Development of an instrument to detect trace elements in food, beverages and biological samples

This paper presents a method of detecting trace elements in food, beverages and biological samples in real-time. The instrument is based on Electron Spin Resonance and Fresnel Zone break point. It is shown that an unknown sample, placed between the transmit and the received antenna, separated by a distance less than the Freznel Zone break point, absorbs electromagnetic energy at a frequency determined by the atomic weight of the unknown sample. The Freznel Zone break point is used to position the antennas in order to avoid multipath signals. A prototype instrument along with experimental data is presented to illustrate the concept.