Spectroscopy-01-01-2016

We wrap up our introduction to the theory of infrared spectral interpretation with a discussion of the correct process to follow when interpreting spectra. The author has developed this 12-step system over many years of interpreting spectra, and finds it gives him the best results. The process includes knowing how a spectrum was measured, systematically identifying peaks, and the proper use of infrared spectral interpretation aids. The answer to last column’s quiz is also disclosed.

Pages 22–35 Rapid detection of coal and fly ash is significant to improve the efficiency of thermal power plants and reduce environmental pollution. Given its fast response, high sensitivity, real-time, and noncontact features, laser-induced breakdown spectroscopy (LIBS) has a great potential for on-line measurement in these applications. The direct measurement of particles and gases using LIBS was studied, and the method was shown to be effective for this application. 

Signal suppression caused by matrix effects has long presented challenges to analysts using inductively coupled plasma–atomic emission spectrometry (ICP-AES) and inductively coupled plasma–mass spectrometry (ICP-MS) techniques. In some cases, however, matrix effects enhance the signal, and thus benefit the analysis. Guillermo Grindlay of the University of Alicante, in Spain, has been studying signal enhancement by charge-transfer reactions resulting from the presence of carbon, sulfur, and phosphorus in the sample matrix. His aim is to better understand under what conditions these matrix effects occur and what mechanisms are involved, to assist analysts in managing interferences and improving the analytical figures of merit in their work. He recently spoke to us about his research.

To get better performance from inductively coupled plasma (ICP)-based methods, it is informative to study the properties of the ICP under different conditions. Annemie Bogaerts and Maryam Aghaei at the University of Antwerp, Belgium, are using computational modeling to examine how various properties of the ICP, such as gas flow path lines and velocity, temperature changes, and ionization effects, are affected by numerous factors, such as the gas flow rates of injector and auxiliary gas, applied power, and even the very presence of an MS sampler. They have also applied their models to study particle transport through the ICP. Using their developed model, it is now possible to predict optimum conditions for specific analyses. Bogaerts and Aghaei spoke to us about this work.

In this paper, we demonstrate a sensitive surface-enhanced Raman spectroscopy (SERS) substrate for trace dimethoate detection. The substrate is composed of Ag nanoparticle/probe/smooth Au film stack configuration. The nanogap formed by an Ag nanoparticle and a macroscopically flat Au film is one kind of “hot site” which will dramatically increase the total “hot spots” number.

Uwe Karst of the University of Münster in Germany discusses his group’s work using ICP-MS for applications such as analyzing magnetic resonance imaging (MRI) contrast agents in river water, speciation analysis in a study of a disease related to renal failure, and examining the distribution of a labeling compound in mouse tumor cells and macrophages.

Click the title above to open the Spectroscopy January 2016 regular issue, Vol 31 No 1, in an interactive PDF format.