• Publications
  • Influence
Abiotic processes influencing fipronil and desthiofipronil dissipation in California, USA, rice fields
  • K. Ngim, D. Crosby
  • Medicine, Chemistry
    Environmental toxicology and chemistry
  • 1 May 2001
TLDR
The desthiofipronil observed in field water was formed photochemically from fipronsil, accumulated due to slower photolysis and lack of volatility from water, but eventually dissipated.
Multiresidue pesticide analysis in wines by solid-phase extraction and capillary gas chromatography-mass spectrometric detection with selective ion monitoring.
TLDR
A method was developed to determine pesticides in wines using capillary gas chromatography with electron impact mass spectrometric detection in selective ion monitoring mode (GC-MSD/SIM), and recoveries of less than 70% were most likely from pesticide polarity or lability.
Fate and kinetics of carfentrazone‐ethyl herbicide in California, USA, flooded rice fields
  • K. Ngim, D. Crosby
  • Medicine, Chemistry
    Environmental toxicology and chemistry
  • 1 March 2001
TLDR
Little is known of the environmental fate of the aryltriazolinone herbicide carfentrazone-ethyl (compound I), but Rice field applications of Shark 40D commercial formulation to duplicate 5.7 m2 rings produced pseudo-first-order half-lives of 6.5 to 11.1 h in water and 37.9 to 174 h in sediment.
The extraction and infrared identification of gamma-hydroxybutyric acid (GHB) from aqueous solutions.
TLDR
An alternative approach is presented here where GHB may be isolated as a free acid specie from complex aqueous solutions employing a liquid-liquid extraction technique that presents an infrared transmission spectrum that is sufficiently distinct for identification purposes.
Optimized procedures for analyzing primary alkylamines in wines by pentafluorobenzaldehyde derivatization and GC-MS.
TLDR
An optimized method for analysis in wines involving derivatization with pentafluorobenzaldehyde (PFB) to corresponding pentafloorobenzylimines, liquid-liquid extraction, and gas chromatography with mass selective detection is presented.
EFFECT OF SULFOBUTYL ETHER BETA-CYCLODEXTRIN MODIFIER ON SELECTIVITY OF REVERSED PHASE HPLC SEPARATIONS
TLDR
It is demonstrated that cyclodextrins and their derivatives are underutilized for HPLC and warrant consideration as a viable alternative to commercially available chiral or mixed mode columns.
Multiresidue determination of pesticides in malt beverages by capillary gas chromatography with mass spectrometry and selected ion monitoring.
TLDR
The study indicates that pesticide levels in malt beverages are significantly lower than the tolerance levels set by the United States Environmental Protection Agency for malt beverage starting ingredients.
Elucidation of fipronil photodegradation pathways.
TLDR
It is shown that II is formed directly and photochemically from I, confirmed by the greater stability of III (t(1/2) 112 h), and that successive oxidations of I to III and then a sulfonate (IV) comprise a second pathway.
Analysis of monoethanolamine by derivatization with Marfey's reagent and HPLC.
TLDR
This method is suitable for the determination of monoethanolamine at the 25 ppm level in drug substance, and the accuracy and precision obtained is 105.5 +/- 4.8% (n = 3).
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