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Finite dose diffusion studies: II. Effect of concentration and pH on NAA penetration through isolated tomato fruit cuticles
Author(s) -
Knoche Moritz,
Bukovac Martin J
Publication year - 2000
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/1526-4998(200012)56:12<1016::aid-ps253>3.0.co;2-8
Subject(s) - penetration (warfare) , chemistry , penetration rate , citric acid , aqueous solution , chromatography , acetic acid , analytical chemistry (journal) , biochemistry , organic chemistry , geotechnical engineering , operations research , engineering
The effects of NAA [2‐(1‐naphthyl)acetic acid] concentration and pH on penetration of NAA from aqueous droplets (5 µl) through isolated tomato ( Lycopersicon esculentum ) fruit cuticles were studied using a finite dose diffusion system. Penetration time‐courses were characterized by a lag phase, which generally extended beyond the time of droplet drying. Initially penetration rates increased, reached a maximum penetration rate, remained constant for several hours, and then decreased with time. Penetration approached a plateau within 120 h after droplet application. Increasing NAA concentration in the donor droplet increased NAA penetration in both the presence and absence of the citric acid buffer (20 m M , pH 3.2). Maximum rates of penetration and the total amount of NAA that penetrated at 120 h were both linearly related to the initial concentration of the donor droplet (ranging from 0.001 to 0.1 m M NAA). The apparent first‐order rate constants for the concentration dependence of NAA penetration rates were greater with buffer than without (0.94 × 10 −8 vs 0.50 × 10 −8 m s −1 , respectively). While pH of the receiver solution (pH 6.2 vs 2.2) did not affect penetration, decreasing donor pH from 6.2 to 2.2 increased NAA penetration at 120 h. © 2000 Society of Chemical Industry