Aqueous biphasic systems (ABS) composed of polypropylene glycol and carbohydrates, two benign substances are proposed to separate two food colorants (E122 and E133). ABS are promising extractive platforms, particularly for biomolecules, due to their aqueous and mild nature (pH and temperature), reduced environmental impact and processing costs.…

In light of COVID-19 in spring 2020, we developed a simple and versatile inquiry-based, laboratory-style active learning colorimetry experiment amenable to at-home quantitative analysis. In this experiment, students acquire an external calibration method using aqueous solutions of a self-selected chromophoric analyte from household products using…

Herein, we describe an accessible and safe organic chemistry lab experiment that can be completed at home. Liquid-liquid extraction is a fundamental organic chemistry lab experiment that touches on topics such as chemical structure, density, solubility, and acid-base chemistry. Given the increased demand for safe organic chemistry experiments that…

Purpurogallin (PPG), an orange-red crystalline compound from nutgalls and oak bark, is an exemplar of numerous, ubiquitous natural colorants, biosynthesized through oxidative dimerization-decarboxylation of phenolic compounds. It possesses antioxidant, anticancer, and anti-inflammatory effects. Herein, a robust method is presented to allow…

Candy, an everyday treat, is a convenient theme for teaching chemistry. Making candy incorporates solution concentration, colligative properties, and phase transformations while flavoring and color reflect synthesis or extraction. In this article, a nonscience major laboratory course on candy chemistry is presented. The course combines laboratory…

Thin-layer chromatography (TLC) is one of the basic analytical procedures in chemistry and allows the demonstration of various chemical principles in an educational setting. An often-overlooked aspect of TLC is the capability to quantify isolated target compounds in an unknown sample. Here, we present a suitable route to implement quantitative…

Surface-enhanced Raman scattering (SERS) studies of art represent an attractive way to introduce undergraduate students to concepts in nanoscience, vibrational spectroscopy, and instrumental analysis. Here, we present an undergraduate analytical or physical chemistry laboratory wherein a combination of normal Raman and SERS spectroscopy is used to…

The combined lab and lecture course is designed around the themes of colorants (dyestuffs and pigments) and fibers (natural and human-made) for nonscience majors. Students dye natural and synthetic fibers with natural dyes such as turmeric, raspberries, tea, and cochineal insects as well as synthetic dyes. The students observe the colorfast…

A chemical separation experiment can be an interesting addition to an introductory analytical chemistry laboratory course. We have developed an experiment to extract FD&C Red Dye #40 from beverages containing cranberry juice. After extraction, the dye is quantified using colorimetry. The experiment gives students hands-on experience in using solid…

The food industry uses different additives to give foods and beverages the appearance expected by the consumer. Among them, pigments of natural origin are receiving increasing attention due to safety concerns about traditional colorants and the relevance of a healthy diet. This experiment describes the quantitative determination of the…

Oregon State Univ. has offered FST 102 "Maraschino Cherry" as a 1-credit orientation course since 1994. The maraschino cherry serves as a vehicle from which faculty give their disciplinary perspective, for example, the chemistry of the maraschino cherry, processing unit operations, microbiology and food safety, food law, sensory…

A new family of removable colored coatings that could make temporary messages is developed by employing alginates. The nontoxic, biodegradable coating is made by using calcium alginate and dyes that are widely used as food colorants and adheres easily and firmly to surfaces and could be removed by treating with a non-toxic solution of ethylene…

Dyes aren't just for fabrics--colorants have been added to food for centuries to enhance its appearance. This monograph and teaching guide investigates both the compounds that give foods their natural color and synthetic colorants currently approved for use in foods. Problem-solving inquiry based activities involve high school level students in…

Presents questions and answers regarding definitions for and differences between paints, pigments, and dyes; unique properties of diazo dyes; the differences in colorants of water base and oil base paints; and permanance of ink. (CS)

Processing of the three major groups of modern glasses is described. Low-melting-point glasses and the roles of their ingredients are discussed. Other processes (calcining, melting, fining the batch, annealing, testing for stress, colorants) are explained. Finally, a secondary-level pilot program for glass technology is suggested. (CT)