title: Determination of Stability from Multicomponent Pesticide Mixes.
abstract: A study was conducted to evaluate the stability of 528 pesticides, metabolites, and contaminants prepared in large multicomponent mixes to enhance laboratory efficiency by allowing maximum use of the useful shelf life of the mixtures. Accelerated aging at 50 °C simulated 6 month, 1 year, and 2 year storage periods at -20 °C. Initial mixture composition was based on the instrument of analysis. After preliminary stability data had been obtained, mixtures were reformulated and re-evaluated. In all, 344 compounds showed satisfactory stability across all treatment groups, 100 compounds showed statistically significant changes between the control and the 6 month simulated storage period (27 with losses >20%), and the remainder showed borderline stability or were tested in one protocol. Stability behavior for organophosphates agreed with the proposed reaction mechanism responsible for acetylcholinesterase inhibition. A small number of compounds increased in response over time, suggesting the occurrence of degradation of precursor pesticides into these respective compounds.
authors.affiliation: James Ford Bell Technical Center, Medallion Laboratories/General Mills Inc. , 9000 Plymouth Avenue N., Minneapolis, Minnesota 55422, United States.
authors.forename: Kelly J
authors.initials: KJ
authors.lastname: Dorweiler
authors.affiliation: Medallion Laboratories/General Mills Inc. , Spectra Building, Hiranandani Business Park, Powai, Mumbai 400076, India.
authors.forename: Jagdish N
authors.initials: JN
authors.lastname: Gurav
authors.affiliation: Supelco Division of Sigma-Aldrich , 595 North Harrison Road, Bellefonte, Pennsylvania 16823, United States.
authors.forename: James S
authors.initials: JS
authors.lastname: Walbridge
authors.affiliation: Medallion Laboratories/General Mills Inc. , Spectra Building, Hiranandani Business Park, Powai, Mumbai 400076, India.
authors.forename: Vishwas S
authors.initials: VS
authors.lastname: Ghatge
authors.affiliation: Medallion Laboratories/General Mills Inc. , Spectra Building, Hiranandani Business Park, Powai, Mumbai 400076, India.
authors.forename: Rahul H
authors.initials: RH
authors.lastname: Savant
mesh_terms: D004339:Drug Compounding; D004355:Drug Stability; D004356:Drug Storage; D007700:Kinetics; D010575:Pesticides / Q000737:chemistry*
chemical_list: D010575:Pesticides
keywords: accelerated aging; degradation; mass spectrometry; pesticides; stability