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: Environmental -> water -> pond

Citations 12

"Spectrophotometric Determination Of Magnesium By Flow Injection Analysis With A Ligand Buffer For Masking Calcium"
Anal. Chim. Acta 1983 Volume 149, Issue 1 Pages 291-296
Hiroko Wada, Akio Yuchi and Genkichi Nakagawa

Abstract: 1-(2-Hydroxy-3-sulfo-5-chloro-1-phenylazo)-2-naphthol-3,6-disulfonic acid is used in a spectrophotometric flow-injection system for the determination of magnesium (0.2-2.4 mg l-1) at a sampling rate of 80 h-1. Interference of calcium is eliminated by using a barium-(II)-EGTA ligand buffer. Iron(III), aluminum(III), copper(II), zinc(II), manganese(II) and cadmium(II) are masked by cyanide and triethanolamine. The method is suitable for application to tap and pond waters.
Magnesium Spectrophotometry

"Solid-state Microprocessor-controlled Detector For Doublet Peak Measurements In Flow Injection Analysis"
Anal. Chim. Acta 1994 Volume 295, Issue 1-2 Pages 143-149
Mary K. Carroll, Michael Conboy, Asaph Murfin and Julian F. Tyson*

Abstract: In FIA a doublet peak occurs if the analyte concentration is too high when the centre of the sample plug reaches the detector. The time difference between the two peaks is proportional to ln concentration and use of the doublet can extend the working range. A detector is described using this principle. Sample solutions are injected into a tightly coiled mixing coil (60 cm x 0.9 mm i.d.) carrying the reagent and the solution passes through the detector unit with red, yellow and green ultrabright light-emitting diodes and emission centred at 630, 585 and 565 nm and mounted perpendicular to the flow direction. Opposite each is a photodiode detector. The flow cell is a square-section capillary (5 cm x 1 mm x 1 mm) with a sampled volume at each light source-detector pair of 1 µL. The whole unit is controlled by a microprocessor. The use was exemplified with a carrier stream (1.32 ml/min) of 10 µM-HCl containing 6 µM-bromothymol blue, injection of 0.011-110 mM NaOH and use of the red light source. The photodiode output was sent to a plotter, an oscilloscope or a computer. The calibration graph was linear over the whole range. Facilities also exist for several flow lines and for laser transmission or fluorescence measurements.
Indium Spectrophotometry Light emitting diode Photodiode

"Flow Injection Analysis Of Paraoxon With The Use Of An Immobilized Acetylcholinesterase Reactor"
Anal. Chim. Acta 1996 Volume 324, Issue 1 Pages 21-27
Renbing Shi and Kathrin Stein*

Abstract: A flow injection procedure for the determination of paraoxon as an example of organophosphorus pesticides based on inhibition of acetylcholinesterase immobilized on the polymer carrier VA Epoxy Biosynth was studied. The detection was carried out spectrophotometrically by means of enzymatic hydrolysis of acetylthiocholine iodide and reaction of the thiocholine from the enzymatic reaction with 5,5'-dithiobis(2-nitrobenzoic acid). Under optimal conditions for an inhibition time of 30 min the calibration graph was linear from 0.05 to 0.5 µg L-1 (r = 0.998, n = 5) with a relative standard deviation of 4.1% at 0. 1 µg l-1. For an inhibition time of 3 min the calibration graph was linear from 2 to 20 µg L-1 with relative standard deviation (n = 3) of 1.2% at 5 µg l-1. The inhibited enzyme was reactivated by 0.01 mol L-1 2-pyridinealdoxime methiodide. The recoveries from the samples to which paraoxon had been added (water, soil) were 104% and 94%, respectively. The determination of paraoxon was based on the inhibition of acetylcholinesterase. The sample solution was pumped (1.32 ml/min) for 3-30 min through an enzyme reactor (45 mm x 2 mm i.d.) packed with acetylcholinesterase immobilized onto polymer carrier VA Epoxy Biosynth. The valves were switched at the end of this inhibition time and a carrier stream of 1 mM Tris/6.64 g/l NaCl/1 g/l MgCl2 of pH 8.3 was passed through the reactor at the same flow rate. To measure the inhibition of the immobilized enzyme, 100 µL of 100 mg/l acetylthiocholine iodide was injected into the carrier stream and the liberated thiocholine was detected spectrophotometrically at 417 nm following reaction with 0.1 g/l 5,5'-dithiobis(2-nitrobenzoic acid) (0.56 ml/min). The enzyme reactor was regenerated with 0.01 M 2-pyridinealdoxime methiodide at 1.32 ml/min for 1.5 min. The calibration graphs for paraoxon were linear for 0.05-0.5 µg/l and 2-20 µg/l for inhibition times of 30 and 3 min, respectively. RSD (n = 3 or 5) were 4.1% (30 min) for 0.1 µg/l paraoxon and 1.2% (3 min) for 5 µg/l paraoxon. The recoveries for 0.1 µg/l paraoxon from spiked pond water and soil were >94% with 30 min inhibition time.
Paraoxon Pesticides, organophosphorus Spectrophotometry Immobilized enzyme Optimization Reactor

"Determination Of Chloride By Flow Injection Spectrophotometry With Membrane Reagent Introduction"
Anal. Chim. Acta 1998 Volume 366, Issue 1-3 Pages 147-153
Stuart J. Chalk and Julian F. Tyson*

Abstract: A single line manifold incorporating three Nafion membrane reactors was developed for the sequential introduction of components of the mercuric thiocyanate/Fe(III)/acid reagent for the determination of chloride. HNO3 was introduced at the 1st reactor to give sufficient ionic strength to allow cation exchange of FeSCN2+ at the 2nd reactor, and Hg2+ at the 3rd reactor. The composition of the reagent was adjusted by control of the flow rates of donor and acceptor streams, reagent concentration. and reactor length. Calibration over the range 0.3-25 µg mL-1 was possible, though the calibration function was curved. The manifold was used to determine chloride in river water and in pond water at concentrations. of 8 and 47 µg mL-1, respectively. and gave results that were not significantly different from those obtained by an EPA method. The lower range sensitivity was 0.032 absorbance µg mL-1, which compares favorably with that of other flow injection methods, but the detection limit was 300 ng mL-1, considerably higher than that can be achieved by flow injection procedures. This was due to the presence of mixing noise caused by fluctuations in reagent concentration. related to pulsations in the flow in both donor and acceptor streams. Valve switching and refractive index effects were absent.
Chloride Spectrophotometry Nafion membrane Membrane reagent introduction

"Permeation Tubes For Calibration In Flow Injection Analysis"
Analyst 1993 Volume 118, Issue 9 Pages 1227-1231
Stuart J. Chalk, Julian F. Tyson and Don C. Olson

Abstract: The use of a permeation tube for the production of liquid stream calibration standards in the flow injection determination of NH3 was investigated. The manifold (diagram and full description given) was constructed from 0.8-mm PTFE tubing, polyethylene ethyl ketone nuts and ferrules and PTFE unions. A six-port rotary inspection valve with 0.8-mm PTFE tubing connections was used for sample injection and the manifold was interfaced to the spectrometer using a 1-cm pathlength flow cell. An ammonia controlled-release Dynacal permeation tube with an active length of 5 cm was inserted into a 10 cm glass column; the carrier stream and permeation tube streams were 0.01 M HNO3. By varying the flow rate from 0.5 to 4 ml/min, calibration standards over the range 1.5-0.18 ppm could be obtained. The relationship between concentration. of the resulting solution and the reciprocal of the flow rate was linear. The manifold was applied to the determination of NH3 in pond water.
Ammonia Spectrophotometry Permeation tube Calibration Online standard generation

"Flow Injection Determination Of Anionic Surfactants With Cationic Dyes In Water Bodies Of Central India"
Analyst 1998 Volume 123, Issue 8 Pages 1691-1695
Rajmani Patel and Khageshwar Singh Patel

Abstract: A new, simple and specific flow injection analysis (FIA) procedure for the determination of anionic surfactants, viz., sodium lauryl sulfate (SLS), sodium dodecyl sulfonate, sodium hexadecyl sulfonate and sodium dodecyl benzenesulfonate, with cationic dyes, viz., Brilliant Green, Malachite Green, Methylene Blue, Ethyl violet and Crystal Violet, in water bodies, viz., ponds, tube wells, rivers and municipal wastes, of central India (east Madhya Pradesh) is described. It is based on the precipitation of the cationic dyes with the anionic surfactant due to formation of an ion-associated species within the pH range 5.5-8.0. The apparent molar absorptivity of the ion-associated species formed with various anionic surfactants and cationic dyes is in the range (0.60-1.50) x 104 L mol-1 cm-1 at λmax 590-665 nm. Among them, the pair BG+-LS- was selected for detailed investigation. The detection limit (amt. causing absorbance >3s) of the method with BG is 100 ppb SLS and the sample throughput is 50 h-1. Optimization of FIA and the anal. variables in the precipitation and determination of SLS with BG is described. The method is free from interferences from almost all ions which are commonly present with the surfactant. The proposed method was applied to the mapping of SLS pollution levels in the various water bodies. All surface waters and municipal waste waters and some ground waters lying near the sources were found to be contaminated with SLS beyond permissible limits.
Surfactants, anionic Sodium lauryl sulfate Sodium dodecyl sulfonate Sodium hexadecyl sulfonate Sodium dodecylbenzenesulfonate Spectrophotometry Ion pair formation pH Optimization Interferences

"Determination Of Total Mercury In Waters And Urine By Flow Injection Atomic Absorption Spectrometry Procedures Involving On- And Off-line Oxidation Of Organomercury Species"
Anal. Chem. 1993 Volume 65, Issue 5 Pages 653-656
Christopher P. Hanna, Julian F. Tyson, and Susan McIntosh

Abstract: Potable, river, pond or simulated waste water with added methylmercury chloride (20 ng mL-1 of Hg) was analyzed directly. Urine with Hg (100 ng mL-1) added as inorganic Hg, methylmercury chloride or phenylmercury acetate was either diluted with water and analyzed directly or treated with solid KMnO4 and H2SO4, clarified with 25% hydroxylammonium chloride and diluted with water for analysis. The sample was injected into water as carrier, and this stream was merged with concentrated H2SO4 in a 30-cm reaction coil. The resulting stream was merged with 5% K2S2O8 solution in a 150-cm coil, and 10% SnCl2 solution in 10% HCl was incorporated with passage through a 30-cm coil. Argon was introduced into the mixed solution, which passed through a further 30-cm coil and then through two gas - liquid separators, from the second of which the vapor passed to the AAS system for measurement at 253.7 nm. An amalgam system was used in parts of the study to trap the Hg on a Au - Pt gauze before thermal desorption and detection. No interference was caused by up to 2% of Cl- or up to 1 mg L-1 of S2- in the sample, and there was no problem from residual water vapor. The detection limit was 0.14 ng mL-1 of Hg, and the coefficient of variation (n = 3) was 1.4% at 10 ng mL-1 of Hg. Online oxidation afforded quantitative recovery of all forms of Hg added to water samples, but recovery of phenylmercury acetate from urine was 45% and that of methylmercury chloride was negligible, although inorganic Hg was fully recovered; off-line oxidation gave quantitative recovery of all species.
Mercury Methylmercury ion Phenylmercury Mercury(II) Spectrophotometry Speciation Amalgamation Interferences Volatile generation PPB Volatile generation

"Determination Of Trace Amounts Of Phosphate In Natural Water By Flow Injection Fluorimetry"
Anal. Lett. 1989 Volume 22, Issue 15 Pages 3081-3090
Wei, F.;Wu, Z.;Ten, E.

Abstract: Sample (50 µL) is injected into a carrier stream of water which then merges with merged streams fo 28 mM Mo(VI) - 0.8 M HCl and 20 µM-rhodamine 6G (C. I. Basic Red 1) - 0.025% of OP, and after passage through an 88-cm mixing coil the degree of fluorescence quenching at 550 nm is measured (excitation at 350 nm). The calibration graph is rectilinear for 100 ng mL-1 of P, and the detection limit is 2 ng mL-1. Only As(V) interferes, but can be masked by a 50-fold concentration. of S2O32-. Coefficients of variation (n = 12) for 10, 20 and 50 ng mL-1 of P were 5.4, 1.8 and 1.1%, respectively, and recoveries from tap-, well-, lake and pond water ranged from 92 to 102%.
Phosphate Fluorescence Quenching Interferences

"The Application Of Flow Injection Iminodiacetic Acid-ethylcellulose Membrane Preconcentration And Separation Technique To Atomic Spectrometry"
Spectrochim. Acta B 1998 Volume 53, Issue 10 Pages 1437-1445
Xiaoru Wang*, Zhixia Zuang, Chenlong Yang and Fan Zhyu

Abstract: A flow injection-based online iminodiacetic acid-ethylcellulose (IDAEC) membrane pre-concentration. and separation technique was developed, which has the advantages of easy operation without membrane plugging problems; a high enrichment factor (>10 for most elements); a high sample throughput (30 samples/h). The characteristics of the IDAEC membrane were systematically studied, including the effect of sample flow rate and analyte concentration. on break-through point; dynamic capacity and the lifetime of the IDAEC membrane. The technique was applied to pond water and seawater anal. in which all elements studied are in ng/mL level. The anal. performance was verified with recovery of a standard addition from seawater.
Spectrophotometry Membrane Preconcentration Standard additions calibration

"A Gravitational Phase Separator For Use In Flow Injection Liquid-liquid Extraction-indirect Atomic Absorption-spectrophotometric Determination Of Nitrate And Nitrite"
Fenxi Huaxue 1997 Volume 25, Issue 1 Pages 72-75
Qiu, H.O.;Shuai, Q.;Tang, Z.Y.;Lin, S.L.

Abstract: After treatment with Ce(IV) and pH adjustment to ~4, a 200 µL nitrate and nitrite mixture was injected via a FIA manifold equipped with a phase separator for extraction (diagram shown) into a carrier stream comprising 0.25 M KH2PO4 buffer of pH 4.5, 0.15 M hydroxylamine sulfate, 2.5 ml/l Cu(II) solution and water. The solution was reacted with 1.2 mM neocuproine in IBMK and the resulting ion pair formed was extracted for AAS determination of total nitrate and nitrite. For determination of nitrate, the nitrite was destroyed by sulfamic acid before carrying out the above procedure. Both main and auxiliary pumps were used at selected flow-rates, such as 2 ml/min. The pre-concentration factor was 26. The detection limit for nitrate was 28 µg/l. The RSD (n = 10) were The sampling frequency was 25 runs/h. The method was used to analyze pond water; recoveries ranged from 100-110%.
Nitrate Nitrite Spectrophotometry Sample preparation Phase separator MIBK Ion pair extraction Speciation Preconcentration Indirect

"Determination Of Imazethapyr Using Capillary Column Flow Injection Liposome Immunoanalysis"
J. Agric. Food Chem. 1996 Volume 44, Issue 12 Pages 4032-4036
Myoyong Lee and and Richard A. Durst

Abstract: A sensitive immunoanalysis system was developed for the quantitation of imazethapyr, the active ingredient in PURSUIT herbicide. Imazethapyr [5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid] is one of the imidazolinone class of herbicides. The assay was based on sequential competitive binding of imazethapyr and liposomes for a limited number of antibody binding sites. A capillary tube (20 cm x 0.53 mm i.d.) with immobilized antibody was used as the immunoreactor column. Liposomes that entrap fluorescent molecules as the detectable label provide instantaneous, rather than time-dependent, enhancement, common with enzyme immunoassays. In this study, liposomes encapsulated carboxyfluorescein dye and were made antigenic by incorporating in the bilayer a phospholipid that had the analyte conjugated to its polar head group. The calibration curve for imazethapyr in Tris-buffered saline solution had a working range of 0.1-100 ng/mL. In the range between 1 and 100 ng/mL, recoveries from fortified tap and pond water samples ranged from 93 to 114%. Filtration was the only step needed for sample cleanup, and an assay could be performed in <10 min.
Imazethapyr Immunoassay Liposomes

"Speciation Of Trace Metals In Pond Water As Studied By Liquid Chromatography/Inductively Coupled Plasma Mass Spectorometry"
Bull. Chem. Soc. Jpn. 1996 Volume 69, Issue 12 Pages 3469-3473
Akihide Itoh, Chisen Kimata, Hajime Miwa, Hideyuki Sawatari and Hiroki Haraguchi

Abstract: An on-line separation-detection system, liquid chromatography coupled with inductively coupled plasma mass spectrometry (ICP-MS), has been developed and applied to the study on speciation of trace metals in pond water. First, the total concentrations of dissolved metal ions in pond water were determined by ICP-MS after chelating resin pre-concentration. Then, pond water was pre-concentrated by ultrafiltration using a filter with a molecular weight permeation limit of 10000, providing size exclusion chromatography. Large organic molecules which had combined with trace metals in the pre-concentrated samples were separated with a gel filtration column and detected by UV absorption and ICP-MS, sequentially. In consequence, large organic molecules with the molecular weight of ≥300000 and 10000-50000 could be observed. A large number of trace metals (41 elements) were found in those organic molecules. Furthermore, the percentages of metal ions in the forms of large organic molecule-metal complexes were estimated from their concentrations as determined by the flow injection method.
Metals Mass spectrometry HPLC Simultaneous analysis