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: Biological fluid -> milk -> human

Citations 7

"Speciation Of Copper And Manganese In Milk By Solid Phase Extraction/inductively Coupled Plasma-atomic Emission Spectrometry"
Anal. Chim. Acta 1998 Volume 375, Issue 3 Pages 299-306
O. Abollino, M. Aceto*, M. C. Bruzzoniti, E. Mentasti and C. Sarzanini

Abstract: A speciation method was developed to study distribution of Cu and Mn species in cow milk. The method is based upon solid phase extraction of selective fractions of the analytes, followed by elution and determination by inductively coupled plasma-at. emission spectrometry (ICP-AES), using it as a flow injection detector. Fractions detected were cationic, anionic, neutral and casein-bound. A different behavior is observed for the 2 metals.
Copper Manganese Spectrophotometry Speciation Solid phase extraction

"Amperometric Determination Of Lactose In Human And Cow's Milk Using A Flow Injection System With Some Immobilized Enzyme Reactors"
Electroanalysis 1989 Volume 1, Issue 4 Pages 413-416
Toshio Yao*, Reina Akasaka, Tamotsu Wasa

Abstract: A bioelectrochemical flow-injection system is proposed for the determination of lactose in milk from humans and cows. The system includes an amperometric flow-through platinum electrode to measure hydrogen peroxide, which was enzymatically generated by injecting a 10-L sample into the packed-bed reactors of immobilized -galactosidase and glucose oxidase that are incorporated in series in the flow line. Because the presence of glucose interfered with the measurement of lactose, a precolumn packed with coimmobilized glucose oxidase and catalase was positioned just before the two immobilized enzyme reactors to remove the glucose from the milk. The peak current was linearly related to the lactose concentration between 0.01 and 2.0 mM. The determinations of lactose in milk could be performed at a rate of 60 samples/h with satisfactory precision (less than 0.8% RSD) and no pretreatment except for the sample dilution.
Lactose Amperometry Reactor Injection technique Immobilized enzyme

"Determination Of Ochratoxin A At The Ppt Level In Human Blood, Serum, Milk And Some Foodstuffs By High Performance Liquid Chromatography With Enhanced Fluorescence Detection And Immunoaffinity Column Cleanup: Methodology And Swiss Data"
J. Chromatogr. B 1995 Volume 666, Issue 1 Pages 85-99
Bernhard Zimmerli* and Rudolf Dick

Abstract: An improved specific analytical method for ochratoxin A (OA) is presented, combining HPLC separation with enhanced fluorescence detection by post-column addition of ammonia. Commercial immunoaffinity columns (Biocode) were for the first time applied to the cleanup of extracts of body fluids; they could be used up to 20 times for blood serum. The extraction efficiency of OA from human serum and milk as well as its derivatization to esters were studied and improved. The quantitation limit for OA was improved and estimated at 5-10 pg/g for human milk and serum. The mean recovery of OA from serum and milk was estimated at 85%. The overall coefficient of variation for OA determinations in serum, milk and selected foodstuffs was estimated at 10% (concentration range 0.01-5 ng/g). The method was applied to sera of 368 blood donors, 10 pairs of maternal and fetal sera, as well as to 40 human milk samples and selected foodstuffs; the results are discussed.
Ochratoxin A HPLC Fluorescence Post-column derivatization

"Determination Of Vitamin B6 In Foods And Other Biological Materials By Paired-ion High Performance Liquid Chromatography"
J. Agric. Food Chem. 1985 Volume 33, Issue 3 Pages 359-363
Jesse F. Gregory and Debra Feldstein

Abstract: Food, human plasma or milk, or rat liver or muscle samples, were homogenized in sulfosalicylic acid with 4'-deoxypyridoxine (as internal standard) and CH2Cl2. After centrifugation, the aqueous phase was applied to a column of Bio-Rad AG2-X8 anion-exchange resin (200 to 400 mesh; Cl- form) with 0.1 M HCl as mobile phase. The fraction containing pyridoxine was subjected to HPLC on a column (3 cm x 4.6 mm) of octadecylsilica (3 µm) with gradient elution with 0 to 2.5% of propan-2-ol in 33 mM potassium phosphate - 8 mM octanesulfonic acid (pH 2.2). Post-column derivatization was with NaHSO3 in 1 M sodium phosphate buffer (pH 7.5) and fluorescence detection was at 400 nm (excitation at 330 nm). The coefficient of variation were <2%; recoveries were 78.7 to 103.2%. Good correlation with published data was achieved.
Vitamin B6 Pyridoxine HPLC Ion exchange Fluorescence Post-column derivatization

"Optimization Of Selenium Determination In Human Milk And Whole Blood By Flow Injection Hydride Atomic Absorption Spectrometry"
J. AOAC Int. 1998 Volume 81, Issue 2 Pages 457-461
Amparo Alegr&iacute;a, Reyes Barber&aacute;, Rosaura Farr&eacute;, Emilia Ferrer, M. Jes&uacute;s Lagarda, M. Angeles Torres

Abstract: A flow injection hydride atomic absorption spectrometric (FI-HAAS) method was developed for determining selenium in human milk and whole blood after microwave digestion of the sample. The sample (2 mL human milk or 0.25 mL blood) was introduced into the microwave vessel with 1.5 mL HNO3 and 0.25 mL H2O2 and 300 W (4 min) and 600 W (4 min) were applied. The digestion was completed by heating to 140°C (2-3 h). Se(VI) was reduced to Se(IV) with HCl. The instrumental conditions for FI-HAAS (concentrations of reducing agent and carrier acid, flow rate of Ar carrier gas, and sample volume injected) were optimized. The detection limit of the proposed method was 0.23 ng/mL (assay) or 115 pg Se (abs.) in biological samples (1.15 ng/mL milk, 10.4 ng/mL blood). The precision values were 5.0% for milk and 4.0% for blood. The accuracy was evaluated with two NIST reference materials. Non-Fat milk powder (found: 104.3 ± 7.2 ng/g, certified: 110 ± 10 ng/g) and whole blood seronorm (found: 81 ± 7.3 ng/mL, ref.: 83 ± 4 ng/mL). The results show the suitability of the method for Se determination in human milk and whole blood. The method was applied to whole blood samples obtained from pregnant women and to human milk.
Selenium Spectrophotometry Sample preparation Reference material Optimization

"An Automated Microtechnique For Selenium Determination In Human Body Fluids By Flow Injection Hydride Atomic Absorption Spectrometry"
J. Trace Elem. Electrolytes Health Dis. 1990 Volume 4, Issue 1 Pages 41-48
Negretti de Bratter VE, Bratter P, Tomiak A

Abstract: The automation of a flow injection system for the hydride generation of selenium and its subsequent determination by atomic absorption spectrometry (FI-HAAS) is described. Pre-treatment of the sample and the details of the automated equipment are reviewed. For the FI-HAAS selenium analysis a volume of 350 µL of acid-digested sample solution is injected. The online generated hydride is delivery by the gas-liquid separator and is transported together with an Ar stream to the heated quartz cell for the atomic absorption determination. The absolute detection limit is 35 pg Se; the relative detection limit 0.10 µg/L Se. The absolute determination limit in real biological samples is 110 pg Se; the relative detection limit 0.31 µg/L Se. The accuracy of the method was evaluated via analysis of certified standard reference materials. Quality control was made by comparing FI-HAAS and instrumental neutron activation analysis (INAA), as an independent analytical method. Two acid-digestion procedures (in open vessels at atmospheric pressure and bomb-digestion in pressure vessels) were experimentally tested. To determine the effectiveness of the selenium reduction and the completeness of the selenium hydride formation a parallel selenium determination was carried out by means of ICP-AES and FI-HAAS analysis. FI-HAAS was applied for blood serum analysis of children undergoing long-term total parenteral nutrition, as well as of persons with high dietary selenium intake, and for human milk analysis. Human serum or milk (150 µL) is digested overnight with 1 mL of concentrated HNO3, a further 1 mL of HNO3 is added, and the sample is ashed for 1 h at 170°C. After addition of 100 µL of H2SO4 and 50 µL of HClO4, the sample is ashed for a further 1.5 h. Alternatively bomb-digestion is performed for 5 h at 160°C. The digest is diluted to 3 mL with 5 M HCl and heated at 95°C for 30 min for reduction of Se(VI) to Se(IV). A 350 µL portion of this solution is injected into a water carrier stream (2.2 mL min-1) that is subsequently mixed with streams of HCl (2.2 mL min-1) and alkaline 3% NaBH4 (0.44 mL min-1). The reaction mixture is passed into a gas - liquid separator and the H2Se formed is swept by Ar (0.3 l min-1) into a heated silica tube, where it is atomized at 900°C for detection of Se at 196.0 nm. Calibration graphs are rectilinear for 0.87 to 8.7 ng of Se injected and the limit of detection is 0.1 µg l-1. Results for four biological standard reference materials (including NBS Bovine Serum and Oyster Tissue) agreed well with certified values. Results for Se in human serum or milk generally agreed well with those obtained by instrumental NAA.
Selenium Sample preparation Spectrophotometry Automation Detection limit Reference material Calibration Phase separator Volatile generation Method comparison Review Volatile generation

"Iron And Copper Content Of Human Milk At Early Stage Of Lactation In Venezuelan Woman"
Trace Elements Med. 1988 Volume 5, Issue 2 Pages 60-63
Burguera, M.; Burguera, J. L.; Garaboto, A. M.; Alarcon, O. M. (SFS)

Abstract: The Fe and Cu content of early milk from 30 Venezuelan mothers was examined. A total of 210 samples were collected at 5-day intervals starting 1 day postpartum for one month. Each sample was acid digested in a Parr bomb and its Fe and Cu content was determined by flow injection/atomic absorption spectroscopy. Concentration of both elements decreased significantly at successive stages of lactation with Fe showing the greatest decline. Fe and Cu contents were 64.2±8.1 and 115.1±8.7 µg/100 mL the first day post partum, and 9.8±0.8 and 20.0±2.2 µg/100 mL one month postpartum, respectively.
Copper Iron Spectrophotometry