Get A First Look At The Last Word In Materials Chemistry S taying informed on advancements in materials chemistry demands resources that let you read the latest research almost as it happens. Chemistry of Materials helps you do just that. Through a rigorous system of peer review, Chemistry of Materials brings what's new into clear, concise focus: •
New directions in molecular and ionic conductors, chemical processing of ceramics, non-linear optical materials, biomaterials, liquid crystals, and surface modified electrodes.
•
New materials including semi- and superconductors, composites, catalysts, ceramics, nanoporous solids and advanced polymers.
•
New processes, from MOCVD and plasma or laser-assisted deposition, to sol-gel processing.
Whether you're involved in advanced materials, R&D, chemical engineering, colloid and surface chemistry, analytical, physical, polymer chemistry or other relatedfields,Chemistry of Materials offers you an up-to-the-minute view of materials science and technology from a molecular-level perspective. A one-year subscription is only $50 for ACS members in the U.S. and includes 12 monthly issues. Nonmembers and abroad, call for subscription prices. To Subscribe: Call 1-800-333-9511 Outside the U.S. call 614-447-3776 Or write: American Chemical Society Publications Marketing 1155 16th Street, NW Washington, D.C. 20036 ACS ||| PUBLICATIONS Etumist Rnanrt.tf,, ,kr Oumiul So
EDITOR:
Leonard V. Interrante
Rensselaer Polytechnic Institute ASSOCIATE EDITORS
Dennis W. Hess, Lehigh University
Gary E. Wnek Rensselaer Polytechnic Institute
12 A
Analytical Chemistry, Vol. 67, No. 1, January 1, 1995
In AC
Research
ionic species and organic compounds in aqueous solutions. Although other emission spectroscopy methods can be used for sensitive metal ion detection, some of them exhibit poor selectivity between metals. Using a disulfide-modified 4-(2-pyridylazo)resorcinol coating and fiber-optic sensors, Keith Carron and colleagues at the University of Wyoming can determine and discriminate among Pb2+, Cu2+, and Cd2+ by resonance Raman spectroscopy at part-per-billion concentrations. ("SERS Surfaces Modified with a 4-(2-Pyridylazo)resorcinol Disulfide Derivative: Detection of Copper, Lead, and Cadmium"; AC940669M) Analyzing silicon nitride by ETAAS Digestion techniques used in the analysis of the ceramic material silicon nitride are time consuming, prone to contamination, and require the use of hazardous acids. Villiam Krivan and Klaus-Christian Friese at the Sektion Analytik und Hochstreinigung der University Ulm (Germany) report the application of slurry sampling electrothermal AAS to the determination of Al, Cr, Cu, Fe, K, Mg, Mn, Na, and Zn in silicon nitride powders. Quantification of all elements except Cu and Mn is possible with a calibration curve using aqueous standards. ("Analysis of Silicon Nitride Powders for Al, Cr, Cu, Fe, K, Mg, Mn, Na, and Zn by Slurry-Sampling Electrothermal Atomic Absorption Spectrometry"; AC9407173) Screening large IR databases w i t h neural networks Reducing the time required to identify each separated compound of a mixture from its IR spectrum offers the prospect of making the total analysis of unknown mixtures a less daunting task. Charles L. Wilkins and Christoph Klawun of the University of California-Riverside develop a new method of prefiltering that uses a back-propagation neural network to classify 609 matrix isolation FT-IR spectra with respect to the presence or absence of 35 functional groups. This information serves as sortable bit string keys to the spectral library, and they are used to construct a binary search tree for fast spectral retrieval. Compared with a sequential library search, this method yields a more than 25-fold increase in search speed. ("Neural NetworkAssisted Rapid Screening of Large Infrared Spectral Databases"; AC940876M) Graphite pretreatment and lead atomization GFAAS is often used to determine lead at ultratrace levels, but 0 2 is sometimes incorporated into the sheath gas as a matrix modifier to overcome background problems that can arise at low analyte concentrations, particularly when a biological matrix is present. To gain a better understanding of the processes involved, J. David Robertson, Corinne C. Eloi, and Vahid Majidi of the University of Kentucky use Rutherford backscattering spectrometry and scanning electron microscopy to investigate the interactions of lead as a function of temperature with a pyrolytically coated, H2 or 0 2 pretreated graphite flat. They report that although lead remains on the surface of the H2pretreated graphite surface, the migration of lead into the bulk of the pyrolytically coated graphite substrate is observed with Gypretreated and nontreated flats. ("Rutherford Backscattering Spectrometry Investigation of the Effects of Oxygen and Hydrogen Pretreatment of Pyrolytically Coated Graphite on Pb Atomization"; AC940734S)
