A series of undergraduate laboratory experiments that utilize reversed-phase HPLC separation, inductively coupled plasma spectroscopy (ICP), and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) are described for the analysis of commercial sunscreens. The active ingredients of many sunscreen brands include zinc or titanium oxide in addition to organic acids. Students determine the zinc content using ICP, and the chemical composition as well as particle sizes using SEM-EDS. The organic UV absorbers octocrylene and oxybenzone are quantified using HPLC. With the incorporation of these interesting characterization techniques in second or fourth-year chemistry courses, and by having students analyze sunscreen samples that are medically relevant in terms of health effects, students engage in timely research and at the same time gain exposure to a variety of instruments in the analysis of a familiar household product.
The chemistry department at Washington & Jefferson College implemented an "organic first" curriculum in the fall semester of 2005. Assessment data suggest that the net impact of this change for the department and associated constituencies has been positive: (i) Student outcomes have generally not been impacted by the curricular change, though a significant improvement in student performance on a standardized analytical exam has been observed. (ii) The department has attracted more majors, and can use faculty resources differently as a two-semester general chemistry sequence is no longer offered. (iii) The biology program reports greater student success in introductory biology, in part because of the organic chemistry background students now acquire earlier.
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 experiments and candymaking exercises, illustrating general chemistry principles and data collection. For example, students investigate crystal formation with rock candy and fudge, browning reactions with UV−vis spectroscopy and caramels, enzyme kinetics with polarimetry and cherry cordials, and freezing point depression with temperature measurements and ice cream. Imitation and natural flavors are obtained through Fischer esterification and distillation, respectively, while colorants are characterized through chromatography and spectroscopy. The course incorporates statistics through sensory analysis and color distribution. Student assessment and feedback as well as a poster/tasting session are also described.
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