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: Agricultural -> grain

Citations 5

"Rapid Determination Of Zinc And Iron In Foods By Flow Injection Analysis With Flame Atomic Absorption Spectrophotometry And Slurry Nebulization"
Talanta 1990 Volume 37, Issue 7 Pages 711-718
João Carlos de Andrade*, Frederick C. Strong, III and Nadir J. Martin

Abstract: A rapid method of determining zinc and iron in food by flame atomic absorption spectrophotometry with slurry nebulization into an air-acetylene flame has been developed. A V-groove, clog-free Babington-type nebulizer, coupled to a single-line flow injection analysis (FIA) system, was employed to introduce the slurry into the spray chamber. Under the FIA conditions described, an injection frequency of 120/hr is possible, with negligible carry-over and memory effects. The calibration graphs were obtained by using various concentrations (up to 0.1 g/ml) of white bean homogenate as standards, rather than solutions. The method has been applied to various kinds of foods, including grains, vegetables, fruits and sausage. Homogenization of semi-prepared samples to form slurries took only 4 min. Relative deviations between results by the slurry and solution methods for both elements averaged 2-3%. Detection limits by the slurry method were 0.3 µg/ml Zn and 0.6 µg/ml Fe. A V-groove, Babington-type nebulizer, coupled to a single-line flow injection analysis system, was used to introduce sample slurry into the spray chamber for AAS determination. An injection frequency of 120 h-1 was possible, with negligible carry-over and memory effects. Calibration graphs were obtained by using 0.1 g mL-1 of white bean homogenate as standards. Homogenization of semi-prepared samples to form slurries took 4 min. Of air - acetylene and air - propane flames for the AAS, the former was preferred due to its rectilinear calibration graph. Relative deviations of results by slurry and solution methods for both Zn and Fe were 2 to 3%. Detection limits for the slurry method were 0.3 and 0.6 µg mL-1 of Zn and Fe, respectively. The method was applied to various foods, including grains, vegetables, fruits and sausage.
Iron Zinc Spectrophotometry Nebulizer Slurry

"Flow Injection Fluorimetric Determination Of Nabam And Metham"
Talanta 1996 Volume 43, Issue 2 Pages 193-198
Tomás Pérez-Ruiza,*, Carmen Martínez-Lozanoa, Virginia Tomása and Rocio Casajúsa

Abstract: Cereal grain was dried in the sun for 1 h and in the shade for 24 h. The grain was ground, mixed with 0.1 M NaOH, sonicated for 10 min and centrifuged for 5 min at 2000 rpm. The filtered supernatant or diluted natural water was injected into a carrier stream (0.3 ml/min) of pre-mixed streams of 0.3 M HCl and 0.2 mM TlCl3 in 0.5 M HCl. The resulting stream passed through a reaction coil [100 cm for nebam or 150 cm for metham (metam) x 0.5 mm i.d.] and the fluorescence intensity was measured at 419 nm (excitation at 227 nm). Calibration graphs were linear for 1-10 µM-nabam and metam with RSD (n = 10) at 3 and 7 µM of 1.4 and 0.8%, respectively, for nabam and 1.2 and 0.5%, respectively, for metam. The effects of foreign substances on the analysis are tabulated and discussed. Recoveries of nabam from water were 96.6-104% and 95.75-104% from cereals with corresponding recoveries for metam of 96.6-105% and 95-101.6%.
Methylcarbamodithioic acid Nabam Fluorescence Interferences

"High Performance Liquid Chromatographic Method For Determining Trichothecene Mycotoxins By Post-column Fluorescence Derivatization"
J. Chromatogr. A 1987 Volume 410, Issue 2 Pages 427-436
Akira Sano, Satoshi Matsutani, Masao Suzuki and Shoji Takitani

Abstract: The procedure used for the extraction and cleanup of the mycotoxins from cereal samples was essentially that of Tanaka et al. (Food Addit. Contam., 1985, 2, 125), except that a Sep-Pak CN cartridge rather than a Sep-Pak silica cartridge was used in the final stage. HPLC was carried out on a column (25 cm x 4 mm) packed with LiChrosorb RP-18 (10 µm), preceded by a guard column (LiChroCART RP-18), with a mobile phase (1 mL min-1) of aqueous 15% acetonitrile. The eluate was mixed first with 0.15 M NaOH (0.5 mL min-1) for passage through a PTFE reaction coil (8 m x 0.5 mm) at 115°C, and then with 30 mM methyl acetoacetate - 2 M ammonium acetate (0.5 mL min-1) for passage through a second PTFE reaction coil (6 m x 0.5 mm) at 115°C. After cooling, the fluorescence was monitored at 460 nm (excitation at 370 nm). The calibration graphs for deoxynivalenol, nivalenol and fusarenone were rectilinear with corresponding detection limits of 5, 5 and 10 ng; coefficient of variation were 0.6 to 5.4%. The recoveries of 0.05 to 1 ppm of deoxynivalenol and nivalenol added to cereals were 79.6 to 96.9 and 61.4 to 90.6%, respectively.
Deoxynivalenol Nivalenol HPLC Fluorescence Heated reaction Post-column derivatization

"A Simple Quantitative HPLC Method For Determination Of Aflatoxins In Cereals And Animal Feedstuffs Using Gel-permeation Chromatography Clean-up"
Food Addit. Contam. 1989 Volume 6, Issue 1 Pages 35-48
Hetmanski MT, Scudamore KA

Abstract: A 25-g powdered sample was shaken for 30 min with Hyflo Supercel filter aid (13 g), water (12.5 ml) and CH2Cl2 (125 ml), and the mixture was filtered. The residue was washed with CH2Cl2 (3 x 25 ml), and the combined filtrate and washings were evaporated to incipient dryness under N. The residue was dissolved in 10 mL of CH2Cl2 - hexane (3:1), and a 5 mL aliquot was cleaned up on a column (50 cm x 2.5 cm) of Bio-Beads S-X3; the column was washed (4 mL min-1) with CH2Cl2 - hexane (3:1), and 5 mL fractions were collected. Fractions 17 to 22 were evaporated under N, the residue was re-evaporated from CH2Cl2 and a solution of the residue in aqueous 50% acetonitrile (2 ml) was analyzed by HPLC on a column (25 cm x 4.6 mm) of Spherisorb ODS 1 (5 µm). The mobile phase (0.75 mL min-1) was water - acetonitrile - methanol (6:3:1), and fluorescence detection at 440 nm (excitation at 360 nm) was used after post-column derivatization with iodine. Recoveries of aflatoxins from wheat, maize and feeds were 80, 70 and 65%, respectively. The determination limit was 1 µg kg-1.
Aflatoxins GPC HPLC Fluorescence Post-column derivatization

"Liquid Chromatographic Determination Of Aflatoxins, Ochratoxin A And Zearalenone In Grains, Oilseeds And Animal Feeds By Post-column Derivatization And Online Sample Cleanup"
J. AOAC Int. 1989 Volume 72, Issue 2 Pages 336-341
Chamkasem N, Cobb WY, Latimer GW, Salinas C, Clement BA

Abstract: Cereal, oilseed or animal feed (50 g) was extracted with aqueous acetonitrile - KCl - H3PO4 for 1 h, and the extract was filtered, diluted with water, and analyzed (0.3 ml) on an Econosphere C18 (5 µm) column (15 cm x 4.6 mm) equipped with a cleanup pre-column (5 cm x 4.6 mm) of Adsorbosphere C18 (10 µm) and operated with gradient elution (details given) with 5 mM Na2HPO4 buffer (pH 3.7), methanol and acetonitrile at 1.5 mL min-1 and post-column derivatization with saturated aqueous iodine in a reaction coil at 90°C for fluorimetric detection at 425 nm (excitation at 360 nm). Calibration graphs were rectilinear for up to 300 ppb of aflatoxins B1, B2, G1 and G2 and ochratoxin A and up to 1000 ppb of zearalenone in the samples; the corresponding limits of determination were 5 and 30 ppb.
Aflatoxin B1 Aflatoxin B2 Aflatoxin G1 Aflatoxin G2 Ochratoxin A Zearalenone HPLC Fluorescence Sample preparation Post-column derivatization Buffer PPB