Instrumentation, high-throughout

Recently, a new (and now commercially available) methodology was reported for measuring in-situ high pressure NMR spectra up to 50 bar under stationary conditions. The instrument uses a modified sapphire NMR tube, and gas saturation of the sample solution and exact pressure control is guaranteed throughout the overall measurement, even at variable temperatures. For this purpose, a special gas cycling system is positioned outside the magnet in the routine NMR laboratory [51]. 

Kenneth Johnson is a Senior Scientist at the Monterey Bay Aquarium Research Institute. His research interests are focused on the development of new analytical methods for chemicals in seawater and application of these tools to studies of chemical cycling throughout the ocean. His group has developed a variety of analytical methods for analyzing metals present at ultratrace concentrations in seawater. His expertise lies in trace metal analysis and instrumentation. The creation of reference materials to calibrate these instruments is important for the production of long-term, high-precision datasets. Dr. Johnson has participated on the NRC Committee on Marine Environmental Monitoring and the Marine Chemistry Study Panel. 

Life testing conducted on N0 SPE sensor cells showed a 1 /day increase in signal over the first 20 to 30 days followed by a leveling in performance. Typical initial sensor response for the NO sensor cell is 3 /ppm N0. With daily- calibrations, high accuracy levels can be maintained throughout sensor life. For example, a prototype N0 detection instrument has operated for one year with the response to N0-in-air within 15 of the original calibration value. 

The blowpipe is a narrow tube through which a stream of air can be blown. When applied to a flame, it produces a fine jet at a high temperature. Jewelers, glass workers, and craftsmen working with metal had used the instrument since antiquity, and it had remained a tool of skilled artisans for thousands of years before it was used in chemistry. In the eighteenth century it came into wide use as a specifically chemical instrument, first in Sweden and then, over the next half-century and more, throughout the rest of Europe. 

High-performance liquid chromatography does similar things with more sophisticated instrumentation. It can separate closely related chemical compounds on a research scale or on a preparative scale liquid solvents, or mixtures of several solvents under positive pressure, replace the "carrier gas" of Fig. 11.3. The solid support must have small particle sizes (3- to 10-pm diameter), so that relatively high pressures can be sustained throughout the column, and it is at the interface between the liquid eluant and the solid particles that the chromatographic separation is accomplished. 

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