Determination of the Weight Percent of Dye in Marshmallow Candy Using External Standards and Standard Addition

This experiment involves determining the weight percent of FD&C Yellow #5 in a marshmallow candy sample using external standard and standard addition methods. The procedure reported herein was developed for use in an undergraduate general chemistry or quantitative analysis laboratory course to provide a hands-on approach introducing both methods. Standard addition is a method used to correct for matrix effects in a solution among other issues. If an analyte is mixed with other materials, those other materials, referred to as a matrix, have the potential to affect the analytical method’s reliability with respect to sensitivity, selectivity, linear range, etc. The experiment illustrates to students a simple matrix correction in a tangible, inexpensive way using a sample likely familiar to the experimenter, a marshmallow candy. The range of weight percent FD&C Yellow #5 determined by students was 0.0057 to 0.241 using both methods. As a result of completing the experiment, students were able to achieve an understanding of both external standard and standard addition calibration methods. Students (1) developed an understanding of Beer’s Law and its application, (2) visualized and applied the methods of standard addition and external standards, and (3) developed sample and standard solution preparation skills. Students also gained ability to generate calibration curves and analyze experimental data to ultimately compare their weight percent of dye to the acceptable daily intake of FD&C Yellow #5.