Green Analytical Chemistry in Undergraduate Laboratories: Flow-Injection Determination of Creatinine in Urine with Photochemical Treatment of Waste

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 9 Issue 4 (2004) pp 242-246

Green Analytical Chemistry in Undergraduate Laboratories: Flow-Injection Determination of Creatinine in Urine with Photochemical Treatment of Waste

Paulo R. M. Correia, Rita C. Siloto, Andrea Cavicchioli, Pedro V. Oliveira, and Fábio R. P. Rocha*

Instituto de Química, Universidade de São Paulo, 05513-970, PO Box 26077, São Paulo, SP, Brazil, frprocha@iq.usp.br
Received April 1, 2004. Accepted May 5, 2004

Published online: 7 July 2004

Abstract. The introduction of green chemistry to undergraduate students is highly desirable. In the context of analytical chemistry, special emphasis should be placed on the assessment of the environmental impact of new methods in addition to traditional goals such as accuracy, precision, sensitivity, and detection limits. In particular, the amount and type of reagents consumed and wastes generated ought to be taken into account. The present work describes an experiment devised to introduce green analytical chemistry to undergraduate students. It comprises a flow-injection spectrophotometric method for the determination of creatinine in which reagent consumption is reduced by 60% compared to the corresponding batch procedure. Creatinine is determined in real or synthetic urine samples after reacting with picrate in alkaline medium and forming a red-orange product that can be quantified by UV–vis spectrophotometry. Subsequently, the wastes are photochemically degraded by UV radiation for 18 min after the addition of TiO₂ and H₂O₂. A >95% reduction of the spectrophotometric signal for picrate, measured at 354 nm, was observed. The experiment, which can be carried out in two coupled four-hour laboratory classes, highlights two key requisites of an ideal green analytical method: minimization of reagent consumption and waste management.

Key Words: Laboratories and Demonstrations; analytical chemistry; green chemistry; instrumental methods; flow-injection analysis; UV–vis spectrophotometry

(*) Corresponding author. (E-mail: frprocha@iq.usp.br)

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