Randall B. Pugh

The use of chromophore and fluorophore degradation to quantitate UV dose: FD&C dyes as chemical identicators for UV sterilization.

The accurate measurement of ultraviolet (UV) irradiation, especially within a container or vessel is one of the challenges facing the broad implementation of UV sterilization. Currently, biological indicators are the best method to determine whether an applied UV dose has the necessary efficacy to achieve sterilization. To overcome some of the challenges of using a biological indicator, chemical indicators based upon the degradation of food, drug and cosmetic (FD&C) dyes were developed. In this work, the relationship between UV dose and dye degradation was elucidated and used to create standard curves which could be used as a quantitative measurement system. The use of dye degradation as a measurement of UV dose is especially useful when the levels of UV irradiation within a container cannot be measured directly. Additionally, due to the highly colored nature of the FD&C dyes, the visual changes present upon dye irradiation can be used as a qualitative visual indicator of the UV dose.

The efficacy of Acanthamoeba cyst kill and effects upon contact lenses of a novel ultraviolet lens disinfection system.

PURPOSE To assess the efficacy of a novel ultraviolet (UV) lens device on the killing of Acanthamoeba cysts and the impact of efficacious doses of UV upon soft contact lens parameter and material characteristics. DESIGN Prospective, in vitro, experimental study of a device. METHODS A UV lens device was constructed and used to expose Acanthamoeba cysts to various levels of UV irradiation. Once an efficacious dose, as defined by a greater than 3 log reduction, was determined (130 mJ/cm(2)), 6 soft contact lens materials (etafilcon A, senofilcon A, galyfilcon A, lotrafilcon A, polymacon, and comfilcon A) were exposed to that dose for 30 cycles and tested for visual parameters, mechanical parameters, and cytotoxicity. RESULTS The UV device produced an average log reduction of over 3.5 log of Acanthamoeba cysts when the lens and solution inside of the inset case was irradiated with 130 mJ per cm(2) of UV or greater. After 30 cycles of 130 mJ per cm(2) UV dose each, no gross changes were observed in mechanical properties or cytotoxicity tests in any soft contact lenses tested. In visual parameters, polymacon and lotrafilcon A exhibited a shift in sphere power and diameter, respectively. CONCLUSIONS The novel UV lens device was able to provide a marked log reduction to Acanthamoeba cysts, one of the most resistant ocular disease-causing organisms found in lens cases, without a detrimental effect on many lens materials.

A high-throughput microtiter plate based method for the determination of peracetic acid and hydrogen peroxide.

Peracetic acid is gaining usage in numerous industries who have found a myriad of uses for its antimicrobial activity. However, rapid high throughput quantitation methods for peracetic acid and hydrogen peroxide are lacking. Herein, we describe the development of a high-throughput microtiter plate based assay based upon the well known and trusted titration chemical reactions. The adaptation of these titration chemistries to rapid plate based absorbance methods for the sequential determination of hydrogen peroxide specifically and the total amount of peroxides present in solution are described. The results of these methods were compared to those of a standard titration and found to be in good agreement. Additionally, the utility of the developed method is demonstrated through the generation of degradation curves of both peracetic acid and hydrogen peroxide in a mixed solution.