Determination of dyes in candies in an analytical chemistry laboratory subject

The use of daily life samples in laboratory subjects promotes motivation among students and therefore improves their learning. Candies are a common sample in students’ daily life, which makes their dye content an interesting analyte to determine. Food dyes are usually found in candies to increase their attractiveness by providing a bright, intense colour. Their determination is interesting due to increasing concerns in society about the use of food additives. Therefore, this learning experience aims to quantify the content of food dyes in candy samples by UV-Vis spectrometry, taking advantage of their intrinsic colour. For this determination, students need to extract the dye from the candy, take the solution to an appropriate volume and measure the absorbance. Using the external calibration curve method, students calculate the dye concentration and then use this information to compare it with the limits established by the legislation. During this practical, students have optimized the experimental procedure, solving the different problems that appeared. Also, several points were detected as good learning opportunities to discuss important aspects of the analytical chemistry. From this practical, students learn about the UV-Vis spectrometry technique, improve their practical skills of laboratory working and enhance their critical reasoning and information searching skills. In this way, students are able to contextualize the analysis performed by understanding the importance of a concentration value obtained to solve a real problem. This makes the acquired knowledge significant, profound and constructive.