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Atomic Absorption Spectroscopy of Calcium in Foodstuffs in Non-Science-Major Courses W
Inspired by Markow's "analysis of lead in paint chips" experiment (I), Sherren's use of real-life, familiar samples in quantitative analysis (2), and student interest in osteoporosis, a decision was made to augment our student AAS experience of analyzing lead in water to include the measurement of calcium in items "eaten" by students.
Background
Calcium, the fifth most abundant element in the human body (after C> H, N, and O), comprises up to 2.0% of our body's mass and is largely contained in our bones and tooth enamel (3). It is found in milk and dairy products, sardines, broccoli and other dark green vegetables, and legumes, and is added to vitamins and other dietary supplements (4).
In addition to being in our bones and teeth, calcium plays a key role in maintaining cell membrane integrity and in cell-to-cell adhesion; it also regulates such cell activities as release of neurotransmitters, chemotaxis, muscle contraction, exocytosis/endocytosis, blood clotting, chemiluminescence, and fertilization (S). Recent evidence also suggests a major role for calcium in battling major illnesses such as high blood pressure, colon cancer, and diabetes (6).
At least 42 articles dealing with calcium have been published in this Journal. Reported analyses of Ca using AAS have included determination of the phosphate interference in the flame analysis of calcium (7), calcium level in fruit juice (8), metal concentration in pure water by graphite furnace (9), calcium percentage in an analgesic tablet (10), calcium in serum samples through use of fuel-lean flame (11), analysis of calcium in brine (12), and optimization of signal/noise ratio using simplex optimization (13).
Experimental Procedure
In this experiment, non-science-major students are given a brief introduction to the terms ppm (parts per million) and ppb (parts per billion). They then measure out 1 mL of any food color and prepare a 1-ppm solution of this food color in water.
How this solution is prepared (and how much there is of it) and what materials are needed in its preparation are left to the discretion of each group. Little instructor input, other than confirming the final I-ppm solution, is offered during this cooperative learning exercise.
After students complete this introductory activity, a demonstration...