Qualitative and Quantitative Analysis of Spinach Extracts: A Modular, Inexpensive, and Bench-Friendly Protocol

The chromatographic separation of
plant pigments is one
of the
most popular and visually appealing experiments encountered by young
scientists when they are introduced to the principles of analytical
chemistry. As such, it has found widespread application in schools,
public engagement activities, and undergraduate laboratories. However,
most of the methods used in these contexts suffer from a range of
limitations, including the difficulty of separating and isolating
individual pigments when using paper-based or thin layer chromatography
techniques or the need for specialized spaces in order to contain
volatile, harmful solvents and dry silica powder. This new modular
laboratory protocol has been developed following green chemistry principles
and employs a series of inexpensive, bench-friendly methods. The protocol
allows for the separation and quantitation of chlorophyll pigments
in plant extracts through the use of prepacked, inexpensive reversed-phase
chromatography columns and UV-vis spectrophotometry. A synthetic component
is added to the more traditional separation experiments through the
development of the bench-friendly synthesis of coloring agent E141,
a chlorophyll-derived food dye. The protocol embeds analytical and
mathematical components that encourage students to engage in problem
solving activities and mathematical modeling early on in their studies.