Finite dose diffusion studies

I. Characterizing cuticular penetration in a model system using NAA and isolated tomato fruit cuticles

authored by: Moritz Knoche, Martin J. Bukovac
Abstract: A finite dose diffusion system was employed to study cuticular penetration of 2-(1-naphthyl) [1-¹⁴C]acetic acid (NAA) from simulated spray droplets through enzymatically isolated tomato fruit cuticles (Lycopersicon esculentum Mill cv Pik Red). Isolated cuticles were mounted on diffusion half-cells with the cell wall surfaces facing a 20mM citric acid receiver solution (pH 3.2, volume 2.9ml, prepared with deionized water). A 5-μl donor droplet containing NAA at 100 μM in 20mM citric acid buffer (pH 3.2) was applied to the outer surface. Penetration was monitored by repeated sampling of the receiver solution. NAA penetration was characterized by (1) an initial lag phase of about 2.3 h, (2) a phase of nearly constant maximum rate of penetration averaging 6.3% of applied NAA h^-1 (equivalent to 0.032nmol h^-1) and (3) a plateau phase approaching an asymptote at 81.2% of applied NAA (equivalent to 0.406nmol) at 120h. Within 1h after application droplets appeared dry on visual inspection. Immediately after droplet drying, 7.0% of the applied NAA was sorbed to the cuticle, but only 0.5% penetrated into the receiver solution, indicating that penetration occurred almost exclusively from tire apparently dry deposit. At 120h, 5.2% of the NAA applied was associated with the deposit and 4.3% with the cuticle. The distribution of maximum rates of penetration was lognormal, but penetration at 120 h followed a normal distribution. Cuticle thickness (estimated 5-25 μm) had no significant effect on NAA penetration. Maximum rates of penetration through pepper fruit and citrus and ficus leaf cuticles were 4.9-, 2.6- and 0.1-times that through tomato fruit cuticles. At 120h, penetration averaged 85.5, 79.5 and 34.7% for pepper, citrus and ficus cuticles, respectively. Extracting epicuticular and embedded waxes increased NAA penetration rates through tomato fruit cuticle more than three-fold, but had little effect on penetration at 120h (71.0 vs 87.7% for cuticular vs dewaxed cuticular membranes). The maximum penetration rate and total penetration were found to be useful parameters in describing the penetration time-course. (C) 2000 Society of Chemical Industry.
External Organisation(s): Michigan State University (MSU)
Martin Luther University Halle-Wittenberg
Type: Article
Journal: Pest management science
Volume: 56
Pages: 1005-1015
No. of pages: 11
ISSN: 1526-498X
Publication date: 2000
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Agronomy and Crop Science, Insect Science
Electronic version(s): https://doi.org/10.1002/1526-4998(200012)56:12<1005::AID-PS188>3.0.CO;2-Y (Access: Open)

BibTeX

@article{543768894461431c929107e3a33a67cc,
title = "Finite dose diffusion studies: I. Characterizing cuticular penetration in a model system using NAA and isolated tomato fruit cuticles",
abstract = "A finite dose diffusion system was employed to study cuticular penetration of 2-(1-naphthyl) [1-14C]acetic acid (NAA) from simulated spray droplets through enzymatically isolated tomato fruit cuticles (Lycopersicon esculentum Mill cv Pik Red). Isolated cuticles were mounted on diffusion half-cells with the cell wall surfaces facing a 20mM citric acid receiver solution (pH 3.2, volume 2.9ml, prepared with deionized water). A 5-μl donor droplet containing NAA at 100 μM in 20mM citric acid buffer (pH 3.2) was applied to the outer surface. Penetration was monitored by repeated sampling of the receiver solution. NAA penetration was characterized by (1) an initial lag phase of about 2.3 h, (2) a phase of nearly constant maximum rate of penetration averaging 6.3% of applied NAA h-1 (equivalent to 0.032nmol h-1) and (3) a plateau phase approaching an asymptote at 81.2% of applied NAA (equivalent to 0.406nmol) at 120h. Within 1h after application droplets appeared dry on visual inspection. Immediately after droplet drying, 7.0% of the applied NAA was sorbed to the cuticle, but only 0.5% penetrated into the receiver solution, indicating that penetration occurred almost exclusively from tire apparently dry deposit. At 120h, 5.2% of the NAA applied was associated with the deposit and 4.3% with the cuticle. The distribution of maximum rates of penetration was lognormal, but penetration at 120 h followed a normal distribution. Cuticle thickness (estimated 5-25 μm) had no significant effect on NAA penetration. Maximum rates of penetration through pepper fruit and citrus and ficus leaf cuticles were 4.9-, 2.6- and 0.1-times that through tomato fruit cuticles. At 120h, penetration averaged 85.5, 79.5 and 34.7% for pepper, citrus and ficus cuticles, respectively. Extracting epicuticular and embedded waxes increased NAA penetration rates through tomato fruit cuticle more than three-fold, but had little effect on penetration at 120h (71.0 vs 87.7% for cuticular vs dewaxed cuticular membranes). The maximum penetration rate and total penetration were found to be useful parameters in describing the penetration time-course. (C) 2000 Society of Chemical Industry.",
keywords = "Absorption, Deposit, Droplet, Foliar uptake, Naphthylacetic acid",
author = "Moritz Knoche and Bukovac, {Martin J.}",
year = "2000",
doi = "10.1002/1526-4998(200012)56:12<1005::AID-PS188>3.0.CO;2-Y",
language = "English",
volume = "56",
pages = "1005--1015",
journal = "Pest management science",
issn = "1526-498X",
publisher = "John Wiley and Sons Ltd",
number = "12",
}