CONSIDERATIONS IN THE USE OF AN INFINITE-DOSE SYSTEM FOR STUDYING SURFACTANT EFFECTS ON DIFFUSION IN ISOLATED CUTICLES

The effect of Triton X-100 [TX-100, tyl)phenyl]-omega-hydroxypoly(oxy- 1,2-ethanediyl)] at concentrations below and above the critical micell e concentration (cmc, cmc = 0.019% w/w) on diffusion of 2-(1-[(14)]nap hthyl)acetic acid (NAA, 1 mu M) through isolated tomato (Lycopersicon esculentum Mill, cv. Pik Red) fruit cuticular (CM) and dewaxed cuticul ar membranes (DCM) was studied using an infinite-dose system. TX-100 s ignificantly increased time lags of NAA diffusion from 5 h (NAA only) and 5.8 h (0.01% w/v TX-100) to 7.4 h (0.1% TX-100) and 7.1 h (1% TX-1 00) when averaged over CM and DCM. Diffusion time lags in the absence and presence of TX-100 were greater for CM (6.1 h) than for DCM (5.2 h ). In CM, 0.01% TX-100 increased NAA flux, while 0.1% had no effect an d 1% TX-100 decreased the flux. In DCM, both 0.01 and 0.1% TX-100 enha nced the rate of NAA penetration, while flux was reduced in the presen ce of 1% TX-100. Two different approaches for calculating partition an d diffusion coefficients are presented, and their suitability for anal yzing effects of spray additives on cuticular penetration of an active ingredient is discussed using the example of TX-100 effects on NAA pe netration.