Milk and dairy products play an important role in the human diet. From infants to adults, various types of dairy products accompany us in our everyday lives and provide us with important major and trace elements, vitamins, and other essential substances. Since many dairy products are perishable and have a limited shelf life, powdered milk is the alternative for preparing milk for direct consumption or for processing into other products. The growing use of powdered milk in infant nutrition requires a strict quality control to ensure the quality of the product on a permanent basis. Here, the samples are not only examined for toxic elements such as Cd, As, Hg, and Pb but also monitored for the levels of major and trace elements. Since the elements are present in very different concentration levels ranging from g/kg to µg/kg, different analytical techniques are usually used to cover all concentration ranges.
The species or chemical form of elements determines their mobility, bioavailability and toxicity. Liquid chromatography or ion chromatography allow a separation of these species. The subsequent detection by mass spectrometry provides a highly sensitive method for their quantification. Hence, LC-ICP-MS and IC-ICP-MS provide an essential tool for assessing benefits and/or risks of elements present in the sample. An element can be essential and toxic just based on the oxidation state or compound in which it occurs. Thus, food samples like seafish, rice or chocolate, apple juice and other foods and beverages are controlled by LC-ICP-MS for arsenic, selenium or chromium species present
Next to drinking water, rice consumption is a major source of arsenic that concerns approximately 3 billion people. Studies show that arsenic exposure is more critical in rice than in any other food stuff. For example, the arsenic level in rice is 10 times higher than in wheat and barley. In addition to direct ingestion, using rice straw for cattle feed increases the risk of arsenic exposure. The toxicity of arsenic depends not only on the total concentration, but also its chemical forms as these differ in terms of mobility, toxicity and bioavailability.