LC-MS: Towards excellence in food safety


The year 2012 was marked by two major incidents in the food industry – Ireland’s horse meat scandal and Fonterra’s whey protein concentrate contamination. In January ’12, Food Safety Authority of Ireland revealed the results of a targeted study that found undeclared horse DNA in frozen beef burgers on sale in leading hypermarkets. The probe later revealed many leading names in meat processing industry in Ireland and United Kingdom, which led to tremendous embroil in both the countries.

On the other side of the world, the world’s largest dairy firm Fonterra discovered in August ’12 that some shipments of its whey protein concentrate may have been contaminated with botulism-causing bacteria. The ingredient, which was allegedly used in sports drink, animal feed and even in infant formula and shipped to nine countries across the world, led to import restriction, stepping down of senior management and huge loss to the credibility of the company.

The first incident was a case of adulteration while the other incident was contamination. However, both could be identified and traced back to the origin, thanks to state-of-the-art analytical technology. Analytical technology which mainly consists of chromatography and spectrometry technologies used in combination has proved a bliss for food manufacturers as well as consumers.

Liquid Chromatography (LC) combined with Mass Spectrometry (MS) is one of the most sensitive and selective analytical methodologies, which is widely used in food analysis. LC-MS is a rapidly growing segment which has advanced from HPLC-MS, UHPLC-MS to DART. Merck Millipore, Perkin Elmer, Phenomenex, Shimadzu, Thermo Fisher, AB Sciex, Waters and Agilent are global leaders contributing to development of LC-MS for more effective food analysis.

Advantage of LC-MS
Food may contain varieties of toxic residues and the number is increasing as a consequence of industrial development, new agricultural practices, environmental pollution and climate change. In some cases, food itself contains amount of mycotoxins – secondary metabolites of fungi that readily colonise crops or food during storage. There are several hundred pesticides – approved and banned – which are currently in use. Such harmful residues need to be screened and if found, accurately measured.

“When we receive a sample, we have to test it for presence of more than 300 pesticides. Also there may be a contaminant or residue present which has not known yet or has not been recognised yet. Testing a sample for such a high number of residues is a challenging and time-consuming task. However, with help of multi residue technique based on LC-MS, all these tests can be done on one sample,” says Dr Priti Amritkar, Director, Envirocare Labs.

Challenges ahead

“Challenges in food testing today is due to surge in development of new formulations. These new formulations have multiple nutrients, vitamins and mineral, many of them at trace levels. The challenge is to analyse each nutrient in the presence of the other,” says Dr Deepa Bhajekar, Managing Director, Microchem Silliker Lab.

Food industry is dynamic in nature with new products, process and packaging material being introduced into market constantly. Introduction of new substances, packaging material and processes can give a rise to previously unknown contaminants. Detecting non targeted compounds and determine their identity in food is a critical issue.

Development of analytical techniques is expected to play a crucial role in this. Food may contain permitted additives like enzymes and flavours. Additives differ in their structures – some have small chemical structure, some are synthetic products, some are natural extracts. This makes it difficult to choose ‘the one’ analytical method for their analysis.

Globalisation of world’s food supply has increased risks of widespread food contamination. Thus, food traceability is becoming increasingly a matter of concern in order to fight food contamination and adulteration events. It has underlined need to develop analytical techniques which can detect known as well as unknown contaminants.

Evolving for better analysis
Since its first mention in research publication in late 1970s, LC-MS methodologies have evolved to address challenges posed by needs of the food industry. Need to identify and quantify trace components have led to development of high performance and ultra high performance versions LC-MS, whereas need to deliver within short time window has led to emergence of direct analysis in real time.

High Performance Liquid Chromatography (HPLC) combined with MS is a general technique which is used to characterise various food components. HPLC-MS is a powerful tool to analyse lipid and carbohydrates content in food. In past, Gas Chromatography (GC) – MS was in use for analysis of lipids which required complex sample preparation. To simplify sample preparation, HPLC-MS has gained ground in recent years. HPLC-MS can rapidly identify unknown carbohydrates and analyse large as well as small oligosaccharides.

Flavonoids, a subgroup of polyphenols of potential healthy properties, are usually present in low amounts in plant extracts, making it difficult to isolate in higher quantities. HPLC-MS is often a method of choice in the analysis of flavonoids and food additives, given HPLC-MS’s characteristic to increase selectivity and structural information.

HPLC-MS is a useful technique in analysis and quantification of various vitamins present in traces. In recent years, HPLC-MS is superseded by Ultra HPLC-MS (UHPLC-MS), which provides better chromatographic resolution. Carotenoids, a nutrient group that gives vegetables its colour, is also analysed by UHPLC-MS due to large structural variants found in the carotenoids.

Food products may contain toxic compounds like mycotoxins, which readily colonise crops or food during storage and are often present in cereals and oilseeds. These compounds are toxic even in very small amount. Combination of HPLC with MS/MS has proved to be a powerful tool for determining various classes for mycotoxins simultaneously. It is also proven effective in analysing pesticides and allergens present in food.

Direct Analysis in Real Time (DART) is a new technique undergoing rapid developments. DART-MS technique is emerging as a tool not only for food quality and safety control but also for food authentication. An important benefit of DART is that a product can be analysed directly on surfaces like glass without having to prepare a sample. Traditional ion source used in mass spectrometry require introduction of samples in high vacuum system. DART uses atmospheric ion sources which have broadened the range of compounds that can be analysed by MS.

Towards the next best
When food is analysed it may need, not single but many, analytical approaches in order to get best-possible analysis. If the food is analysed for safety, it needs to be analysed for a range of chemicals used in agriculture. Animal products need to be analysed for presence of veterinary drugs, residues of which may appear in animal products such as eggs, poultry, fish, etc. While assessing food quality, its nutritional composition needs to be analysed for amount of lipids, carbohydrates, proteins as well as for vitamins and minerals.

Chromatographic techniques with their highly-efficient separation ability, combined with mass spectrometry, with its superior capacity of identifying different molecules present in food, is an answer to majority of analytical issues. Food is a vast subject area with a large variability due to which there is no analytical technique yet developed which can cover all aspects of food analysis. However, with ongoing technological developments in LC-MS, we may expect a comprehensive solution for food analysis in the near future.

Top companies in LC-MS:

Merck Millipore
Perkin Elmer
AB Sciex
Thermo Fisher

What’s next

Merck Millipore’s TLC-MS
Pioneer in Thin-Layer Chromatography (TLC) and in introducing the first pre-coated plates for planar chromatography applications, has now introduced the first glass plates for coupling planar chromatography with mass spectrometry. Coupling TLC plates with mass spectrometry has an advantage – flexibility in choosing mobile phases for separation, compared to HPLC-MS coupling, where certain mobile phases cannot be used. TLC-MS is a new field of high interest, which is expected to contribute substantially to the progress of planar chromatography.

Perkin Elmer’s DSA-TOF/MS
Perkin Elmer’s AxION platform has introduced DSA-TOF/MS, combining chromatographic limits of detection with Direct Sample Analysis (DSA). DSA-TOF/MS requires no or minimal sample preparation and delivers quick result. The technology can be used for food safety and regulations, food quality and consistency through the detection and analysis, food fraud detection, food lab productivity, dairy and dairy derivatives analysis and screening as well as new product development for the food consumer.

Phenomenex and AB Sciex’ sensitive assays for residue detection
Phenomenex and AB Sciex have collaborated extensively in this area to develop the most sensitive of assays with incredibly low limits of detection to detect even trace amounts of residual pesticides or other harmful chemicals utilised throughout the growing, collecting and processing of your various products, says Nick Mitchell, Managing Director, Phenomenex India.

Nikita Apraj

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