Biomedical subjects

J A Reffner

Publications and source records attributed to J A Reffner.

4 recordsLinked to original sources

PubMed2001

Comparison of transmission and internal reflection infrared spectra of cocaine.

Comparing the infrared transmission spectrum of cocaine HCl to its attenuated total reflection (ATR) spectrum has raised questions about the use of ATR spectra for forensic drug analysis. Whenever infrared spectra are collected using different modes or sample preparation methods, small variations in peak intensity ratios or peak positions are possible. These variations in infrared spectra are small and do not interfere with qualitative analysis, but they can cause confusion when unrecognized as normal effects of the different spectroscopic techniques. Comparison of the absorption and ATR spectra of cocaine hydrochloride illustrates the type of differences that can be expected. These differences are explained by the fundamental differences in the collection techniques. For the best quantitative results, only spectra collected by the same technique should be compared.

Journal Article↗

PubMed2001

Single fiber analysis by internal reflection infrared microspectroscopy.

Attenuated total reflection (ATR) is a convenient mode for single fiber analysis by infrared microspectroscopy, particularly when transmission spectra are difficult to obtain or when surface preferenced sampling is desirable. Textile finishes such as spin finishes, anti-static finishes, and permanent press finishes are revealed by ATR techniques. Bicomponent fibers may be analyzed by a combination of ATR techniques, transmission techniques, and spectral subtraction.

Journal Article↗

PubMed1998

Instrumental factors in infrared microspectroscopy.

Instrumentation is the cornerstone of infrared microspectrometry (IMS) technology and the foundation for all applications. The fundamental factors in IMS systems are presented from the perspective of an instrument developer. While the current state of instrument development is presented, speculation of future development is also included. The goal of IMS instrumentation is to produce the highest signal-to-noise ratio (SNR) spectrum with the highest spectral resolution from the smallest sample area. Detector response, spectrometer efficiency, source brightness, wavelength range, microscope optics and sample definition are factors limiting IMS instrument performance. The current performance and future trends in IMS instrumentation are presented in this work.

Humans↗

PubMed1988

Infrared spectroscopy of a single cell--the human erythrocyte.

Methods for obtaining the infrared spectrum of a single erythrocyte by infrared microscopy have been developed. The spectrum contains the amide I, II, and III bands characteristic of protein secondary structure near 1650, 1550, and 1300 cm-1, respectively. Bound carbon monoxide exhibits a readily measured band at 1951 cm-1 for 12C16O and 1907 cm-1 for 13C16O. Both amide and CO bands are similar to those found for purified hemoglobin A. Spectra can be obtained in H2O or D2O media under physiologically relevant conditions. Single cell infrared spectroscopy (SCIR) permits the qualitative and quantitative determination of differences among individual red cells. These results suggest many potential applications for SCIR for the measurements of properties of individual cells at the molecular level under physiologically relevant conditions.

Carbon Monoxide↗