Using Control Charts Early in the Quantitative Analysis Laboratory Curriculum

Abstract

Statistical process control (SPC) is used in the chemical industry to monitor manufacturing and laboratory processes to ensure quality and compliance with regulatory requirements. Control charts are a key tool used in this monitoring. Industrial job postings desire experience with SPC. Most undergraduates entering the workforce have no exposure, let alone experience, with control charts. The few available literature examples of control charts in undergraduate chemistry education involve methods of instrumental analysis at the junior or senior level of an academic program. Educators may improve the student’s preparation for working in industrial and regulatory environments by incorporating components of SPC early in the curriculum. This work provides an example of how to introduce the concept and use of control charts earlier as part of the Quantitative Analysis Laboratory curriculum. The titration of vinegar to determine the weight percent of acetic acid, using the same sample for all students, serves as a platform for this introduction. Using a provided control chart generated from historical student data, students stated in a written laboratory report if their results were within control. The scored laboratory reports and questions on the written final exam assessed student learning and retention of how to use a control chart. Meeting the learning outcomes for the laboratory exercise required the student to report the correct weight percent of vinegar and state whether their result is within control. The learning outcomes on the written final exam were met when the student answered the questions correctly, stating the given result was out of control and suggesting correct experimental changes. The goal was to see 70% or more students meet the learning outcomes. Assessment showed that a simple titration experiment enables the introduction of how to use control charts during the Quantitative Analysis Laboratory curriculum.

Blood lead levels in children residing in a 115-year old urban settlement in Harare, Zimbabwe: a cross sectional study

“…The analytical sensitivity of the assay was 1 µg/dL. In all cases, the principles of good clinical laboratory practice were observed [18]…”

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

“…The development of these skills by undergraduates is important as familiarity with process control is nowadays one of the most valuable skills required of newly hired employees in industry. 15,16…”

“…The most common use of control charts in laboratory lessons has been to assess the trueness of student results and to identify systematic errors through the monitoring of control samples. ,,− ,− When an out-of-control measurement is detected, this result and the procedure by which it was obtained should be assessed in order to detect the source of the bias and to correct either the result or the procedure to avoid further bias. However, it is not common to allow students to work by themselves in this part since the methodology to study and solve these problems differs for each specific situation, requiring the application of scientific critical thinking skills and long periods of time to find an adequate solution.…”

“…Moreover, common time-tabling restrictions on laboratory lessons usually do not allow enough time to work on these skills. In some recent studies, a critical thinking approach has been incorporated to laboratory experiments to assess method effects on the results obtained by students. ,,, These procedures are not only based on the simple visual inspection of control charts but also on the application of other critical requirements, such as knowledge of the process and a common-sense approach to analysis, on the part of students in order to reach proper conclusions and to obtain results that are within control . It has been found that the identification and discussion of real laboratory error sources by students themselves tends to be more educationally useful than putting in place the measures to eliminate these errors …”

“…The aim of this study is to demonstrate how the use of control charts can help students to develop thinking skills in laboratory lessons and to show them the importance of these methodologies in the assessment of laboratory results and to be able to optimize laboratory procedures and solve problems. The development of these skills by undergraduates is important as familiarity with process control is nowadays one of the most valuable skills required of newly hired employees in industry. , …”