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Biomedical subjects

M S Freund

Publications and source records attributed to M S Freund.

6 recordsLinked to original sources
PubMed1999

Indirect electrochemical detection of type-B trichothecene mycotoxins.

Trichothecene mycotoxins in animal feed and human food can cause fatalities in livestock and disease in humans. In addition, these toxins are suspected chemical warfare agents. Therefore, development of a simple and sensitive method for the screening of trichothecenes is important to prevent economic loss and health hazards. A simple and inexpensive method for the detection of type-B trichothecene mycotoxins has been developed in our laboratory. By hydrolyzing the toxin under basic conditions at 80 degrees C for 1 h it is possible to detect the toxin with simple electrochemical techniques. Deoxynivalenol (DON), commonly known as vomitoxin, was used as a representative compound for type-B trichothecenes in this detection scheme. The detection limit for DON using our procedures was determined to be 9.1 microM in solution, corresponding to 0.24 ppm in a 25-g grain sample if the final extraction volume is 2.2 mL. The linear dynamic detection range was determined to be from 0.32 ppm to greater than 32 ppm. In addition to standard solutions, this method was used on rice samples spiked with DON. It was demonstrated that there is no electrochemical interference from rice extract and that 1 ppm of DON in rice samples can be quantified. This method may be ideal for toxin screening in animal feeds or in runoff from sites that produce the compounds as chemical warfare agents. Since the active moiety in DON is common to virtually all type-B trichothecenes, our approach may be ideal for type-specific screening.

Electrochemistry↗
PubMed1995

A chemically diverse conducting polymer-based "electronic nose".

We describe a method for generating a variety of chemically diverse broadly responsive low-power vapor sensors. The chemical polymerization of pyrrole in the presence of plasticizers has yielded conducting organic polymer films whose resistivities are sensitive to the identity and concentration of various vapors in air. An array of such sensing elements produced a chemically reversible diagnostic pattern of electrical resistance changes upon exposure to different odorants. Principal component analysis has demonstrated that such sensors can identify and quantify different airborne organic solvents and can yield information on the components of gas mixtures.

Journal Article↗
PubMed1991

Effect of electrode substrate on the morphology and selectivity of overoxidized polypyrrole films.

Polypyrrole (PP) films were electropolymerized on glassy carbon (GC) and rough pyrolytic graphite (RPG) electrodes and treated by overoxidation in sodium hydroxide and phosphate buffer. The effects of treatment on film morphology were investigated, including permselective response of treated films. Films grown on GC and RPG were also compared, and it was found that the substrate plays a definite role in the properties of the polymer layer. Differences in response to ionic probes on treated PP electrodes are shown to arise from the porosity of the membranes, which affects the electron density within the film due to the spacing of carbonyl groups introduced during treatment.

Electrodes↗
PubMed1989

Ultramicroelectrode array behavior of one-dimensional organic conductor electrodes.

Tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) electrodes were prepared by two methods that produced electrodes with different structures. This was confirmed by scanning electron microscopy, which also revealed the ultramicroelectrode arraylike structure of TTF-TCNQ electrodes. Electrochemical behavior at both types of electrodes followed the predictions of the theory for ultramicroelectrode arrays. At the two types of surfaces that were prepared, apparent electrochemical rate constants of ferricyanide and ascorbate were different. The resulting changes in the apparent rate constants of redox couples such as ferricyanide and ascorbate as a function of surface structure suggest that at TTF-TCNQ control over reactivity can be achieved through structural manipulation.

Electrochemistry↗