EPR SPIN-LABEL TECHNIQUE AS AN ANALYTICAL TOOL FOR DETERMINING THE RESISTANCE OF REACTIVE TOPICAL SKIN PROTECTANTS (RTSPS) TO THE BREAKTHROUGH OF VESICANT AGENTS

Ointment formulations of reactive topical skin protectants (rTSPs) or topical skin protectants (TSPs) based on perfluorinated polyether mate rial (PFPE, i.e., fomblin RT-15) were prepared and spin labeled. Four N-oxyl-4-4'-dimethyloxazolidine derivatives of stearic acid, 5-NS, 7-N S, 12-NS, and 16-NS, were used as spin probes. The spin-labeled vehicl e, fomblin-RT-15, and vehicle containing chloroamide (S-330, an antive sicant) were exposed to various concentrations of half-mustard gas. Th e order parameter (S) was dependent on the depth of penetration of the paramagnetic group into the vehicle (fomblin) and on the chemical com position of the reactive antivesicant under investigation. The net cha nge of the viscosity of the vehicle and the chemical composition were seen to affect the penetration profile. This will provide a useful in vitro screening technique to develop antivesicant TSPs.