Solvent Contamination Determined by UV Reflection

Commercial organic cleaning solvents, unless specially prepared, may increase contamination of an item rather than clean it. A simple test to determine the presence or absence of a contaminant in a solvent can be performed by using ultraviolet-reflection spectroscopy. The procedure consists of immersing a quartz-paper coupon in a small quantity of the solvent to be tested, then evaporating the solution to dryness in a vent hood at room temperature. Prior to immersion, clean quartz paper typically reflects 70 to 90% of the ultraviolet in a range from 200 to 360 nm. If the filaments of the quartz-paper coupon have had any contaminant from the solvent deposited on their surfaces, the multi reflections produce an extensive ultraviolet absorption.