Determination of Calcium in Cereal with Flame Atomic Absorption Spectroscopy. An Experiment for a Quantitative Methods of Analysis Course

Abstract

This article describes the determination of calcium in cereal with flame atomic absorption spectroscopy. A cereal sample is crushed then dry-ashed at 600 °C in a silica crucible. The residue is treated with 5 mL of 6 M hydrochloric acid, diluted to volume, and aliquots taken and prepared for analysis using the two increment standard addition approach. The prepared solutions are aspirated into a nitrous oxide–acetylene flame and the absorbance measurements are made using the resonance line of calcium at λ = 422.7 nm, 0.5-nm slit width, and 5.0-mA lamp current. This experiment has been successfully used in the Quantitative Methods of Analysis course. It minimizes hazardous waste by eliminating the need for sample digestion with concentrated nitric acid. The results obtained by 36 students majoring in biochemistry, biology, chemistry, Earth science, or environmental science are presented. The results for the determination of calcium in two brands of cereal showed good precision with the majority (72%) of the...