With support from the Major Research Instrumentation (MRI) Program, Roy Dixon and William DeGraffenreid in the Department of Chemistry at California State University in Sacramento will develop an aerosol charge detector (ACD) and an aerosol photoionization (APID)detector for high performance liquid chromatography (HPLC). In the aerosol-based detectors, the effluent from an HPLC will be converted to an aerosol, and subsequently charged and detected. In the case of the ACD, two approaches will be investigated: adaptation of a diffusion charger and construction of a detector using charging from spray electrification during the nebulization process. In the case of the APID, aerosol charging will occur during passage through a flow tube illuminated with ultraviolet light. Eluted compounds capable of photoionization will produce a positively charged aerosol. The charged aerosol in both detectors will be collected on filters connected electrically to an electrometer.
There is a strong need for inexpensive, universal and sensitive detectors for HPLC. A selective detector such as this with improved sensitivity over the ultraviolet-visible absorption detector will be useful in a number of applications. The investigators will use HPLC combined with these detectors to measure concentrations of polar organic compounds in atmospheric aerosols, to determine the structure and function of apolipoproteins, to investigate the ability of novel carbohydrate-containing compounds to inhibit HIV infection, and to measure dissolved solids in river water. Thus, these studies will have a significant impact in atmospheric, environmental and medicinal chemistry.
