No abstract

Rhenium can be determined by atomic absorption in a fuel-rich acetylene-oxygen flame, using either de or ac electronics. Use of an organic solvent increases the sensitivity. Proper burner placement in the optical path is critical. Using three burners in a single-pass optical system, with optimum conditions, 1–2 ppm rhenium is readily detectable.

in a Mobile Spectroscopy Laboratory T. A. ~e h m a n , and T. D. ~o b e r k ' .~ I Previouslv3 a mobile snectroscovv laboratorv has been described as-a means by which smauk; schools may cooperate so as to provide for their students a laboratarv experience with more expensive spectroscopic and chromaiogrHphic instruments. In order to stimulate others to try this cooperative venture the types uf chemiwy experiments which are posiihl~ and which have been ac~ually used u,ill be drscrihed in this paper.The first point to be stressed is that exotic andlor odd experiments are not necessary for use in the truck-laboratory. The usual experiments are easily done. For example the major use of these instruments has been to solve "unknowns"at a11 levels of instruction. Such work requires the student to learn to onerate the instrument correctlv. obtain the data. and then . .interpret the data-the usual use of instruments by chemists. This practice is especially apparent in second semester sophomore organic courses where the student uses ir, nmr, and mass spectroscopy to deduce the structure of simple "unknowns." Demonstrations of the use of these instruments are often provided for non-science majors and visiting high school students. The usual detailed instructions on how to use the instruments are reserved for science maiors. (These are the students who will use the instruments in semesters to come and often are very helpful in setting up the laboratory when it arrives. Often these same students can give demonstrations and teach new students how to use the instruments.)Freshman students in general chemistry can easily he taught to use the atomic absorption spectrometer. Analysis of tap water from various sources illn&ates wide variation in concentrations of heavy metals such as lead, zinc, and copper. Analyses of calcium and magnesium concentrations show the "hardness" of water and that "water softeners"real1y work. Two other exneriments that became auick favorites involve analyses of hkavy metals in &ffereut ci'garette brands and analyses of the concentration of sodium and potassium in urine and blood. Students supply samples in each case.Freshman students also have utilized the ultraviolet-visible spectrometer to monitor air quality. Air is pumped through solutions containing trapping reagents for sulfur dioxide, nitrogen dioxide, or ozone. The increase in ultraviolet or visible absorption can be easily related to concentration. Heavy metals such as iron or manganese in samples taken from rivers, lakes, and streams can also be extracted bv trapping rewents and analyzed in the same way. Nitrate a i d &%&ate-concentrations have also been checked using this method.A popular demonstration for freshmen has been the determination of 32SP4S in nature by use of the mass spectrometer. Carbon disulfide is often the sample which is used. If possible an upperclassman carries out the actual demonstration.In addition to the "unknowns" which are solved by sophomores as mentioned above, the organic laboratory utilizes the flame-ionization ...