A Solvent Microextraction Approach for Environmental Analysis: Colorimetric Assay for Phosphorus Determination in Natural Waters

We describe a hands-on experience designed for students in an upper-division undergraduate analytical laboratory for the UV–vis spectrophotometric determination of phosphorus in natural waters using a current microextraction technique. The method is based on the formation of a colored ion pair and its subsequent extraction in a microdrop of organic solvent. The proposed laboratory experiment allows the students to gain experience in developing a green sample preparation approach. Furthermore, the extraction of a colored product allows them to better understand different issues that govern solvent microextraction. Optimization of some experimental parameters and the chemical analysis of natural waters are also addressed in this laboratory experiment.