A study conducted by high school advanced bacteriology students appears to confirm the hypothesis that the incremental administration of antibiotics on several species of bacteria (Escherichia coli, Staphylococcus epidermis, Bacillus sublitus, Bacillus megaterium) will allow for the development of antibiotic-resistant strains. (PEB)

Describes sensitive and specific methods used to monitor tetrachlorodibenzodioxins and tetrachlorodibenzofurans. The procedures are suitable for detecting and quantifying these substances at the parts-per-trillion levels in complex environmental and biological samples. (Author/JN)

Discusses the nature and applications of mass-selective laser photoionization. The ionization can be done with a single intense laser pulse lasting a few billionths of a second with no molecular fragmentation. Applications focus on: (1) benzene clusters, excimers, and exciplexes; (2) metal clusters; and (3) triplet formation and decay. (Author/JN)

Free radical chlorination of methane is used in organic chemistry to introduce free radical/chain reactions. In spite of its common occurrence, demonstrations of the reaction are uncommon. Therefore, such a demonstration is provided, including background information, preparation of reactants/reaction vessel, introduction of reactants, irradiation,…

Discusses chemometrics (analysis of data from chemical measurements), tracing developments in this area and summarizing reasons for teaching chemometrics. Includes highlights of presentations given at a symposium (Interpreting Complex Chemical Data: Teaching Chemometrics) and brief descriptions of chemometric methods. (JN)

Describes an experiment on the qualitative analysis of several over-the-counter analgesic tablets. Background information, procedures used (including high pressure liquid chromatography), and typical student results are included. (JN)

The reaction between arsenite and iodate in acidic solution offers an excellent pedagogic introduction to such phenomena as traveling waves. Component reactions, traveling waves, and a mathematical model are discussed. Demonstrations described can easily be elaborated into a full laboratory experiment. (Author/JN)

A Beckmann arrangement was developed which explores the concept of stereospecificity and concurrently exposes students to synthetic, spectrophotometric, and chromatographic processes. Background information, laboratory procedures, and results are provided. (JN)