Period of Performance: 04/15/1991 - 03/31/1992


Phase 1 SBIR

Recipient Firm

Potomac Photonics, Inc.
4445 Nicole Drive
Lanham, MD 20706
Principal Investigator


High-performance capillary electrophoresis and microbore liquid chromatography offer extremely high efficiencies, ultra-small sample injection, and speed of analysis. However, the general utility of these new technologies is limited by the sensitivity of the detector. Ultraviolet-transmission detectors are shown to be inherently incapable of the sensitivity and dynamic range necessary for a wide range of biochemical separation applications. Very recently Potomac Photonics, Inc., introduced a series of small, relatively inexpensive mid-to-far-UV waveguide excimer lasers. We show that these lasers provide an ideal pump source for a technique known as crossed-beam photothermal refraction detection. This technique has been demonstrated capable of ~3 orders of magnitude better sensitivity than the best UV-transmission detectors. No chemical derivitization of the analyte is necessary to achieve maximum sensitivity. In Phase I, we propose to build a detector based on photothermal refraction and to employ a proprietary krypton fluoride waveguide excimer laser operating at 249 nm to demonstrate detection of unmodified oligonucleotides separated by capillary electrophoresis. We intend to demonstrate ~100 times greater sensitivity than that available from UV-transmission detectors being used for HPCE systems. Such a detector will have a broad array of applications such as genetic testing and engineering, pharmaceutical purity testing, as well as forensic pathology and DNA fingerprinting.