21st-Century Analysis

Wet chemistry analyses of protein and fat in food have a 200-year history. Olle Lundström examines whether there can be more improvements to these analyses

Johan Kjeldahl, Michel Eugène Chevreul, Jöns Jacob Berzelius and Franz Ritter von Soxhlet were four gentlemen that worked out definitions and methods to measure protein and fat. Their equipment was rudimentary, and they worked at home with both hot vapours and dangerous chemicals. Today few people, knowing the health aspects, would consider working under these conditions. However, they succeeded in giving us the characteristics of protein and fat.

Modern technology has given us automatic instruments to analyse these nutrients. Advances such as near infrared technology (NIR) provide fast and reliable measurements but they require correct calibrations to work. Calibrations require previous measurements for comparison, which is easy to solve when there are repeatable analyses. However, this is more challenging and even impossible when the sample composition is unknown. Therefore, NIR instruments are today used widely in food production but not always in research laboratories, where wet chemistry is still needed.

The growth of the NIR instrument market has been impressive, but unfortunately this has also led to that many believe that wet chemistry is not needed anymore. This is a belief not only among analysts but also among those companies involved in developing analytical wet chemistry instruments. Specific research and development in wet chemistry instruments has therefore been limited. Despite this, innovation in material science and information technology has continued
in other areas and new discoveries are now introduced in wet chemistry instruments.

New Materials

An example of a demanding wet chemistry environment is the Kjeldahl digestion, needed for protein determination. A Kjeldahl digestion uses up to 420°C to boil concentrated sulphuric acid, combining high temperature with strong acidity. Plastic material is challenging with the high temperature and at the same time, metal is sensitive to corrosion with the concentrated acid. Most solutions have historically used paint or enamel to protect a metal surface, but they have all their disadvantages regarding protection and durability. New production methods have recently changed this, by making old materials interesting again. Polytetrafluoreten (PTFE) was first used as a corrosion protection in the 1940s. It was used in the Manhattan Project for an atomic bomb as well as in the first non-stick pans from Tefal. For decades, it was an exclusive material used only when temperature was low enough. However, with new production methods, it is now possible to coat metals with more demanding and specific characteristics for heat and scratch resistance. Wet chemistry instruments can therefore be coated also for temperatures above 400°C!

New developments in materials have also made it possible to use coatings that give chemical resistance against both alkali and acid simultaneously. This is an important solution that can now be used in Kjeldahl distillation instruments.

Finally, and maybe a little surprising, development in the car industry has also provided innovations for the wet chemistry laboratory. The problem with a car travelling on dirty roads, causing corrosion on metal, is not that different from the harsh environment surrounding some wet chemistry instruments. Factories dedicated to supply the car industry with coated metal details are therefore now also coating metal for wet chemistry instruments.

New IT Solutions

Wet chemistry and the fundamental methods have not changed, but the information technology and our need to handle data have. Previously it was possible to use paper and pen to take notes and register results, but this is not always possible with new ISO standards and other legal requirements. Most laboratories now require results to be available in a digital format and traceability of activities.

Many wet chemistry instruments have been able to connect to computers, using USB sticks and similar means for a long time. With those solutions, it is possible to register weights and retrieve results. However, some manufacturers of wet chemistry instruments are now adding new solutions.

The ability to receive instrument alarm messages on a mobile phone, regardless of where the operator is located, is now technically possible. The technology itself is not new but previously this was an exclusive feature for large computer systems. The novelty is that this technology has been developed for wet chemistry instruments, including necessary apps on mobile phones.

Remote access to wet chemistry instruments provides increased capabilities for maintenance and help. Remote service has previously been exclusive to advanced and expensive computer systems, but new technology is also changing this.

New computer software, written specifically for wet chemistry laboratories, solves other challenges for a modern laboratory. Dedicated software can provide automatic integration between balances and instruments, automatic traceability according to regulations and a faster and simplified registration flow.

Specific technical solutions and material choices vary between different manufacturers. In common for all these new solutions are the possibilities they provide to laboratories. Safer, less maintenance and a better information flow are the new promises. This will help all laboratories using wet chemistry analysis.

Olle Lundström is managing director of Opsis LiquidLine

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