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Combat food fraud: Meet Misa

Combat food fraud: Meet Misa

What’s on your plate?

Food fraud is an ever-present danger around the world. Despite increased regulations, huge scandals still occur regularly, such as deliberately tainted infant formula (2008), or the horse meat affair in the UK due to improper labelling (2013). Other more common examples include the adulteration of highly valued items with lower cost substitutes, or the illegal enhancement of color in foods and beverages with unsafe dyes.

As the population continues to increase, driving the demand for high quality food and beverage choices, so will the amount of food fraud cases. Only a concerted effort to test foodstuffs more frequently in an efficient manner along the supply chain with accurate and precise analytical techniques will bring these cases to light before more people come to harm.

Misa to the rescue

Meet the newest addition to the Metrohm Instant Raman Analyzer family: Misa, the Metrohm Instant SERS Analyzer. Misa is fast, smart, and portable with powerful algorithms that simplify high-tech analyses for non-technicians. Misa is designed with safety in mind, purposefully designed to detect illicit drugs and food additives in complex matrices.

The SERS Principle

Surface Enhanced Raman Scattering (SERS) is an extension of Raman. Perhaps you read in my previous blog post about Raman spectroscopy that «If you can see it, Raman can ID it»… well, SERS amplifies the Raman signal of trace analytes, making it an extremely sensitive method for «ID when you can’t see it.»

When SERS-active analytes adsorb to silver or gold nanoparticles, their Raman signal is enhanced as much as a million-fold, providing incredibly sensitive detection abilities.

SERS is used in biosensor applications, including single-cell sensing, antibody detection, and pathogen monitoring. It can be used to detect chemical warfare agents and illicit drug laboratory residues. Additionally, SERS is a particularly powerful technique for detecting trace contaminants in foodstuffs such as antibiotics fungicides, pesticides, herbicides, illicit dyes, and other additives.

If you know ID Kit for Mira DS, then you already know a little about SERS. SERS is an «enhancement» technique to Raman that enables detection of trace materials. For example, ID Kit was developed as a method for identifying heroin and fentanyl in street drug samples. The cutting agents and added stimulants that constitute the bulk of street heroin fluoresce under investigation with Raman and overwhelm the signal coming from heroin. SERS sees right through the cutting agents and identifies the drug.

Overlaid Raman and SERS spectra demonstrating the ability of SERS to detect the active ingredient in street heroin.

Another example of how Raman and SERS complement each other can be seen with Yaba, a common street drug in southeast Asia. Yaba is a red tablet that contains significant caffeine with a small amount of methamphetamine. When a red Yaba tablet is analyzed with Raman, caffeine and the red dye in the coating are the primary identification targets. This makes sense, because Raman is very good at identifying bulk materials.

However, when a Yaba tablet is subjected to SERS analysis, the story is very different (reminder: these are both also capabilities of Mira DS!) Only SERS can ID the methamphetamine in Yaba and complete the story.

Protecting Consumer Safety with Misa

Consumer safety relies on the ability of food inspectors to detect unwanted additives and assure the quality of the products. Trace detection of food adulterants is traditionally very involved laboratory work, using HPLC, GC/MS, and other techniques requiring extensive sample preparation and scientific training. Misa is designed to simplify food testing, from sample preparation, to sharing results.

The unique capabilities of Misa and SERS analysis in food testing deserve some explanation. Raman is used in food testing in some incredible ways: identifying counterfeit honey, distinguishing scotch from different producers, discriminating between very similar sugars, even making a distinction between grass- and grain-fed beef. However, these are bulk, inherent qualities of a food.

Looking for trace levels of pesticides is a very different science. A successful SERS analyte must interact with nanoparticles—target molecules with amine, carboxyl, and thiol groups often have the required interaction. Fortunately, many food additives fit this definition. Metrohm Raman sponsored a year-long study to identify 82 different food adulterants that can be successfully detected with our SERS substrates. That was just the beginning.

Are you looking for applications suitable for Misa? Check out our free selection of application notes available on the Metrohm website: 

Additionally, reference spectra for several other analytes can be obtained by contacting your local Metrohm  sales organization. 

The next step was to determine the foods which were typically treated with these illicit substances, then how to simplify sample preparation for potentially demanding food matrices. Metrohm Raman is taking two different approaches to this challenge. First, Misa will be released with 17 different «real world» food safety applications (click to download):

Misa is a unique instrument, which is reflected in this broad collection of Application Notes (AN). In addition to standard spectra and experiments, each AN includes a special section titled «Field Test Protocol». Briefly, the Field Test Protocol guides any user through a complete experiment using Misa and the tools in the ID Kits. ID Kits for Misa contain dedicated SERS substrates, in addition to the basic tools required for field testing. These, combined with companion Operating Procedures included on Misa, make food safety testing accessible to anyone, anywhere.

Our second approach to application development for Misa is a very interactive process with our users as we identify the target and food matrix, provide standard spectra for library building, advise sample preparation, and help to optimize results. This approach acknowledges that food is different around the world, adulterants vary, and concerns may be localized. These ANs that accompany Misa at release are intended to give the user an idea of how to use SERS and when it is a useful technique for detection of food contaminants, but custom applications will certainly increase demand for Misa.

Metrohm Raman is excited to introduce you to Misa. Misa has all of the qualities that you appreciate about Mira—intuitive user interface, simple guided workflow, and smart attachments to facilitate onsite testing by non-chemists. Our approach to simplifying food testing includes libraries, dozens of reference spectra, and developed applications targeting food adulterants.

Visit our website

and discover more about how Misa can help the fight against food adulteration scandals.

Post written by Dr. Melissa Gelwicks, Technical Writer at Metrohm Raman, Laramie, Wyoming (USA).

Comprehensive water analysis: combining titration, IC, and direct measurement in one setup

Comprehensive water analysis: combining titration, IC, and direct measurement in one setup

If you perform water analyses on a regular basis, then you know that analyzing different parameters for drinking water can be quite time-consuming, expensive, and it requires significant manual labor. In this article, I’d like to show you an example of wider possibilities in automated sample analysis when it comes to combining different analytical techniques, especially for our drinking water.

Water is the source and basis of all life. It is essential for metabolism and is our most important foodstuff.

As a solvent and transporting agent it carries not only the vital minerals and nutrients, but also, increasingly, harmful pollutants, which accumulate in aquatic or terrestrial organisms.

Within the context of quality control and risk assessment, there is a need in the water laboratory for cost-effective and fast instruments and methods that can deal with the ever more complex spectrum of harmful substances, the increasing throughput of samples, and the decreasing detection limits.

Comprehensive analysis of ionic components in liquid samples such as water involves four analytical techniques:

  • Direct measurement
  • Titration
  • Ion chromatography
  • Voltammetry

Each of these techniques has its own particular strengths. However, applying them one after the other on discrete systems in the laboratory is a rather complex task that takes up significant time.

Back in 1998, Metrohm accepted the challenge of combining different analytical techniques in a single fully automated system, and the first TitrIC system was introduced.

What is TitrIC?

The TitrIC system from Metrohm combines direct measurement, titration, and ion chromatography in a fully automated system.

Direct measurements include temperature, conductivity, and pH. The acid capacity (m and p values) is determined titrimetrically. Major anions and cations are quantified by ion chromatography. Calcium and magnesium, which are used to calculate total hardness, can be determined by titration or ion chromatography.

The results are displayed in a common table, and a shared report is given out at the end of the analysis. All methods in TitrIC utilize the same liquid handling units and a common sample changer.

For more detailed information about the newest TitrIC system, which is available in two predefined packages (TitrIC flex I and TitrIC flex II), take a look at our informative brochure:

Efficient: Titrations and ion chromatography are performed simultaneously with the TitrIC flex system.

Figure 1. Flowchart of TitrIC flex II automated analysis and data acquisition.

How does TitrIC work?

Each water sample analysis is performed fully automated at the push of a button—fill up a sample beaker with the sample, place it on the sample rack, and start the measurement. The liquid handling units transfer the required sample volume (per measurement technique) for reproducible results. TitrIC carries out all the work, and analyzes up to 175 samples in a row without any manual intervention required, no matter what time the measurement series has begun. The high degree of automation reduces costs and increases both productivity and the precision of the analysis.

Figure 2. The Metrohm TitrIC flex II system with OMNIS Sample Robot S and Dis-Cover functionality.

To learn more about how to perform comprehensive water analysis with TitrIC flex II, download our free application note AN-S-387:

Would you like to know more about why automation should be preferred over manual titration? Check out our previous blog post on this topic:

Calculations with TitrIC

With the TitrIC system, not only are sample analyses simplified, but the result calculations are performed automatically. This saves time and most importantly, avoids sources of human error due to erroneously noting the measurement data or performing incorrect calculations.

Selection of calculations which can be automatically performed with TitrIC: 

  • Molar concentrations of all cations
  • Molar concentrations of all anions
  • Ionic balance
  • Total water hardness (Ca & Mg)
  • … and more

Ionic balances provide clarity

The calculation of the ion balance helps to determine the accuracy of your water analysis. The calculations are based on the principle of electro-neutrality, which requires that the sum in eq/L or meq/L of the positive ions (cations) must equal the sum of negative ions (anions) in solution.

TitrIC can deliver all necessary data required to calculate the ion balance out of one sample. Both anions and cations are analyzed by IC, and the carbonate concentration (indicative of the acid capacity of water) is determined by titration.

If the value for the difference in the above equation is almost zero, then this indicates that you have accurately determined the major anions and cations in your sample.

Advantages of a combined system like TitrIC

  • Utmost accuracy: all results come from the same sample beaker

  • Completely automated, leaving analysts more time for other tasks

  • One shared sample changer saves benchtop space and costs

  • Save time with parallel titration and IC analysis

  • Flexibility: use titration, direct measurement, or IC either alone or combined with the other techniques

  • Single database for all results and calculation of the ionic balance, which is only possible with such a combined system, and gives further credibility to the sample results

Even more possibility in sample analysis

TitrIC has been developed especially for automated drinking water analysis but can be adapted to suit any number of analytical requirements in food, electroplating, or pharmaceutical industries. Your application determines the parameters that are of interest.

If the combination of direct measurement, titration, and IC does not suit your needs, perhaps a combination of voltammetry and ion chromatography in a single, fully automatic system might be more fitting. Luckily, there is the VoltIC Professional from Metrohm which fulfills these requirements.

Check out our website to learn more about this system:

As you see, the possibility of combining different analysis techniques is almost endless. Metrohm, as a leading manufacturer of instruments for chemical analysis, is aware of your analytical challenges. For this reason, we offer not only the most advanced instruments, but complete solutions for very specific analytical issues. Get the best out of your daily work in the laboratory!

Discover even more

about combined analytical systems from Metrohm

Post written by Jennifer Lüber, Jr. Product Specialist Titration/TitrIC at Metrohm International Headquarters, Herisau, Switzerland.

Determining the total sulfite in food and beverages: faster and easier than ever

Determining the total sulfite in food and beverages: faster and easier than ever

The chances are good that if you’re reading this, you are an analytical chemist or somehow connected to the food science sector. Maybe you have had the lucky experience of measuring sulfite (SO32-) before in the laboratory. I certainly have, and the adventure regarding tedious sample preparation and proper measurement of such a finicky analyte still haunts me today, years later.

Why sulfite?

Sulfite is a preservative added to a vast range of foods and beverages to prevent browning or oxidation. Some individuals are sensitive to sulfite additives and may experience a range of allergic reactions. Therefore, both the U.S. Food and Drug Administration (FDA) and European Union (EU) laws require that the presence of sulfites be declared on food labels when the concentration exceeds 10 mg/L.

To put this into perspective, an Olympic size swimming pool can hold about 2,500,000 liters, meaning anything beyond 25 kilograms (the average mass of one young child!) would need to be reported.

So, which foods contain sulfite?

Many foods and beverages contain sulfite – whether added to prolong the freshness, or occurring naturally as a byproduct from processes like fermentation. Typically, the first things that come to mind are wine, beer, or dried fruit snacks. However, many pickled and otherwise preserved items such as sauerkraut, canned fruits and vegetables, and even frozen foods contain significant levels of sulfites. Processed meats, several condiments, and some prepared doughs are also high on the list of offenders, so beware at your next picnic!

If you think you may be sensitive to sulfites, don’t forget to check the nutrition facts, and try to avoid such foodstuffs.

How is sulfite usually measured?

Several analytical methods exist to measure sulfite in food and beverages, however they suffer from repeatability issues, and can be quite cumbersome to perform.

Traditionally, the optimized Monier-Williams (OMW) AOAC Official Method 990.28 was used for quantification of sulfite in most foodstuffs, but the method detection limit now lies at the regulatory labeling threshold. Automated discrete analysis methods have been reported for sulfite analysis, but they are limited by their strong dependence on sample matrix type. Therefore these methods are less than ideal for laboratories where sulfite analysis is required for a wide variety of food and beverage products.

Methods based on ion chromatography (IC) with conductivity detection exhibit a lack of selectivity combined with an extended analysis time due to separation challenges. A newer method developed by AOAC (Method 990.31) focuses on the use of ion-exclusion chromatography followed by electrochemical (amperometric) detection of samples.

Another issue arises concerning the sensitivity of the detector. After a few injections, fouling from contaminants rapidly decreases the electrode sensitivity. Frequent reconditioning of the working electrode is necessary due to a rising background and baseline noise, and can be accomplished in a couple of ways. Manual polishing and utilizing pulsed amperometric detection (PAD) pulse sequences are the most common choices to recondition the surface of the working electrode, while other methods opt for disposable electrodes to avoid this step altogether.

What has improved?

Metrohm has filed a patent for an innovative, fast, and accurate ion chromatographic (IC) method based on direct current (DC) mode electrochemical detection. It works with the implementation of a unique working electrode conditioning function (patent pending) in the newest version of chromatographic software (MagIC Net 3.3) offered by Metrohm. A great diversity of food and beverage products were analyzed with sulfite recovery values near 100% in all cases. Using a single, robust chromatographic method, any sample can be treated identically, saving time and making laboratory work much easier.

Sample of garlic analyzed for sulfite content (spiked: red, unspiked: black). Recovery was calculated at 100%.
(Click to enlarge)

No matter what type of sample (solid, liquid), the preparation steps are nearly identical, and much simpler to perform than ever before. Additionally, the retention time of sulfite in the method does not shift. This saves even more time for analysts as they do not have to reprocess data. Since the electrode is automatically reconditioned after each analysis, results are both reliable and reproducible. Waste from disposable electrodes is reduced, as well as costs incurred by the materials and excess working hours which would generally be spent performing other manual steps. This is truly a win-win situation for food analysis!

Benefits to QC laboratories and beyond

In real terms, this improved method allows for up to 10x the throughput of samples compared to conventional methods. Previously, the contract laboratories involved in this study could measure 5 samples, with 2 analysts per 8-hour shift (15 samples per 24 hours, if you like). With our patent-pending technique, at 10 minutes per sample, including fully automatic regeneration of the electrode surface, this allows for up to 144 samples to be analyzed every day.

Whether you work in the food and beverage industry, wastewater analysis, or in daily analytical laboratory work, you can appreciate the numerous benefits this method offers. Robustness, reproducibility, time savings, cost savings, and a simpler procedure for sample preparation across the board – are you interested? With our expertise in ion chromatography as well as electrochemistry, among other techniques, Metrohm is able to offer such cutting edge methods for the most challenging applications.

Want to learn more?

Download our free Application Note:

Sulfite determination in food and beverages applying amperometric detection

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

Special thanks are given to Miguel Espinosa, Product Manager Ion Chromatography, at Metrohm Hispania (Madrid, Spain) for his assistance in providing the laboratory data for the study.