Determining the ibuprofen concentration in liquid-filled gelatin capsules to practice collecting and interpreting experimental data, and evaluating the methods and accuracy of quality testing

A laboratory experiment to determine the concentration of the anti-inflammatory drug ibuprofen in liquid gelatin capsule dosage forms, suitable for undergraduate chemistry or pharmacy students, is described. Either individually, or in small teams, the students digest two 200 mg capsules in a KOH solution. While the capsules are digesting the students prepare a range of ibuprofen standards and determine their UV absorbance at 264 nm. Next, the students use the data to both determine the drug's extinction coefficient using the Beer-Lambert equation and to plot a calibration graph. Using both the extinction coefficient and the calibration graph the students are then required to determine the amount of ibuprofen in each of their capsules. In undertaking the laboratory class, the students are required to complete a results data sheet, determine whether the capsules are within specification, and answer questions that prompt them to evaluate the different calculation methods and the accuracy of the tests. In their final exam, the students were asked three multiple choice questions and one multistep calculation question related to the laboratory class. The results of the students' final exam show that the learning objectives of the laboratory were broadly met, with students being able to demonstrate an understanding behind the science of the laboratory, and an ability to undertake simple, as well as complex, calculations.