Detection of Method Effects on Quality of Analytical Data. A Statistical Exercise

Systematic errors are unfortunately common in analyses performed by students in teaching laboratories. Quality control (QC) tools are required to detect and solve bias in laboratory analyses.However, although QC has become routine in real-world laboratories, it is still rarely applied in 10 teaching laboratories. For this reason, systematic errors in students' results remain unknown in many cases. In this study, the use of control charts and critical thinking methodologies are applied in laboratory lessons to show students how the control charts can be used to detect and correct systematic biases in analyses. Students practice how to evaluate out-of-control results by applying scientific critical thinking procedures based on knowledge acquired in previous subjects, aiming to 15 find the source of the bias detected, solve it, and apply rectifying measures to improve the operational procedure. With the proposed methodology, students understand the importance of control charts in demonstrating the quality and validity of the data obtained. During the academic years applying this methodology, the most common source of bias was found to be related to an incorrect application of basic laboratory skills, which shows that these skills need to be learned and, most importantly, put 20 into practice over the whole period of student training and cannot be taken for granted once they have been taught in the early stages of their curricula. The learning outcomes were assessed through an exercise that requires students to evaluate results obtained in the laboratory in previous years. It was found that the majority of students (97.6%) were able to detect a bias, find the source, and solve the error.

Section: Control Charts In Laboratory Lessonsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Use of Control Charts and Scientific Critical Thinking in Experimental Laboratory Courses: How They Help Students to Detect and Solve Systematic Errors

Sánchez

2021

“…It has been long recognized that linear calibration is not as simple as anticipated when uncertainties are taken into consideration (2)(3)(4). Thus, to estimate uncertainties on measurements, more delicate tools of statistics are required (7)(8)(9). Thus, to estimate uncertainties on measurements, more delicate tools of statistics are required (7)(8)(9).…”

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confidence: 99%

“…There are several schools of quality assurance (3)(4)(5)(6)(7)(10)(11)(12)(13) and each has its own advantages and drawbacks. There are several schools of quality assurance (3)(4)(5)(6)(7)(10)(11)(12)(13) and each has its own advantages and drawbacks.…”

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confidence: 99%

Exercise in Quality Assurance: A Laboratory Exercise

Andersen

2009

An Inquiry-Based In-Person or Remote Laboratory Using Iron Analysis and Paper Microfluidics to Teach Analytical Method Development

Frederick

Harper-Leatherman

2022

The process of method development is at the heart of analytical chemistry, yet direct experimental experience with the process is rarely taught in the undergraduate laboratory. We report here an experiment that uses rapid, safe, and inexpensive paper-based microfluidics with cell phone detection in order to facilitate the development of a colorimetric method for the determination of iron with three different derivatizing agents (thiocyanate, 1,10 phenanthroline, or FerroZine). This lab has been developed with an inquiry-based pedagogy where students determine which figures of merit to measure, the order to measure them in, and their own procedures for measuring them. This experiment gives students the opportunity to measure linear range, sensitivity, selectivity, accuracy, precision, limit of detection, and optimal reaction time for each derivatizing agent. Students then compare and contrast the measured figures of merit to make an evaluation of which method is preferred for iron quantitation. The results are variable enough from group to group, and each derivatizing agent has different advantages and disadvantages so that there is no "right" answer. This experiment is very flexible and can be modified to fit into one or two lab periods, be delivered with students working in groups or individually, and be delivered in person or in a remote setting. Student learning was assessed using the Enhancing Learning by Improving Process Skills in STEM (ELIPSS) rubrics for management, critical thinking, and information processing. Students demonstrated growth in many skills and expressed significant appreciation for their own learning.