The Chemical Educator
ISSN: 1430-4171 (electronic version)
Abstract Volume 9
Issue 4 (2004) pp 234-238
Chemometrics in the Teaching Laboratory. Quantification of a Ternary Mixture of Common Pharmaceuticals by First- and Second-Derivative IR Spectroscopy
Juan Ricardo Lucio-Gutiérrez, María de la Luz Salazar-Cavazos, and Noemí Waksman de Torres*
Department of Analytical Chemistry, Faculty of Medicine,
U.A.N.L., P.O. Box 2316, Sucursal Tecnológico, 64841 Monterrey, N.L.,
Published online: 13 July 2004
Abstract. In this article, a quantification model using infrared is presented in which derivative spectroscopy is applied to a ternary mixture of substances commonly used in undergraduate laboratories, namely, acetylsalicylic acid (ASA), salicylic acid (SA), and caffeine (C). Optimal working conditions are as follows: for SA and ASA, first derivative, second-degree polynomial, 11 smoothing points at 1145 and 1707 cm–1, respectively; for caffeine, second derivative, second-degree polynomial, 11 smoothing points at 1707 cm–1. We consider that the procedure described here is useful for the teaching of chemometrics as it presents a series of theoretical and practical considerations that must be taken into account when using a technique such as derivative spectroscopy.
Key Words: Laboratories and Demonstrations; physical chemistry; analytical chemistry; instrumental analysis; IR
(*) Corresponding author. (E-mail: email@example.com)
Supporting Materials:A quantification model using Infrared is presented, in which derivative spectroscopy is applied to a ternary mixture of substances commonly used in undergraduate laboratories, namely acetylsalicylic acid (ASA), salicylic acid (SA) and caffeine (C) is available in one Zip file. (197 KB).
Issue date: August