University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Classification: Vegetable -> carrot

Citations 3

"Determination Of Carbamate Residues In Crop Samples By Cholinesterase-based Biosensors And Chromatographic Techniques"
Anal. Chim. Acta 1998 Volume 362, Issue 1 Pages 59-68
Gilvanda Silva Nunes*, Petr Skládal, Hideko Yamanakacand Damiá Barceló

Abstract: An amperometric biosensor based on cholinesterase (ChE) has been used for the determination of selected carbamate insecticides in vegetable samples. The linear range of the biosensor for the N-methylcarbamates (aldicarb, carbaryl, carbofuran, methomyl and propoxur) varied from 5 x 10^-5 to 50 mg kg-1. Limits of detection were calculated on the basis that the ChE enzymes were 10% inhibited and varied, depending of the combination ChE (as acetyl- or butyrylcholinesterase) vs. inhibitor (pesticide), from 1 x 10^-4 to 3.5 mg kg-1. The biosensor-based carbamate determination was compared to liquid chromatography/UV methods. Three vegetable samples were spiked with carbofuran and propoxur at 125 µg kg-1 followed by conventional procedures. Good correlations were observed for carbofuran in the vegetable extracts (79, 96 and 91% recoveries for potato, carrot and sweet pepper, respectively), whereas for propoxur unsatisfactory results were obtained. Potato and carrot samples were spiked with 10, 50 and 125 µg kg-1 carbofuran, followed by direct determination by the amperometric biosensor. The fortified sampler; resulted in very high inhibition values, and recoveries were: 28, 34 and 99% for potato, and 140, 90 and 101% for carrot, respectively, at these three fortification levels.
Ammonium carbamate hydrate Amperometry Sensor Method comparison

"Flow Injection Extraction-spectrophotometric Determination Of Copper With Dithiocarbamates"
Anal. Sci. 1990 Volume 6, Issue 3 Pages 415-420

Abstract: Several dithiocarbamates were investigated as reagents for the determination of Cu, and a flow injection method was developed. Sample solution (300 µL) in aqueous NH3 buffer (pH 8.5) as carrier solution was mixed with 0.05% Pb diethyldithiocarbamate in CHCl3, and passed through a coil (400 cm x 0.5 mm). The phases were separated in a membrane separator, and the absorbance of the organic phase was measured at 436 nm. The detection limit is 0.04 ppm of Cu, and the calibration graph is rectilinear up to 2 ppm. The method was applied to water and plants; results were precise and accurate.
Copper Spectrophotometry Sample preparation Extraction Buffer pH Mixing Membrane Organic phase detection Detection limit Calibration

"An HPLC Detection System For Phenylurea Herbicides Using Post-column Photolysis And Chemical Derivatization"
J. Chromatogr. Sci. 1985 Volume 23, Issue 11 Pages 516-520
Luchtefeld, R.G.

Abstract: Thirteen such herbicides (mostily chloro-compounds) are separated on a column (25 cm x 4.6 mm) of Alltech C18 with a guard column (5 cm x 2 mm) of Perisorb RP-18. The mobile phase is acetonitrile - water with gradient elution from 30 to 80% of acetonitrile in 30 min, at 1 mL min-1. The compounds in the eluate are photochemically degraded by UV radiation to produce methylamine, which reacts with a reagent containing phthalaldehyde - 2-mercaptoethanol to produce fluorescence that is measured at 455 nm (excitation at 340 nm). The response is rectilinear for all compounds in the range 2 to 48 ng. The method was applied to a carrot extract.
Herbicides, phenylurea HPLC Fluorescence Sample preparation Photochemistry Post-column derivatization