Chemistry of Autumn Colors: Quantitative Spectrophotometric Analysis of Anthocyanins and Carotenoids and Qualitative Analysis of Anthocyanins by Ultra-performance Liquid Chromatography–Tandem Mass Spectrometry

Abstract

The autumnal leaf color change is a familiar phenomenon to most students living in temperate climate zones. The extraction and analysis of the pigments of the autumn leaves provide an engaging way to study the phenomenon utilizing both simple as well as more sophisticated analytical methods. In this laboratory experiment, students extract the red and yellow pigments, that is, anthocyanins and carotenoids from leaves and separate them from each other by liquid–liquid extractions. From the separated phases, anthocyanin and carotenoid concentrations can be evaluated visually or spectrophotometrically. The anthocyanins are analyzed by a rapid and simple ultra-performance liquid chromatography–tandem mass spectrometry method to discover which of the six most common groups of anthocyanins are present in the sample. The simplicity of the experiment setup allows it to be used as an introduction to mass spectrometry since the results can be easily interpreted without complicated data processing. The experiment provides opportunities for learning outside the classroom, as the samples can be collected from the nearby parks or forests and analyzed using more sophisticated methods on a student visit to a university or other research institution. The sample preparation followed by the visual analyses of the phases is however simple enough to be performed in a regular school laboratory.

Crime Scene Investigation: Simulated Post-mortem LC–MS/MS Analysis of Cocaine and Cocaine Metabolites in Synthetic Human Serum

“…Published experiments include a study of vanillin in vanilla extract, 5 amoxicillin in river water, 6 perfluorinated surfactants in fish liver, 7 drugs on paper currency, 8 xanthines in guaranáfruit powder, 9 and anthocyanins in leaves. 10 In a clinical setting, LC−MS/MS is more valuable than GC−MS or LC−MS because it has the ability to discriminate target drugs from hundreds of other substances in biological fluids such as blood serum or urine. 4 This lab experiment introduced students to a relevant LC−MS/MS application of cocaine quantitation in blood serum.…”

“…There are few published LC–MS/MS laboratory experiments for undergraduate instruction, especially laboratories with MRM. Published experiments include a study of vanillin in vanilla extract, amoxicillin in river water, perfluorinated surfactants in fish liver, drugs on paper currency, xanthines in guaraná fruit powder, and anthocyanins in leaves . In a clinical setting, LC–MS/MS is more valuable than GC–MS or LC–MS because it has the ability to discriminate target drugs from hundreds of other substances in biological fluids such as blood serum or urine .…”

Identification of Tree Species by Their Defense Compounds: A Study with Leaf Buds of White and Silver Birches

“…Analytical techniques combining liquid chromatography (LC) to mass spectrometry (MS) are routinely used in chemistry research, and numerous laboratory experiments utilizing LC-MS have been published in this Journal . − However, only a small number of them provide a context that students would be familiar with from everyday life. In order to introduce this modern technique to students, a familiar context could make the abstract theory more interesting and worth understanding .…”

“…In order to introduce this modern technique to students, a familiar context could make the abstract theory more interesting and worth understanding . Even smaller number of the experiments have been designed for an audience outside of university . Yet, they would benefit the most from having a glance into the world of chemistry research by trying out the instruments used by scientists, since students outside university do not usually have a possibility to use modern methods and instruments.…”

K-5 Thin-Layer Chromatography: Three-Dimensional Analysis of Pigments from Plant Materials Using an Interlocking Building-Block Photography Box

“…The elementary school students extract a mixture of chlorophyll, flavonoids, carotenes, and/or anthocyanins from plant materials. As previously reported, thin-layer chromatography has been used to separate plant pigments, and based on their color students can differentiate the pigments present. − …”