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Scientific Paper

The Determination of Toxic, Essential, and Nutritional Elements in Food Matrices Using an ICP-MS

Reference Type:Journal Article
Author:Bosnak, Cynthia;Pruszkowski, Ewa
Title:The Determination of Toxic, Essential, and Nutritional Elements in Food Matrices Using an ICP-MS
Secondary Title:american laboratory
Periodical Title:american laboratory
Publishing Date: 09.05.2011
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The elemental and dynamic range of inductively coupled plasma mass spectrometry (ICP-MS) makes it ideally suited for the analysis of food materials. The ultratrace detection limits of ICP-MS permit the determination of low-level contaminants such as Pb, As, Se, and Hg, while the macro-level nutritional elements such as Ca, Mg, K, and Na can be quantified using the extended dynamic range capability of ICP-MS, which provides nine orders of magnitude. However, there are still a number of challenges to overcome, which makes the routine analysis of foods difficult unless the sample dissolution procedure is well thought out and instrumental conditions are optimized for complex sample matrices.For example, the wide variety of edible products available means that a highly diverse range of matrices must be brought into solution for ICP-MS analysis. These complex acid-digested matrices, which are a combination of dissolved carbohydrates, fats, and proteins, can pose major problems for any ICP-MS because of the potential for blocking of the interface cones and/or deposition on the quadrupole ion deflector (QID). For this reason, if instrument design does not account for high-matrix samples, long-term stability can be severely compromised.In addition to signal drift, digested food matrices can also cause major spectral complications. The sample’s organic components, together with macro minerals, can combine with elements present in the digestion acid and/or the plasma argon to form polyatomic interferences. For example, chloride ions (at mass 35) combine with the major argon isotope (mass 40) to produce the argon chloride interference 40Ar35Cl+, which interferes with arsenic at mass 75. Another example is the argon dimer (ArAr+), which forms from the plasma gas and exists at the same masses as the major selenium isotopes. In addition, the major isotope of chromium at mass 52 is overlapped by 40Ar12C, 35Cl17O+, and 35CL16OH+ interferences generated by the sample matrix and the plasma gas. As a result, these kinds of spectral interferences have made the determination of both trace and macro elements in food samples extremely challenging.To overcome these issues, a NexION® 300X ICP-MS (PerkinElmer, Inc., Shelton, CT) was used for the analysis of various food substances, focusing on toxic and typical essential and macro elements in a group of NIST® (Gaithersburg, MD) standard reference materials (SRMs).