#43 - Estimating carminic acid content in cochineals: a spectroscopy experiment based in the chemistry of art

Abstract

History shows that humans, for the longest time, have been interested in coloring their clothes. To accomplish this, they would use dyes readily available from natural sources such as minerals, plants and animals. One of the most evasive dyes was red because it was hard to obtain and would fade rather quickly. However, more vibrant and resistant red dyes could be obtained from madder root and cochineals. Cochineals are beetles that contain a strong red colorant called carminic acid, which is nowadays commercially available. This project focuses on finding the average mass of carminic acid present in cochineals using spectroscopy. In this presentation, we will use Beer's law to estimate the amount of carminic acid in the cochineals, using both a research grade UV-Vis spectrophotometer and a Vernier portable instrument commonly found in high schools, thus creating an experiment that can be used at the high school and college level.