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 tissue -> brain

Citations 12

"Calixarene-coated Amperometric Detectors"
Anal. Chim. Acta 1994 Volume 294, Issue 2 Pages 201-206
Joseph Wang* and Jie Liu

Abstract: Calixarene coatings were shown to impart high selectivity into the amperometric detection of neurotransmitters (e.g. dopamine, epinephrine) while excluding common electroactive interferences (e.g. ascorbic and uric acids, acetoaminophen). A polished Pt disc electrode (1.5 mm diameter) was coated by placing 5 µL of 2 mg/ml C-undecylcalix[4]resorcinarene in tetrahydrofuran on to the electrode and allowing the solvent to evaporate (5 min). The electrode was evaluated in a FIA system at a working potential of 0.6 V vs. Ag/AgCl (3 M NaCl) reference electrode and with 0.05 M phosphate buffer (pH 7.4) as the carrier solution (1.5 ml/min). The response to epinephrine was linear for 10^-80 µM and the detection limit was 3 µM (27 ng). The RSD (n = 24) for the detection of 0.1 mM dopamine was 1.6%. The electrode did not respond to 0.1 mM acetaminophen, 0.1 mM ascorbic acid or 0.1 mM uric acid. The coating was stable under vigorous hydrodynamic conditions and maintained its permselective properties over prolonged periods, > 6 h.
Dopamine Epinephrine Amperometry Sensor Electrode Interferences

"Flow Injection Analysis With An Enzyme Reactor Bed For Determination Of Ascorbic Acid In Brain Tissue"
Anal. Chem. 1983 Volume 55, Issue 14 Pages 2439-2440
Charles W. Bradberry and Ralph N. Adams

Abstract: A new ascorbic acid (I) assay is described which is highly suitable for determination of I in brain tissue in the presence of catecholamines and metabolites. In this method, a soluble sample containing I plus other electrooxidizable substances is passed over an inactive reactor bed to generate a peak amperometric signal that is proportional to the sum of all the concentrations Then the same injection is passed through an active bed which contains ascorbate oxidase immobilized on Sepharose, and the I is selectively removed, producing a smaller signal. From precalibrations, the difference between the 2 signals is an accurate measure of I. An amperometric detector allows very low level determinations of I. The technique is adaptable to the determination of I in a variety of samples and was used to determine 2.07 µmol I/g rat brain caudate nucleus.
Ascorbic acid Amperometry Clinical analysis Potentiometry Immobilized enzyme Reactor

"Selective Determination Of Histamine By Flow Injection Analysis"
Anal. Chem. 1990 Volume 62, Issue 18 Pages 1971-1976
James M. Hungerford, Kevin D. Walker, Marleen M. Wekell, Jack E. LaRose, and Harold R. Throm

Abstract: A flow injection analysis (FIA) method for the determination of histamine is described. Control of reaction timing allows exploitation of a transient, chemical-kinetic increase in selectivity that occurs when o-phthalaldehyde reacts with histamine. The molar fluorescence ratio (selectivity) of histamine/histidine reaches a maximum value of 800 in 32 s, precluding the need for separation of histamine from histidine, spermidine, and other potential interferences in biological samples. Online dilution prevents matrix effects and affords a linear response up to approximately 4.45 mM histamine, or 500 mg of histamine free base/100 g. Under these conditions the detection limit (3 times peak-to-peak baseline noise) is 5.5 pg (corresponding to 0.60 mg of histamine free base/100 g of sample) and throughput is 60 injections per hour. The high sensitivity and high selectivity of the method allow the rapid determination of histamine in fish with minimal sample conditioning and will find application in the determination of endogenous histamine as well, such as in blood plasma and brain tissue.
Histamine Fluorescence Kinetic Selectivity Interferences Dilution Detection limit

"Determination Of Tin In Biological Samples Using Gaseous Hydride Generation - Inductively Coupled Plasma Atomic Emission Spectrometry"
Anal. Biochem. 1990 Volume 190, Issue 1 Pages 71-77
Katsuhiko Yokoi, Mieko Kimura and Yoshinori Itokawa

Abstract: Liver, brain, testis or kidney was homogenized and heated with HNO3 and HClO4 in Kjeldahl flasks until white fumes appeared. Water was added with heating until the solution was clear and colorless. An aliquot of the solution was treated with trichloroacetic acid (I) and diluted with water to 0.2% in I. This solution was mixed, in a continuous-flow hydride-generation system (diagram given), with 1% I solution and then with 0.5% NaBH4 in 0.1% NaOH solution and passed through a gas - liquid separator (design presented) and the hydride, in an Ar-stream, was determined by ICP-AES at 189.989 nm. The limit of detection was 30 pg mL-1 of Sn, mean recovery was 87 to 99% and the coefficient of variation was 1.2%.
Tin Spectrophotometry Dilution Phase separator Detection limit Volatile generation Volatile generation Kjeldahl

"Determination Of Catechols In The Presence Of Ascorbic Acid And Uric Acid By Flow Injection Analysis Employing A Potentiometric Dibenzo-18-crown-6 Electrode Detector"
Anal. Lett. 1994 Volume 27, Issue 11 Pages 2141-2151
Lunsford, S.K.;Galal, A.;Akmal, N.;Ma, Y.L.;Zimmer, H.;Mark, H.B.

Abstract: A polished Pt disc electrode was modified by the electropolymerization of dibenzo-18-crown-6 (DB-18-C-6) on to its surface using an applied potential of +3.2 V (vs. Ag/AgCl) for 5 min in an electrolyte containing 0.025 M DB-18-C-6 and 200 mM tetrabutylammonium tetrafluoroborate. The modified electrode and a Ag/AgCl reference electrode were mounted in a thin-layer flow cell of a FIA system. The potentiometric response of the electrode to catechol and catecholamine was measured using a 20 µL injection loop and 0.1 M potassium phosphate buffer of pH 9.4 as the mobile phase (1 ml/min). The calibration graph was linear for 1 µM to 10 mM catechol and the detection limit was 0.5 µM. Similar results were obtained for the neurotransmitters. Interferences from ascorbic acid and uric acid were not significant until the concentration of the interferent exceeded a 10-fold excess.
Catechols Electrode Electrode Potentiometry Interferences

"Flow Injection Analysis Of Nitrite Generated By Neutrophils And Endothelial Cells"
Anal. Lett. 1994 Volume 27, Issue 15 Pages 3081-3093
Hybertson, B.M.;Dunham, A.J.;Thompson, D.C.;Terada, L.S.;Repine, J.E.

Abstract: Solutions from cultures of bovine pulmonary artery endothelial cells or human neutrophils were injected via a 100 µL sample loop into a stream of 0.1 M NaI/0.1 M H3PO4. The mixture flowed into microporous tubing (20 cm x 1 mm i.d.) in a glass bulb with gas inlet and outlet parts. He gas was swept through the bulb at ~100 ml/min and into a Nitric Oxide Chemiluminescence Analyzer (Sievers Instruments model 270B, Boulder, CO, USA). The calibration graph was linear for 10^-5000 nM-nitrite.
Nitrite Chemiluminescence

"Melittin-silica, A High-pressure Affinity Chromatography Resin For Calmodulin"
J. Chromatogr. A 1987 Volume 403, Issue 1 Pages 99-107
William S. Foster and Harry W. Jarrett

Abstract: The cited stationary phase for affinity chromatography of calmodulin(I) was prepared by coupling melittin to glycidyloxypropyl-silica. I was determined on a column (30 cm x 4.6 mm) of the cited resin with 10 mM sodium phosphate - 0.5 mM EGTA (pH 7.5) as mobile phase at 1 mL min-1 and detection at 230 nm. I was selectively bound in the presence of Ca(II) but not in its absence. With post-column derivatization with phthalaldehyde, <50 ng of I could be determined in brain or pea-plant extracts.
Calmodulin LC Sample preparation Spectrophotometry Post-column derivatization

"High Performance Liquid Chromatographic Determination Of Plasma And Brain Histamine Without Previous Purification Of Biological Samples: Cation-exchange Chromatography Coupled With Post-column Derivatization Fluorimetry"
J. Chromatogr. B 1985 Volume 344, Issue 1 Pages 115-123
Atsushi Yamatodani, Hiroshi Fukuda and Hiroshi Wada, Toshinao Iwaeda, Takehiko Watanabe

Abstract: Plasma and homogenized brain were extracted with HClO4 and the extracts were analyzed directly by HPLC on a column (10 cm x 6 mm) of TSK gel SP-2SW (5 µm) with 0.25 M KH2PO4 as mobile phase (0.6 mL min-1). After the elution of histamine(I), spermidine and other strongly basic compounds were eluted with 0.5 M KH2PO4. I was determined fluorimetrically at 450 nm (360-nm excitation) after online post-column derivatization with phthalaldehyde. The detection limit was 0.05 pmol of I, and the calibration graph was rectilinear for 10 pmol. Recovery was 98.5% and the within- and between-day coefficient of variation were <3%.
Histamine Spermidine HPLC Fluorescence Post-column derivatization

"Microassay For GM1 Ganglioside β-galactosidase Activity Using High Performance Liquid Chromatography"
J. Chromatogr. B 1988 Volume 426, Issue 1 Pages 75-82
M. Naoi and M. Kondoh, T. Mutoh, T. Takahashi, T. Kojima, T. Hirooka and T. Nagatsu

Abstract: Brain tissue homogenate was incubated, at 37°C for 1 h, with GM1 ganglioside in 50 mM citric acid - 100 mM sodium phosphate buffer (pH 4.4) containing 100 mM NaCl and 0.5% of Na taurodeoxycholate. After heating at 100°C for 2 min and cooling, mobile phase, viz, 0.5 M H3BO3 - NaOH buffer (pH 8.7) was added and the mixture was centrifuged. The supernatant solution was subjected to HPLC, at 65°C, on a column (25 cm x 4.0 mm) of Shimadzu ISA-07/S2504 at 0.6 mL min-1 and with post-column derivatization by heating the eluate with 2% L-arginine - 3% H3BO3 and after cooling, fluorimetric detection at 430 nm (excitation at 320 nm). The calibration graph was rectilinear for 1 mmol of β-galactose.
Enzyme, galactosidase HPLC Fluorescence Heated reaction Post-column derivatization

"Analysis Of Nitrite, Nitrate, And Nitric Oxide Synthase Activity In Brain Tissue By Automated Flow Injection Technique"
Methods Enzymol. 1996 Volume 268, Issue 1 Pages 152-159
Isao Yokoi, Hitoshi Habu, Hideaki Kabuto and Akitane Mori

Abstract: Automated flow injection analyzers of nitrite and nitrate (NOx) are widely used in the detection of environmental pollution. The principle of this method is dependent on Griess reaction for diazonium ion. This chapter describes an automated flow injection technique for nitrite and nitrate analysis in the brain and its application for determination of NOS activity in the brain.
Nitrate Nitrite

"Selective Determination Of Inorganic Mercury And Methylmercury In Tissues By Continuous-flow And Cold Vapor Atomic Absorption Spectrometry"
J. Anal. Toxicol. 1993 Volume 17, Issue 2 Pages 87-92
Raja H. Atallah and David A. Kalman

Abstract: A method has been developed for the determination of inorganic (InHg) and methylmercury (MeHg) in solubilized tissues with continuous-flow (flow injection) cold vapor atomic absorption spectrometry. Kidney, liver, and brain tissues were spiked with MeHg and InHg and solubilized at an elevated temperature in a solution containing 90 g/L NaOH, 2 g/L L-cysteine, and 4 g/L NaCl. Total mercury determination was achieved by continuous-flow cold vapor atomic absorption spectrometry using an inlet system containing a flow-through photo-oxidation reactor and sodium borohydride as the mercury reductant. InHg was selectively determined in the presence of MeHg with this method when using stannous chloride as the reductant. MeHg concentrations were computed as the difference between the values obtained from the two analyzes. Recoveries for spiked tissues were above 95% for InHg and MeHg. Quantitation limits for InHg and total mercury in tissues were 0.4 and 0.6µg/g, respectively. MeHg chloride levels from kidney tissues of exposed rats were evaluated using the present method in comparison with another method in which MeHg was measured using solvent extraction and capillary gas chromatography with electron capture detection. Kidney, liver and brain tissues (0.25 g) were spiked with methylmercury (I) or Hg (5 and 10 µg) and solubilized at 60°C in a solution containing 10 g L-1 of NaCl (4 ml), 10 g L-1 of L-cysteine (2 ml) and 450 g L-1 of NaOH (2 ml). For Hg determination, tissue (100 µL) was injected at 1.8 mL min-1 and treated with SnCl2 at 0.8 mL min-1 with a stream of N at 350 mL min-1. Total Hg was determined with use of a photo-oxidation modification step to convert I to Hg; sample was acidified with a stream of 6 M HCl containing K persulfate at 0.8 mL min-1 which provided online acidification of the solubilized solution before entering the photoreactor and reacting with NaBH4. Determination limits for inorganic Hg and total Hg were 0.4 and 0.6 µg g-1 in tissues, respectively. Recoveries were >95% for Hg and I by continuous-flow- and cold vapor-AAS.
Methylmercury ion Mercury Spectrophotometry Speciation Photochemistry Phase separator

"L-DOPA Does Not Facilitate Nitric Oxide Production In The Rat Striatum And Substantia Nigra: In Vivo Microdialysis Study"
Life Sci. 1998 Volume 63, Issue 4 Pages 59-64
Kenichi Kashihara*, Kenichi Sakai, Konosuke Marui and Toshikiyo Shohmori

Abstract: Using in vivo microdialysis and flow injection, we evaluated the production of nitric oxide (NO) in the striatum and substantia nigra of freely moving rats in response to challenge doses of L-dihydroxyphenylalanine (L-DOPA) by measuring the NO metabolite levels of nitrate and nitrite. The dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) concentrations also were determined in the same perfusates. Intraperitoneal injection of L-DOPA produced a significant, dose-dependent increase in the extracellular levels of dopamine and DOPAC in these areas, but did not modify the extracellular levels of the NO metabolites. An acute dose of L-DOPA does not appear to facilitate NO production in the rat striatum and substantia nigra.
Nitrogen monoxide In vivo monitoring