James "Rip" Kirby, USF, of The Emerald Coast Chapter of Surfrider, a beach advocacy organization, has published a report wherein UV light was used to screen for BP oil, which was largely dispersed with Corexit 9500A/9527.
The UV light-at-night shows dramatic results, but is not sufficient; the report details some false negatives were found for deeper sands when samples were analysed in the lab Mass Spec and chemically (photo pg 14).
from the abstract.
"The use of ultraviolet light equipment in the ﬁeld showed distinct ﬂuorescent responses to illumination by a 370nm UV light source. UV light equipment was found to be very efﬁcient in identifying tar product on the beach for evaluating the visual level of contamination on the beach. Fluorescent responses from tar product found in the ﬁeld and laboratory created tar product were measured by ﬂuorometry equipment."
from the conclusion
"The presence of Corexit® brand dispersant treated crude oil as provenance for weathered tar product can be determined by examining its ﬂuorescent response to 370nm wavelength UV light. The ﬂuorescent response, or signature, of the tar product shifts toward red as the amount of dispersant increases. Thus, higher ratios of dispersant to crude oil used during clean up operations can be subjectively determined.
Published research conﬁrms that microbial degradation of tar product is inhibited by the presence of Corexit® dispersant still bound to its molecular structure. Finding tar product using UV light is a proven solution to improving physical removal methods. "
~20 pages of text and diagrams, 220 pages total. most of it is report data. contact info for Kirby and Erica Canales of Surfrider is in the chain of custody paperwork.