Overcoming Matrix Effects in a Complex Sample: Analysis of Multiple Elements in Multivitamins by Atomic Absorption Spectroscopy

Abstract

A multivitamin tablet and liquid are analyzed for the elements calcium, magnesium, iron, zinc, copper, and manganese using atomic absorption spectrometry. Linear calibration and standard addition are used for all elements except calcium, allowing for an estimate of the matrix effects encountered for this complex sample. Sample preparation using standard lab chemicals and equipment allows for this experiment to be easily incorporated into undergraduate analytical laboratory courses.

Analysis of Natural Materials’ Adsorption Efficiency Relating Co(II) Using Atomic Absorption Spectroscopy: Laboratory Experiment

“…In this way, they have an opportunity to solve research issues which are interesting and also relevant for their own lives. 1−8 A generally acceptable technique to determine metals in alimentary samples, 9−11 multivitamin tablets, 12 or daily products 13−15 is atomic absorption spectrometry (AAS), which is based on the absorption of optical radiation by free atoms.…”

“…Many publications for students contain descriptions of laboratory experiments through which the students gain practical knowledge with a variety of analytical techniques. In this way, they have an opportunity to solve research issues which are interesting and also relevant for their own lives. − A generally acceptable technique to determine metals in alimentary samples, − multivitamin tablets, or daily products − is atomic absorption spectrometry (AAS), which is based on the absorption of optical radiation by free atoms.…”

Analysis of Ethanol in Beer Using Gas Chromatography: A Side-by-Side Comparison of Calibration Methods

“…A typical approach in these courses is to introduce the common calibration methods (i.e., external standards, standard addition, internal standards) and their associated calculations in the lecture component of the course, followed by technical skill building in the laboratory where the students have an opportunity to conduct their own calibration. While there are numerous examples of laboratory activities in which students are directed to use a specific calibration technique for analysis, it is less common to find experiments where the students are required to validate an assigned method/calibration by using techniques such as spike analysis, or directly comparing different calibration techniques. − These types of evaluation and decision-making skills are critical not only within analytical chemistry coursework, but also in upper-division chemistry courses, as well as in students’ future careers. In an effort to provide such an experience, I have previously aimed to introduce students to the advantages and disadvantages of the various calibration methods using a small group active learning exercise, but this activity was not designed for the laboratory and focuses on a different analyte for each calibration method, making quantitative and statistical comparisons impossible.…”

Guided-Inquiry Experiment for Teaching the Calibration Method of Standard Addition in the Analysis of Lead with Graphite Furnace Atomic Absorption Spectroscopy

“…Numerous examples of innovative projects have been reported in the literature, yet most adhere to traditional modes of direct instruction. − In comparison with that of traditional direct instruction, guided-inquiry pedagogical approaches have demonstrated positive effects on retention of information, the development of inquiry skills, and the potential for life-long learning and student motivation. − Unfortunately, guided-inquiry lessons are not yet well-represented in analytical chemistry education literature. More common examples of traditional didactic instruction in the literature are of lessons designed where students are told when a matrix effect is present and the explicit calibration steps necessary to overcome these matrix effects via standard addition. − Analytical textbooks do a good job of discussing the advantages and disadvantages of a calibration curve (external standardization) in comparison with standard addition calibration techniques, yet students rarely face scenarios in which the choice between the two is necessary. − Students readily appreciate that external standardization provides a significant savings in time and work when analyzing samples. Students are also typically aware that matrix effects often necessitate a standard addition calibration in lieu of the more common external standardization/calibration curve approach.…”