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From: Food Quality & Safety magazine, October/November 2012

Atomic Absorption for Trace Element Analysis in the Food and Beverage Industry

by Hazel Dickson, PhD

Atomic absorption, an established analytical technique that has been used worldwide for decades, offers many advantages for an extended range of applications across multiple industries. The technique is increasingly being used in the food and beverage industries to ensure compliance with stringent global legislation.

Combining flame, furnace, and vapor techniques, AA facilitates the analysis of a large number of toxic trace elements across a wide analytical range, from parts per million (ppm) down to subparts per billion (ppb). The technique can achieve the required low detection limits, and it offers maximum ease of use, sensitivity, and accuracy. These characteristics make AA an ideal choice for the analysis of trace elements in foodstuffs.

Approximately 72 trace elements are required for the proper functioning of the human body. Phosphorus is needed for muscle and tissue growth, and calcium is critical for normal cell operation. Small amounts of zinc and manganese are also required for hormone production and enzyme function. Unlike most vitamins and minerals, trace elements are needed in extremely low quantities, and deficiency or excess of these elements can have a negative impact on the overall health of the human body.

Certain trace elements are toxic, including arsenic, mercury, and lead, and their consumption has been associated with serious health problems. Exposure to harmful trace elements occurs most commonly through ingestion of food that has been contaminated during production.

Increasing public awareness places pressure on producers and suppliers of food and beverages to ensure product quality and safeguard consumer health. Toward that end, global regulatory bodies have introduced stringent legislation to control trace elements in food products.

AA is a key player in the analysis of trace elements in foodstuffs, and it is the chosen technique for laboratories requiring regular dedicated analysis. Analytical laboratories demand robust and reliable methodologies and instrumentation. AA provides excellent sensitivity, accuracy, and precision.

Regulatory Outlook

Legislation is being imposed worldwide to protect consumer health by controlling contaminants and toxins in foodstuffs. The Codex Alimentarius, established by the Food and Agriculture Organization of the United Nations and the World Health Organization in 1963, provides internationally recognized standards, guidelines, and codes of practice. The greatest number of standards and controls are aimed at arsenic, cadmium, lead, mercury, and tin. The maximum level of a toxic element in foodstuffs, which is typically set around 0.1 mg/kg, can vary depending on country or region, food type, and typical consumption.

A wide range of trace elements is also covered by regulations and guidelines on labelling and nutritional content. When a nutrient declaration is applied, foodstuffs that provide more than 5% of the nutrient reference value (recommended daily allowance) per 100 grams are usually stated. Nutritional elements include calcium, magnesium, iron, zinc, iodine, copper, and selenium. Fortified products such as iron-enriched cereals and calcium-enriched yogurts and dairy drinks must also quantify fortification claims on the label.

Sodium content is usually listed with the main nutritional information. Sodium comes not only from salt but also from many other additives and preservatives– monosodium glutamate, sodium saccharin, and sodium bicarbonate–particularly in foods requiring water reconstitution. In fact, more than 75% of the sodium consumed in a typical diet comes from manufactured and processed foods, rather than from salt added during cooking or at the dinner table.

Because food and beverage manufacturers and suppliers are required to regularly monitor the trace element concen- trations in their products, food analysis and testing laboratories need a method to perform rapid and reliable analyses.

Atomic absorption, an established analytical technique that has been used worldwide for decades, offers many advantages for an extended range of applications across multiple industries. The technique is increasingly being used in the food and beverage industries to ensure compliance with stringent global legislation.

Benefits of AA

AA is a key player in the analysis of trace elements in foodstuffs, and it is the chosen technique for laboratories requiring regular dedicated analysis. Analytical laboratories demand robust and reliable methodologies and instrumentation. AA provides excellent sensitivity, accuracy, and precision. Advances in automation through online sample dilution and automated standard preparation simplify routine tasks and offer increased productivity and sample throughput.

One of the fastest growing markets in food safety is China, mirrored by the continued growth of the Chinese gross domestic product. The Food Safety Law, passed in China in June 2009 to toughen penalties against manufacturers of mislabeled or tainted food, has significantly raised the food safety profile in this region and increased the trace elemental analysis of foodstuffs. China is the world’s largest exporter of fruit and vegetables, with meat, fish, and cereals such as rice contributing significantly to its exports.

The analysis of trace elements in food is important; some laboratories analyze more than 100 samples per day. Flame AA offers a simple, dedicated solution, and with the use of an intelligent online dilution system and autosampler, provides complete automation over several orders of magnitude. Flame and furnace systems can also be used as complementary techniques for the analysis of multiple elements in the same sample. For example, the global annual production of rice–the staple food of most Asian countries–is approximately 600 million tons. In rice, Flame AA can analyze essential elements such as manganese and zinc, while furnace AA can be used to ensure that toxic elements such as cadmium and lead are below legislative limits. A major benefit of furnace AA is the small sample volume required for analysis. Typically, only a few microliters of sample are needed, allowing minimal dilution on the original sample to achieve the best detection limits.

The unique elemental properties of mercury can make it difficult to analyze using standard flame and furnace methods. A continuous flow system with on-line mercury reduction and cold vapor generation, however, allows detection limits in the ppb range to be achieved. This is comparable to the detection limits achieved with inductively coupled plasma optical emission spectrometry, yet the fact that it is a simple and economical solution makes it accessible to laboratories worldwide. The method has been used for the analysis of mercury in fish. Minamata Bay, located in the Kumamoto Prefecture of Japan, had more than 10,000 individual cases of mercury poisoning following the disposal of mercury-contaminated wastewater into the local river. It was several years, however, before the effects were observed and the source of the contamination identified. Bioaccumulation of mercury in the marine food chain results in high levels in predatory fish such as tuna, leading to poisoning in humans.

To ensure the quality of products, protect the consumer health, and comply with safety regulations and standards, companies in the food and beverage industries must perform rigorous testing and real-time monitoring of trace elemental concentrations in their products. AA is an established, powerful, and cost-effective technique that analyzes trace elements in a simple, accurate, dependable, and rapid manner. The technique offers flame, furnace, and vapor capabilities in combination with preparative accessories and automation and provides versatile, robust, and reliable configurations for even the most challenging applications.


Hazel Dickson is atomic absorption applications specialist for Thermo Fisher Scientific, Cambridge, UK. Reach her at hazel.dickson@thermofisher.com or by phone at +44 (0) 1223 347 400.

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