Undergraduate Analytical Chemistry Research Articles

Understanding, Deriving, and Computing Buffer Capacity

The concept of buffer capacity appears in varied disciplines, including bio-, geo-, analytical, and environmental chemistry, physiology, medicine, dentistry, and agriculture. Unfortunately, however, derivation and systematic calculation of buffer capacity is a topic that seems to be neglected in the undergraduate analytical chemistry curriculum. In this work, we give an account of the development of the buffer capacity concept and derive the buffer capacity contribution equations for buffer systems containing mono-, di-, and triprotic weak acids (and their conjugate bases) and aluminum(III), which undergoes hydrolysis. A brief review of pH is provided because pH is involved in applying buffer capacity to the real world. In addition, we discuss evaluation of the equations, numerical approximation of buffer capacity when an analytic solution is not derived, and the mathematical properties of the buffer capacity expressions.

Teaching Sample Preparation in the Undergraduate Laboratory

Teaching sample preparation in an undergraduate analytical chemistry laboratory provides many challenges. For example, the time required to properly digest a sample means that sample preparation and method development are often deliberately overlooked in the undergraduate laboratory. To teach sample preparation, we have developed an experiment for the acid digestion of an iron ore sample in a microwave oven. From a pedagogical perspective, the microwave oven has the advantage of allowing easy control of experimental parameters such as heating power and time. This experiment requires two 3-hour lab periods. One lab period is required for determining the optimum conditions to achieve maximum extraction of Fe from an iron ore sample. The digestion parameters used for this experiment are choice of acid, digestion time at a fixed microwave power, and microwave power at a fixed time. A second lab period is required for the preparation of calibration standards and the analysis of the ore samples for Fe using flame atomic absorption spectroscopy. Using the optimum digestion parameters, Fe was measured in a known ore sample and was within 2% of the expected concentration.

Urban air: real samples for undergraduate analytical chemistry.

Urban air: real samples for undergraduate analytical chemistry.

Probiotics Production: An Interesting Example for the Undergraduate Analytical Chemistry Laboratory

An analytical chemistry laboratory experiment for undergraduates that combines traditional analytical chemistry techniques with the interdisciplinary field of biotechnology is presented. It involves a process in which the combination of a yeast (Schizosacaromyces pombe) and a bacteria (Acetobacter xylimun), usually named Kombucha, in a very simple culture of commercial black tea and glucose produces metabolites that are sampled and quantified by students. Students determine the biomass and quantify the production of several organic acids, and the consumption of glucose. This is an interdisciplinary project where students apply many tools of the general analytical process and combine results obtained by all the participating students to learn the characteristics of a biotechnological process. Overall, the system discussed is easy to implement because the selected micro-organisms are not pathogenic, are safe and easy to manipulate, and are resistant to contamination.

Determination of Anionic Surfactants Using Atomic Absorption Spectrometry and Anodic Stripping Voltammetry

An experiment has been developed for our undergraduate analytical chemistry course that demonstrates the indirect analysis of anionic surfactants by techniques normally associated with metal ion determination; that is, atomic absorption spectroscopy (AAS) and anodic stripping voltammetry (ASV). The method involves the formation of an extractable complex between the synthetic surfactant anion and the bis(ethylenediamine)diaqua copper(II) cation. This complex is extracted into chloroform and then back-extracted into dilute acid. The resulting Cu(II) ions are determined by AAS and ASV. Students are required to determine the concentration of a pre-prepared "unknown" anionic surfactant solution and to collect and analyze a real sample of their choice. After the two extraction processes, students typically obtain close to 100% analytical recovery. Correlation between student AAS and ASV results is very good, indicating that any errors that occur probably result from their technique (dilutions, extractions, preparation of standards, etc.) rather than from the end analyses.The experiment is a valuable demonstration of the following analytical principles: indirect analysis; compleximetric analysis; liquid-liquid (solvent) extraction; back-extraction (into dilute acid); analytical recovery; and metal ion analysis using flame-AAS and ASV.

Internal Standard Calculations in Chromatography

This paper outlines a simple approach to internal standard calculations in chromatography. It enables students to cope with an important but troublesome calculation often ignored by undergraduate analytical chemistry texts.

Peer Reviewed: Cooperative Group Learning in Undergraduate Analytical Chemistry

With problem-based learning, students are more fully engaged in the learning process, and their understanding of the process of chemical analysis is increased.

Using Microwave Sample Decomposition in Undergraduate Analytical Chemistry

A shortcoming of many undergraduate classes in analytical chemistry is that students receive little exposure to sample preparation in chemical analysis. This paper reports the progress made in introducing microwave sample decomposition into several quantitative analysis experiments at Truman State University. Two experiments being performed in our current laboratory rotation include closed vessel microwave decomposition applied to the classical gravimetric determination of nickel and the determination of sodium in snack foods by flame atomic emission spectrometry. A third lab, using open-vessel microwave decomposition for the Kjeldahl nitrogen determination is now ready for student trial. Microwave decomposition reduces the time needed to complete these experiments and significantly increases the student awareness of the importance of sample preparation in quantitative chemical analyses, providing greater breadth and realism in the experiments.

Complexometric Titration of Zinc: An Analytical Chemistry Laboratory Experiment

Complexometric titrations with EDTA have traditionally been performed in undergraduate analytical chemistry courses to determine the calcium or magnesium content of water. These titrations are performed at a basic pH, where the formation constants of Ca-EDTA and Mg-EDTA complexes are high. These types of problems are well-treated in the analytical chemistry textbooks. In contrast, treatment of metal ions whose EDTA complexes occur significantly at low pH (e.g., Zn2+, Fe3+, Cu2+, Ni2+, Pb2+, Al3+) is sparse. An incorrect conclusion can be reached by the student that practical EDTA titrations are only performed at high pH. In addition, widening the window of possible metal ions for complexometric titration affords the possibility of analyzing real world products, such as the cold lozenges discussed in the article.

Analysis of the Essential Nutrient Strontium in Marine Aquariums by Atomic Absorption Spectroscopy: An Undergraduate Analytical Chemistry Laboratory Exercise

An undergraduate atomic absorption spectroscopy (AAS) laboratory experiment is presented involving the analysis of the essential nutrient strontium in a real-life sample, sea water. The quantitative analysis of strontium in sea water is a problem well suited for an undergraduate analytical chemistry laboratory. Sea water contains numerous components which prevent the direct quantitative determination of strontium. Students learn first hand about the role of interferences in analytical measurements, and about the method of standard addition which is used to minimize these effects. This laboratory exercise also introduces undergraduate students to practical problems associated with AAS. We encourage students as a part of this experiment to collect and analyze marine water samples from local pet shops.

A Study of the Oxidation Pathway of Adrenaline by Cyclic Voltammetry: An Undergraduate Analytical Chemistry Laboratory Exercise

An undergraduate laboratory exercise to be used in an undergraduate instrumental methods course is presented for the electrochemical characterization of oxidation products of adrenaline. An objective of this experiment is to use information obtained through cyclic voltammetry and simulation software to develop a qualitative understanding of the oxidation mechanism of adrenaline.

A new approach to undergraduate analytical chemistry

A new approach to undergraduate analytical chemistry

Enantiomeric Separation of Beta-Blockers by High Performance Liquid Chromatography: An Undergraduate Analytical Chemistry Experiment

Experimental procedure to familiarize students with the principle and application of high performance liquid chromatography (HPLC) to separate isomers of a common pharmaceutical; includes data and analysis.

Marine microcosm - using an aquarium to teach undergraduate analytical chemistry

Marine microcosm - using an aquarium to teach undergraduate analytical chemistry

Problems of teaching undergraduate analytical chemistry

Some problems of teaching undergraduate analytical chemistry are outlined and discussed. As a model the teaching scheme and contents of some courses concerning basic analytical chemistry at the Masaryk University, Brno, and the Charles University, Prague, are given.

Fundamentals of Analytical Chemistry. Sixth edition (Skoog, Douglas A.; West, Donald M.; Hollar, James F.)

This textbook is designed for one- or two- semester undergraduate analytical chemistry courses.

Determination of components in beverages by thin-layer chromatography: An undergraduate analytical chemistry experiment

This is a description of a simple and interesting thin layer chromatography experiment using three different fluorescence detection principles for the determination of caffeine, saccharin, and sodium benzoate in beverages.

Undergraduate analytical chemistry: inducing a metamorphosis

Undergraduate analytical chemistry: inducing a metamorphosis

Determination of aspartame, caffeine, saccharin, and benzoic acid in beverages by high performance liquid chromatography: An undergraduate analytical chemistry experiment

Separations can be applied to the analysis of soft drinks, artificial sweeteners, fruit juices, and coffee.

A study of the liquid-liquid partitioning process using reverse-phase liquid chromatography: An undergraduate analytical chemistry experiment

This experiment promotes an interpretation of the molecular aspects of solute partitioning, thus offering the student a more complete understanding of separation science in general and liquid chromatography in particular.