A Caffeinated Boost on UV Spectrophotometry: A Lab for High School Chemistry or an Introductory University Chemistry Course

Abstract

This laboratory experiment challenges students to identify the country of origin of raw coffee beans from around the world by calculating the percent caffeine and percent water in the supplied samples. The implementation of this experiment enables students in introductory chemistry classes to gain greater understanding of the chemical analysis process and the Beer−Lambert law. Using commercially available raw (green) coffee samples, students extract caffeine from the grounds as an aqueous solution and determine the percent caffeine using UV− vis spectrophotometry. In a second portion of the experiment, raw beans are roasted to determine the percent water content. Using both pieces of data, students are asked to identify the country of origin of given coffee samples in which the percent caffeine ranged from 1.14 to 1.80% (w/w) and the percent water loss ranged from 3.27 to 10.8% (w/w).

Separation of Caffeine from Beverages and Analysis Using Thin-Layer Chromatography and Gas Chromatography–Mass Spectrometry

“…Its use in the general chemistry laboratory curriculum has become more common in recent years, demonstrating the suitability of incorporating such instrumentation into an introductory course. − This experiment has been conducted with over 3500 on-campus and dual credit General Chemistry I students at MWSU. The detection of caffeine in beverages using high-performance liquid chromatography (HPLC), including coffee, , soft drinks, and energy drinks; nuclear magnetic resonance (NMR) of energy drinks; and UV–visible spectrophotometry (UV–vis) of coffee extracts has been reported for use in the instructional laboratory. Only two of these experiments , are targeted for the general chemistry laboratory.…”

“…The detection of caffeine in beverages using high-performance liquid chromatography (HPLC), including coffee, , soft drinks, and energy drinks; nuclear magnetic resonance (NMR) of energy drinks; and UV–visible spectrophotometry (UV–vis) of coffee extracts has been reported for use in the instructional laboratory. Only two of these experiments , are targeted for the general chemistry laboratory. The ultimate goal of the “CAP 2” experiment is to successfully identify caffeine in the extract while potentially identifying other substances, such as those possibly added as flavoring agents, in the drink.…”

Simultaneous Determination of Pyridoxine and Riboflavin in Energy Drinks by High-Performance Liquid Chromatography with Fluorescence Detection

“…These drinks contain caffeine, taurine, riboflavin, pyridoxine, other B vitamins, and various herbal derivatives . Caffeine has been established as a target analyte in many undergraduate analytical chemistry courses, and several methods for its determination in different samples have been described. − Pyridoxine has also been determined by high-performance liquid chromatography (HPLC), using UV detection, in undergraduate analytical chemistry courses. In that case, the chromatogram exhibited relatively high noise around the pyridoxine peak and the standard addition method was used for the determination .…”

Spectrophotometric Determination of 6-Propyl-2-thiouracil in Pharmaceutical Formulations Based on Prussian Blue Complex Formation: An Undergraduate Instrumental Analysis Laboratory Experiment

“…During the experiment, students collect experimental results and calculate the amount of a drug in pharmaceutical preparations. Teachers may transform the student handouts to make this need an inquiry-based laboratory investigation suitable for students finishing a laboratory course at a high school or university general chemistry level …”