Submitted to: Encyclopedia of Analytical Chemistry
Publication Type: Book / Chapter
Publication Acceptance Date: December 31, 1999
Publication Date: June 30, 2000
Citation: Baker, S.A., Miller-Ihli, N.J. 2000. Atomic spectroscopy in food analysis. Encyclopedia of Analytical Chemistry. 3888-3912. Interpretive Summary: This contribution is an overview of atomic spectroscopic methods for the determination of trace elements in foods and biological materials. Methods highlighted include: flame and graphite furnace atomic absorption spectrometry (FAAS and GFAAS), induc- tively coupled plasma atomic emission spectrometry (ICP-AES), and more recently, inductively coupled plasma mass spectrometry (ICP- MS). Sample preparation procedures as well as instrumental operating conditions used in the Food Composition Laboratory were used in the chapter to demonstrate the unique capabilities of each of the various techniques. Elements typically measured by FAAS using an air-acetylene flame include: Ca, Cu, Fe, Mg, Mn and Zn. ICP-AES is a multielement technique, facilitating the simultaneous determination of Ca, Co, Cu, Cr, Fe, Mg, Mn, Ni, P, V and Zn at ppb levels. GFAAS is a single element method requir- ing element specific operating conditions and the use of micro samples. ICP-MS, with solution nebulization, offers multielement detection capability, but far fewer methods exist for the analysis of the complex matrices provided by foods and biological samples. This information on analytical methods is of interest to analysts responsible for the generation of food composition data and the analysis of biological materials.
Technical Abstract: Since food is the primary source of essential elements for humans, the accurate and precise analysis of food materials is critical. The methods best suited to meet this task are: atomic absorption, atomic emission, and elemental mass spectrometry. Methods commonly used in the generation of food composition data include flame and graphite furnace atomic absorption spectrometry (FAAS and GFAAS), inductively coupled plasma atomic emission spectrometry (ICP-AES), and more recently, inductively coupled plasma mass spectrometry (ICP-MS). Flame AAS and ICP-AES offer similar detection limits (ng/mL levels); whereas, GFAAS and ICP- MS can provide sub-ng/mL detection capability. Choice of a method often depends on detection capability, but ease of use, speed of analysis, and cost must also be considered. ICP-AES and ICP-MS offer the advantage of providing simultaneous multielement measurements, making them well suited for the analysis of large numbers of elements in food samples. The most critical stage in the development of analytical methods is sample preparation. Samples can be prepared using numerous procedures, but the most useful for a wide range of analytes and sample matrices are based on dry ashing or wet ashing of the sample.