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  Home > JCE Print > Journal of Chemical Education > Issues > 2009  > June  >
In the Laboratory
Exercise in Quality Assurance: A Laboratory Exercise
Jens E. T. Andersen
Department of Chemistry, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
Cover
June 2009
Vol. 86 No. 6
p. 733

Abstract
A laboratory exercise in quality assurance (QA) of analytical chemistry is presented. Quality assurance is considered by students to be difficult, and it is also a demanding subject to the teachers, owing to the multitude of methods available to the statisticians. In this exercise, it was demonstrated that QA could be accomplished in a straightforward manner if a few guidelines of elementary statistics were followed. The concentration of iron(III) in a iron–thiocyanate complex was measured by spectrophotometry. The method was chosen as a suitable example that was applicable to both batch experiments and to flow injection analysis (FIA). The purpose of the exercise is to compare the performance of the two independent methods of analysis by QA. By applying the law of propagation of errors and a lower limit of analysis to the analysis of variance, a satisfactory agreement was obtained between results of batch experiments and those of FIA. However, the batch experiments exhibited superior performance as compared to the performance of the FIA method with respect to sensitivity, limit of detection, lower limit of analysis, and to precision.
Supplement
Student handouts; Instructor notes
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Contents
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Citation
Andersen, Jens E. T. J. Chem. Educ. 2009, 86, 733.
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Keywords
Analytical Chemistry; Applications of Chemistry; Calibration; Hands-On Learning / Manipulatives; Instrumental Methods; Laboratory Instruction; Quantitative Analysis; Upper-Division Undergraduate; UV-Vis Spectroscopy
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History
Created:
Last Updated:
4/20/2009
5/1/2009
 Caution! 
Experiments, laboratory exercises, lecture demonstrations, and other descriptions of the use of chemicals, apparatus, instruments, computers, and computer interfaces are presented in the Journal of Chemical Education as illustrative of new or improved ideas or concepts in chemistry instruction and are directed at qualified teachers. Although every effort is made to assure and encourage safe practices and safe use of chemicals, the Journal of Chemical Education cannot assume responsibility for uses made of its published materials. Many chemicals are hazardous. Precautions for the safe use of hazardous chemicals and directions for their proper disposal are described in the Material Safety Data Sheets and on the labels. We strongly urge all those planning to use materials from our pages to make choices and to develop procedures for laboratory and classroom safety in accordance with local needs and situations.
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