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ERIC Number: EJ1090618
Record Type: Journal
Publication Date: 2016-Feb
Pages: 4
Abstractor: As Provided
ISSN: ISSN-0021-9584
Molecular Recognition: Detection of Colorless Compounds Based on Color Change
Khalafi, Lida; Kashani, Samira; Karimi, Javad
Journal of Chemical Education, v93 n2 p376-379 Feb 2016
A laboratory experiment is described in which students measure the amount of cetirizine in allergy-treatment tablets based on molecular recognition. The basis of recognition is competition of cetirizine with phenolphthalein to form an inclusion complex with ß-cyclodextrin. Phenolphthalein is pinkish under basic condition, whereas it's complex form with ß-cyclodextrin is colorless. Addition of the cetirizine leads to release of phenolphthalein from the phenolphthalein-ß-cyclodextrin inclusion complex that alters the solution color under basic conditions. The intensity of the color change is proportional to the cetirizine concentration. This simple experiment provides an opportunity for students to become familiar with the concepts of inclusion complexes and molecular recognition. Students also gain hands-on experience with a spectrophotometer and engage in plotting a calibration curve based on absorbance or color changes and determination of cetirizine.
Division of Chemical Education, Inc and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education; Postsecondary Education
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Grant or Contract Numbers: N/A