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
Email: schalk@unf.edu
Website: @unf

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Crop

Classification: Agricultural -> crop

Citations 4

"Determination Of Oxamyl And Methomyl By High Performance Liquid Chromatography Using A Single-stage Post-column Derivatization Reaction And Fluorescence Detection"
J. Agric. Food Chem. 1992 Volume 40, Issue 6 Pages 1026-1029
Steven C. Stafford and Willy Lin

Abstract: Dried, powdered apple, orange, soybean leaf and insect samples (0.5 g), fortified with oxamyl (I) and methomyl (II) were ground with pre-washed C18. The mixtures were packed into a column and, after washing with hexane, I and II were eluted with CH2Cl2, the eluates were evaporated to dryness, and the residues were reconstituted with water (pH 3) and sonicated. The solution, and also river water samples (1 ml), were filtered, then analyzed on a column (25 cm x 4.6 mm) of Zorbax ODS at 40°C with linear gradient elution at 1 mL min-1 with water (pH 3.0) - acetonitrile, programmed from (4:1) to (1:4) during 16 min. Single-stage post-column hydrolysis of the analytes, and derivatization of the methylamine produced, was performed in an online flow reactor at 140°C, with a mixture of o-phthalaldehyde in methanol, aqueous 0.01 M KOH and 2-mercaptoethanol as reagent. Fluorimetric detection was carried out at 455 nm (excitation at 340 nm). A schematic diagram of the post-column reactor is given. The recoveries of both I and II ranged from 72 to 129%, and detection limits were 20 ng g-1 (raw agricultural commodities) and 5 mg mL-1 (water).
Oxamyl Methomyl Fluorescence HPLC Post-column derivatization Heated reaction

"Immunoassay Of Pesticides: An Update"
J. AOAC Int. 1995 Volume 78, Issue 4 Pages 1079-1090
Bennett M. Kaufman and Marion Clower, Jr

Abstract: A review is presented to update information previously reported in 1991 (J. Assoc. Off. Anal. Chem., 1991, 74, 239) dealing with the measurement of pesticide levels in foods and crops by immunoassay. New immunoassays are discussed together with refinements of the common enzyme-based solid-phase assays such as use of coated magnetic particles, antibody-coated crystals and continuous-flow devices. (111 references). Measurement of levels of pesticide residues in foods and crops most often requires extensive cleanup and instrumental techniques such as gas chromatography. Immunoassay measurement techniques, on the other hand, may be used directly on the test portion or require only minimal cleanup. Further refinements of the common antibody-enzyme-based solid-phase assays, such as use of coated magnetic particles, antibody-coated crystals, and continuous-flow devices, have extended the measurement range and applicability of these assays. Likewise, new immunoassays for pesticides have been developed, and existing assays have been refined, optimized, and more completely characterized and validated. In addition to their ability to accurately and reliably measure amounts of residues present in food and crops, immunoassays can be readily used as rapid screening methods for contaminants in field samples. We have previously reviewed much of the work in the area of pesticide immunoassay; this report updates previous information and discusses some new immunoassay techniques.
Pesticides Immunoassay Review

"Rapid Determination Of HClO4-H2SO4 Degradation Nitrogen And Phosphorus In Farm Soils, Crops And Organic Manure Using Flow Injection Analysis"
J. Flow Injection Anal. 1993 Volume 10, Issue 2 Pages 224-235
Hideharu Nakajima *Ryoichi Yanagihara

Abstract: Sample (0.5 g) was decomposed with 25 mL of water, 3 mL of concentrated H2SO4 and 20.5 mL of HClO4 at 130°C for 10 min then heated to fuming at 200°C for 50 min. After cooling, water was added until the total weight was 50 g. To determine N, 30-200 µL of the supernatant was injected into the flow injection analyzer. and carried by a stream of 6% H2SO4 at 0.8 ml/min to mix with 2.5 M NaOH at 2 ml/min in a reaction tube at 30°C prior to reacting with a stream of Tecator NH3 indicator and detection at 590 nm. For P, 30-200 µL of the supernatant was carried by 6% H2SO4 at 2 ml/min to mix successively with 31 g/l of ammonium molybdate solution at 2.8 ml/min, water at 0.8 ml/min and 2% ascorbic acid at 0.8 ml/min with detection at 660 nm. For other samples vanadomolybdic acid was used instead of ammonium molybdate solution and ascorbic acid treatment, with detection at 420 nm. RSD for N and P were 2.1-5.4 and 1.8-8.6%, respectively. The results compared well with those obtained by other conventional methods.
Phosphorus Nitrogen Spectrophotometry Sample preparation Method comparison Tecator

"Rapid Method Of Determination For Total Phosphorus In The Crops And Organic Manure By HClO4-H2SO4 Digestion Flow Injection Analysis"
Tohoku J. Agric. Res. 1989 Volume 42, Issue NA Pages 171-172
Nakajima, H.;Kawashima, H.

Abstract: NA
Phosphorus Sample preparation