Foods, trace metal analysis

Fig. 4.12 Schematic diagram of the system for automatic sample preparation of foods for trace metal analysis.

Trace metals present in foods can have nutritional or toxicological significance and in the case of certain metals, e.g., copper and zinc, both of these. Fruit products are routinely tested for trace metal contents, e.g., canned fruits for tin, iron, copper, and zinc fruit juices for copper, zinc, and lead tomato puree for copper and also lead, tin, and arsenic. Statutory limits exist for many metals, e.g., lead, arsenic, zinc, and copper. Atomic emission spectrometry is now widely used for trace metal analysis as multielement determinations can be made on a single sample however, other methodologies are... 

Miscellaneous Samples Besides environmental and clinical samples, differential pulse polarography and stripping voltammetry have been used for the analysis of trace metals in other samples, including food, steels and other alloys, gasoline, gunpowder residues, and pharmaceuticals. Voltammetry is also an important tool for... 

Analytical Procedures. Standard methods for analysis of food-grade adipic acid are described ia the Food Chemicals Codex (see Refs, ia Table 8). Classical methods are used for assay (titration), trace metals (As, heavy metals as Pb), and total ash. Water is determined by Kad-Fisher titration of a methanol solution of the acid. Determination of color ia methanol solution (APHA, Hazen equivalent, max. 10), as well as iron and other metals, are also described elsewhere (175). Other analyses frequendy are required for resia-grade acid. For example, hydrolyzable nitrogen (NH, amides, nitriles, etc) is determined by distillation of ammonia from an alkaline solution. Reducible nitrogen (nitrates and nitroorganics) may then be determined by adding DeVarda s alloy and continuing the distillation. Hydrocarbon oil contaminants may be determined by ir analysis of halocarbon extracts of alkaline solutions of the acid. 

Boyer KW, Horowitz W. 1986. Special considerations in trace element analysis of foods and biological materials. In O Neill IK, Schuller P, Fishbein L, eds. Some metals As, Be, Cd, Cr, Ni, Pb, Se, Zn. lARC Scientific Publication No. 71, Lyon, France International Agency for Research on Cancer, 191-220. 

There is still much ongoing debate on the validity of the different approaches to perform dietary analysis (single food analysis, duplicate diet analysis, total diet, and total mixed diet analysis) to provide an adequate answer to nutritional questions. The approach followed in this study has proven useful for the assessment of the actual dietary intake of trace metals that may be lost and/or added during the preparation of meals. The measurements done on cooked samples prepared according to the Italian local traditions provides an assessment of the actual concentrations of trace elements uptaken by the population through the diet. 

Probably the most popular and, as it proved to be, the most contentious use of hair analysis was its application to the evaluation of nutritional deficiencies. Many food faddists, pharmacists, nutritionists, and some physicians were convinced that a person s well being was influenced by the concentration of trace metals in his hair. The demands for hair analysis became very large. Many laboratories, some with dubious competence, were estabhshed to satisfy what seemed to be a limitless, ever growing service demand. With the passage of time, however, proponents of this... 

Stripping analysis has been widely used for measuring trace metals in biological fluids. The use of stripping analysis for decentralized testing of blood lead in children has been particularly successful [46]. Measurements of mercury in fish [48], of antimony in gunshot residues [40], or of cadmium impurities in zinc plant electrolyte [55], represent typical food, forensic, and industrial applications, respectively, of stripping analysis. These,... 

Some of the many uses for ICP-MS include analysis of environmental samples for ppb levels of trace metals and nonmetals the analysis of body fluids for el ental toxins such as lead and arsenic determination of trace elanents in geological samples, metals and alloys determination of isotope ratios analysis of ceramics and semiconductors analysis of pharmaceutical and cosmetic samples determination of platinum group catalysts in polymers forensic analysis elemental analysis in the petroleum and chemical industries and metal determinalions in clinical chemistry and food chemistry. 

The Environment - Analysis and Removal of Pollutants Trace Metal and Analysis Food and Drug Control... 

Microscopists in every technical field use the microscope to characterize, compare, and identify a wide variety of substances, eg, protozoa, bacteria, vimses, and plant and animal tissue, as well as minerals, building materials, ceramics, metals, abrasives, pigments, foods, dmgs, explosives, fibers, hairs, and even single atoms. In addition, microscopists help to solve production and process problems, control quaUty, and handle trouble-shooting problems and customer complaints. Microscopists also do basic research in instmmentation, new techniques, specimen preparation, and appHcations of microscopy. The areas of appHcation include forensic trace evidence, contamination analysis, art conservation and authentication, and asbestos control, among others. 

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