

During a thermometric titration, the titrant is added at a constant rate and the change in temperature caused by the reaction between analyte and titrant is measured. By plotting the temperature versus the added titrant volume, the endpoint can be determined by a break within the titration curve. Figure 1 shows idealized thermometric titration curves for both exothermic and endothermic situations.

Figure 1. Illustration of exothermic and endothermic titration curves showing clear endpoints where the temperature of the solution changes abruptly.

What happens during a thermometric titration?

During an exothermic titration reaction, the temperature increases with the titrant addition as long as analyte is still present. When all analyte is consumed, the temperature decreases again as the solution equilibrates with the atmospheric temperature and/or due to the dilution of the solution with titrant (Figure 1, left graph). This temperature decrease results in an exothermic endpoint.

On the contrary, for an endothermic titration reaction, the temperature decreases with the titrant addition as long as analyte is still available. When all analyte is consumed, the temperature stabilizes or increases again as the solution equilibrates with the atmospheric temperature and/or due to the dilution of the solution with titrant (Figure 1, right graph). This temperature decrease results in an endothermic endpoint.

Knowing the absolute temperature, isolating the titration vessel, or thermostating the titration vessel is thus not required for the titration.

Figure 2. Metrohm’s maintenance-free Thermoprobe used for the reliable indication of thermometric endpoints.

In order to measure the small temperature changes during the titration, a very fast responding thermistor with a high resolution is required. These sensors are capable of measuring temperature differences of less than 0.001 °C, and allow the collection of a measuring point every 0.3 seconds (Figure 2). 

Visit the Metrohm website to learn more about the fast, sensitive Thermoprobe products available even for aggressive sample solutions.

If you would like to learn more about the theory behind TET, then download our free comprehensive monograph on thermometric titration.

Why consider thermometric titration?

Potentiometric and photometric titration are already well established as instrumental titration techniques, so why should one consider thermometric titration instead?


TET has the same advantages as any instrumental titration technique:
  • Inexpensive analyses: Titration instruments are inexpensive to purchase and do not have high running and maintenance costs compared to other instruments for elemental analysis (e.g., HPLC or ICP-MS).
  • Absolute method: Titration is an absolute method, meaning it is not necessary to frequently calibrate the system.
  • Versatile use: Titration is a universal method, which can be used to determine many different analytes in various industries.
  • Easy to automate: Titration can be easily automated, increasing reproducibility and efficiency in your lab.
In comparison to classical instrumental titration, thermometric titration has several additional advantages:
  • Fast titrations: Due to the constant titrant addition, thermometric titrations are very fast. Typically, a thermometric titration takes 2–3 minutes.
  • Single sensor: Regardless of the titration reaction (e.g., acid-base, redox, precipitation, …), the same sensor (Thermoprobe) can be used for all of them.
  • Maintenance-free sensor: Additionally, the Thermoprobe is maintenance free. It requires no calibration or electrolyte filling and can simply be stored dry.
  • Less solvent: Typically, thermometric titrations use 30 mL of solvent or even less. The small amount of solvent ensures that the dilution is minimized, and the enthalpy changes can be detected reliably. As a side benefit, less waste is produced.
  • Additional titrations possible: Because enthalpy change is universal for any chemical reaction, thermometric titration is not bound to finding a suitable color indicator or indication electrode. This allows the possibility of additional titrations which cannot be covered by other kinds of titration.
  • Easier sample preparation: As TET uses higher titrant concentrations it is possible to use larger sample sizes, reducing weighing and dilution errors. Tedious sample preparation steps such as filtration can be omitted as well.
Figure 3. The Metrohm 859 Titrotherm with 801 Stirrer and notebook with tiamo™ software.

Learn more about the 859 Titrotherm system for the most reliable TET determinations on the Metrohm website.

Practical application examples

In this section I would like to present you some practical examples where TET can be applied.

Acid number and base number

The acid number (AN) and base number (BN) are two key parameters in the petroleum industry. They are determined by a nonaqueous acid-base titration using KOH or HClO4, respectively, as titrant.

During such determinations, very weak acids (for AN analysis) and bases (for BN analysis) are titrated with only small enthalpy changes. Using a catalytic indicator, these weak acids and bases can also be determined by TET.

ASTM D8045 describes the analysis of the AN by thermometric titration. The benefits of carrying out this titration are:

  • Less solvent (30 mL instead of 60 or 120 mL), meaning less waste
  • Fast titration (1–3 minutes)
  • No conditioning of the sensor

If you wish to learn more about how well the results of the AN determination according to ASTM D8045 correlate with ASTM D664, download our free White Paper WP-012 as well as our brochure below.

For more detailed information about the titration itself, download the free Application Bulletin AB-427 (AN) and Application Bulletin AB-405 (BN) below.


Using conventional titration, the salt content in foodstuff is usually determined based solely on the chloride content. However, foods usually contain additional sources of sodium, e.g. monosodium glutamate (also known as «MSG»). With TET it becomes possible to titrate the sodium directly, and thus to inexpensively determine the true sodium content in foodstuff, as stipulated in several countries.

If you wish to learn more about the sodium determination, watch our Metrohm LabCast video: «Sodium determination in food: Fast and direct thanks to thermometric titration».

Fertilizer analysis

Fertilizers consists of various nutrients, including phosphorus, nitrogen, and potassium, which are important for plant growth. TET enables the analysis of these nutrients by employing classical gravimetric reactions as the basis for the titration (e.g., precipitation of sulfate with barium). This allows for a rapid determination, without needing to wait hours for a result, as with conventional procedures based on drying and weighing the precipitate.

Nutrients which can be analyzed by TET include:
  • Phosphate
  • Potassium
  • Ammoniacal nitrogen
  • Urea nitrogen
  • Sulfate

Want to learn more about the analysis of fertilizers with thermometric titration? Download our free White Paper WP-060 on this topic. For more detailed information regarding the different fertilizer applications, check out the Metrohm Application Finder, or find a curated selection here.

Metal-organic compounds

Metal-organic compounds, such as Grignard reagents or butyl lithium compounds, are used for synthetizing active pharmaceutical ingredients (APIs) or manufacturing polymers such as polybutadiene. With TET, the analysis of these sensitive species can be performed rapidly and reliably by titrating them under inert gas with 2-butanol.

If you wish to learn more about this topic, check out our news article and download the free corresponding Application Note AN-H-142.

These were just a few examples about the possibilities of thermometric titration, to demonstrate its versatile use. For a more detailed selection, have a look at our Application Finder.

To summarize:

  • TET is an alternative titration method based on enthalpy change
  • A fast and sensitive Thermoprobe is used to determine exothermic and endothermic endpoints
  • Thermometric titration is a fast analysis technique providing results in less than 3 minutes
  • Thermometric titration can be used for various analyses, including titrations which cannot be performed otherwise (e.g., sodium determination)

I hope this overview has given you a better idea about thermometric titration – the missing piece of the titration puzzle.

For more information

Download our free Monograph:

Practical thermometric titrimetry

Post written by Lucia Meier, Technical Editor at Metrohm International Headquarters, Herisau, Switzerland.

Frequently asked questions in near-infrared spectroscopy analysis – Part 1

Frequently asked questions in near-infrared spectroscopy analysis – Part 1

Whether you are new to the technique, a seasoned veteran, or merely just curious about near-infrared spectroscopy (NIRS), Metrohm is here to help you to learn all about how to perform the best analysis possible with your instruments.

In this series, we will cover several frequently asked questions regarding both our laboratory NIRS instruments as well as our line of Process Analysis NIRS products.

1. What is the difference between IR spectroscopy and NIR spectroscopy?

IR (infrared) and NIR (near-infrared) spectroscopy utilize different spectral ranges of light. Light in the NIR range is higher in energy than IR light (Figure 1), which affects the interaction with the molecules in a sample.

Electromagnetic Spectrum
Figure 1. The electromagnetic spectrum.

This energy difference has both advantages and disadvantages, and the selection of the ideal technology depends very much on the application. The higher energy NIR light is absorbed less than IR light by most organic materials, broadening the resulting bands and making it difficult to assign them to specific functional groups without mathematical processing.

However, this same feature makes it possible to perform analysis without sample preparation, as there is no need to prepare very thin layers of analyte or use ATR (attenuated total reflection). Additionally, NIRS can quantify the water content in samples up to 15%.

Want to learn more about how to perform faster quality control at lower operating costs by using NIRS in your lab? Download our free white paper here: Boost Efficiency in the QC laboratory: How NIRS helps reduce costs up to 90%.

The weaker absorption of NIR light leads to using long pathlengths for liquid measurements, which is particularly helpful in industrial process environments. Speaking of such process applications, with NIR spectroscopy, you can use long fiber optic cables to connect the analyzer to the measuring probe, allowing remote measurements throughout the process due to low absorbance of the NIR light by the fiber (Figure 2).

Electromagnetic Spectrum
Figure 2. Illustration of the long-distance measurement possibility of a NIRS process analyzer with the use of low-dispersion fiber optic cables. Many sampling options are available for completely automated analysis, allowing users to gather real-time data for immediate process adjustments.

For more information, read our previous blog post outlining the differences between infrared and near-infrared spectroscopy.

2. NIR spectroscopy is a «secondary technology». What does this mean?

To create prediction models in NIR spectroscopy, the NIR spectra are correlated with parameters of interest, e.g., the water content in a sample. These models are then used during routine quality control to analyze samples.

Values from a reference (primary) method need to be correlated with the NIR spectrum to create prediction models (Figure 3). Since NIR spectroscopy results depend on the availability of such reference values during prediction model development, NIR spectroscopy is therefore considered a secondary technology.

Electromagnetic Spectrum
Figure 3. Correlation plot of moisture content in samples measured by NIRS compared to the same samples measured with a primary laboratory method.

For more information about how Karl Fischer titration and NIR spectroscopy work in perfect synergy, download our brochure: Water Content Analysis – Karl Fischer titration and Near-Infrared Spectroscopy in perfect synergy.

Read our previous blog posts to learn more about NIRS as a secondary technique.

3. What is a prediction model, and how often do I need to create/update it?

In NIR spectroscopy, prediction models interpret a sample’s NIR spectrum to determine the values of key quality parameters such as water content, density, or total acid number, just to name a few. Prediction models are created by combining sample NIR spectra with reference values from reference methods, such as Karl Fischer titration for water content (Figure 3).

A prediction model, which consists of sufficient representative spectra and reference values, is typically created once and will only need an update if samples begin to vary (for example after a change of production process equipment or parameter, raw material supplier, etc.).

Want to know more about prediction models for NIRS? Read our blog post about the creation and validation of prediction models here.

4. How many samples are required to develop a prediction model?

The number of samples needed for a good prediction model depends on the complexity of the sample matrix and the molecular absorptivity of the key parameter.

For an «easy» matrix, e.g., a halogenated solvent with its water concentration as the measurement parameter, a sample set of 1020 spectra covering the complete concentration range of interest may be sufficient. For applications that are more complex, we recommend using at least 40–60 spectra in order  to build a reliable prediction model.

Find out more about NIRS pre-calibrations built on prediction models and how they can save time and effort in the lab.

5. Which norms describe the use of NIR in regulated and non-regulated industries?

Norms describing how to implement a near-infrared spectroscopy system in a validated environment include USP <856> and USP <1856>. A general norm for non-regulated environments regarding how to create prediction models and basic requirements for near-infrared spectroscopy systems are described in ASTM E1655. Method validation and instrument validation are guided by ASTM D6122 and ASTM D6299, respectively.

Figure 4. Different steps for the successful development of quantitative methods according to international standards.

For specific measurements, e.g. RON and MON analysis in fuels, standards such as ASTM D2699 and ASTM D2700 should be followed.

For further information, download our free Application Note: Quality Control of Gasoline – Rapid determination of RON, MON, AKI, aromatic content, and density with NIRS.

6. How can NIRS be implemented in a production process?

Chemical analysis in process streams is not always a simple task. The chemical and physical properties such as viscosity and flammability of the sample streams can interfere in the analysis measurements. Some industrial processes are quite delicate—even the slightest changes to the process parameters can lead to significant variability in the properties of final products. Therefore, it is essential to measure the properties of the stream continuously and adjust the processing parameters via rapid feedback to assure a consistent and high quality product.

Figure 5. Example of the integration of inline NIRS analysis in a fluid bed dryer of a production plant.

Curious about this type of application? Download it for free from the Metrohm website!

The use of fiber optic probes in NIRS systems has opened up new perspectives for process monitoring. A suitable NIR probe connected to the spectrometer via optical fiber allows direct online and inline monitoring without interference in the process. Currently, a wide variety of NIR optical probes are available, from transmission pair probes and immersion probes to reflectance and transflectance probes, suitable for contact and non-contact measurements. This diversity allows NIR spectroscopy to be applied to almost any kind of sample composition, including melts, solutions, emulsions, and solid powders.

Selecting the right probe, or sample interface, to use with a NIR process analyzer is crucial to successful process implementation for inline or online process monitoring. Depending upon whether the sample is in a liquid, solid or gaseous state, transflectance or transmission probes are used to measure the sample, and specific fitting attachments are used to connect the probes to the reactor, tank, or pipe. With more than 45 years of experience, Metrohm Process Analytics can design the best solutions for your process. 

Visit our website to find a selection of free Application Notes to download related to NIRS measurements in industrial processes.

7. How can product quality be optimized with process NIRS?

Regular control of key process parameters is essential to comply with certain product and process specifications, and results in attaining optimal product quality and consistency in any industry. NIRS analyzers can provide data every 30 seconds for near real-time monitoring of production processes.

Figure 6. The Metrohm Process Analytics NIRS XDS Process Analyzer, shown here with multiplexer option allowing up to 9 measuring channels. Here, both microbundle (yellow) and single fiber (blue) optical cables are connected, with both a reflectance probe and transmission pair configured.

Using NIRS process analyzers is not only preferable for 24/7 monitoring of the manufacturing process, it is also extremely beneficial for inspecting the quality of raw materials and reagents. By providing data in «real-time» to the industrial control system (e.g., DCS or PLC), any process can be automated based on the NIRS data. As a result, downtimes are reduced, unforeseen situations are avoided, and costly company assets are safeguarded.

Furthermore, the included software on Metrohm Process Analytics NIRS instruments has a built-in chemometric package which allows qualification of a product even while it is still being produced. A report is then generated which can be directly used by the QC manager. Therefore, the product quality consistency is improved leading to potential added revenues.

Do you want to learn more about improving product quality with online or inline NIRS analysis? Take a look at our brochure!

In the next part, we cover even more of your burning questions regarding NIRS for lab and process measurements:

Want to learn more about NIR spectroscopy and potential applications? Have a look at our free and comprehensive application booklet about NIR spectroscopy.

Download our Monograph

A guide to near-infrared spectroscopic analysis of industrial manufacturing processes

Post written by Dr. Nicolas Rühl (Product Manager Spectroscopy at Metrohm International Headquarters, Herisau, Switzerland) and Dr. Alexandre Olive (Product Manager Process Spectroscopy at Metrohm Applikon, Schiedam, The Netherlands).