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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Charles A. Lucy

Abbrev:
Lucy, C.A.
Other Names:
Address:
Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
Phone:
+1-780-492-0315
Fax:
+1-780-492-6742

Citations 11

"Determination Of Surfactant Concentration Using Micellar Enhanced Fluorescence And Flow Injection Titration"
Talanta 2000 Volume 50, Issue 6 Pages 1283-1289
Charles A. Lucy and Josephine S. W. Tsang

Abstract: Flow injection titration was used for the determination of anionic, cationic, nonionic and zwitterionic surfactants. The procedure was based on the micellar-enhanced fluorescence of 1,8-anilino-naphthalene sulfonate (ANS). Samples were injected into a carrier stream of phosphate buffer and 1.0 mol 1 (-) (1) NaCl. The sample then passed through a mixing chamber which generated the exponential peak shape needed for the titration as well as diluted the sample in the carrier stream to control the pH and ionic strength of the sample. The peak width was linearly related to the logarithm of the surfactant concentration. The minimum detectable concentration was governed by the critical micelle concentration for anionic, zwitterionic and nonionic surfactants, but below the critical micelle concentration for cationic surfactants. The linear range extended for similar to 1.5 orders of magnitude. Reproducibility ranged from 12% at the lower end of the calibration range to 1.1% at higher concentrations. For SDS recoveries of 82-108% were achieved in matrices as concentrated as 1 mol 1 (- 1) in NaCl or Na2SO4.
Surfactants, anionic Surfactants, cationic Surfactants, zwitterionic Fluorescence Micelle Surfactant Titrations Gradient technique Mixing chamber Phase separator

"Selectivity Enhancements For The Determination Of Thorium By Flow Injection Analysis Through The Formation Of The Thorium-DTPA HQS Fluorescent Ternary Complex"
Talanta 1996 Volume 43, Issue 6 Pages 811-817
Ye Liwena and Charles A. Lucya,*

Abstract: Sample was injected into a carrier stream (1 ml/min) of water and was merged with a reagent steam (0.3 ml/min) of 8-hydroxyquinoline-5-sulfonic acid (HQS) containing diethylenetriaminepenta-acetic acid (DTPA) in 2-amino-2-methyl-1-propanol (I). The resulting stream passed through a spiraled reaction coil (510 cm x 0.5 mm i.d.) and to a fluorimetric detector for detection at 500 nm (excitation at 360 nm). The pH and concentration of the reagent stream was optimized giving optimum conditions of 1 mM HQS and 5 mM DTPA in 100 mM I of pH 11. Calibration graphs were linear for 0.05-10 µM-Th(IV) with a detection limit of 12 ng/ml. Interferences from other metal ions are tabulated and discussed. The presences of transition metals and lanthanides do not interfere with Th determination.
Thorium-232 Fluorescence Interferences 8-hydroxyquinoline-5-sulfonic acid

"Achieving Rapid Low-pressure Ion Chromatography Separations On Short Silica-based Monolithic Columns"
J. Chromatogr. A 2006 Volume 1118, Issue 1 Pages 12-18
Sarah Pelletier and Charles A. Lucy

Abstract: Short silica-based monolithic columns (0.5-1 cm) are coated with the surfactant didodecyldimethylammonium bromide (DDAB) and used for fast ion exchange separations of small inorganic anions. Sources of extra-column band broadening are assessed and minimized to obtain separations of seven analytes (iodate, chloride, nitrate, bromide, nitrite, phosphate, sulphate) in two minutes at 2 mL/min. Eluents used are 6 and 9 mM 4-cyanophenol at pH 7.3-7.4 or 5 mM 4-hydroxybenzoic acid at pH 5.6. DDAB coating stability is improved by 15-fold by the addition of a DDAB coated pre-column before the injection valve. Separations are obtained using a low-pressure glass syringe.

"Ultra-rapid Analysis Of Nitrate And Nitrite By Capillary Electrophoresis"
J. Chromatogr. A 2000 Volume 884, Issue 1-2 Pages 311-316
Jeremy E. Melanson and Charles A. Lucy

Abstract: Rapid analysis of nitrate and nitrite by capillary electrophoresis (CE) has been limited by the ions very similar electrophoretic mobilities. With a pK(a) of 3.15, the mobility of nitrite can be selectively reduced using a low pH buffer in CE. A much shorter capillary can be used and separation voltages can be increased. With this method, nitrate and nitrite are separated in just over 10 s, This is roughly 20 times faster than current separation methods. Direct UV detection at 214 nm was employed and offered sub µM detection limits. Total analysis time (pre-rinse, injection, and separation) was less than 1 min, making this method ideal for high-throughput analysis.
Electroosmotic flow

"Modification Of 4-(2-pyridylazo)-resorcinol Post-column Reagent Selectivity Through Competitive Equilibria With Chelating Ligands"
J. Chromatogr. A 1997 Volume 770, Issue 1-2 Pages 69-74
Anne C. Co, Angela N. Ko, Liwen Ye and Charles A. Lucy*

Abstract: Aminopolycarboxylate ligands were added to the 4-(2-pyridylazo)-resorcinol (PAR) post-column reagent to alter the reagent selectivity towards transition metals. Addition of ethylenediaminetetraacetic acid (EDTA) completely suppressed the reaction between PAR and the metal ions. Addition of 0.1 mM nitrilotriacetic acid (NTA) to 1 mM PAR lowered the response to specific transition metal ions, but completely suppressed the PAR response to the lanthanides. Increasing the NTA concentration to 8 mM resulted in complete suppression of the PAR response to all metal ions except Cu2+ and Co2+, for which the detection limits were 3 and 1 ng, respectively. The observed selectivity results from the slow rate of conversion of metal ions from the M(NTA)(2)(4-) form to M(PAR)(2). 21 References
Metals, transition Magnesium Calcium Copper(II) Cobalt(II) HPIC Spectrophotometry Post-column derivatization Complexation Chelation

"Displacement Post-column Detection Reagents Based On The Fluorescent Magnesium 8-hydroxyquinoline-5-sulfonic Acid Complex"
J. Chromatogr. A 1994 Volume 671, Issue 1-2 Pages 121-129
Charles A. Lucy* and Liwen Ye

Abstract: A non-specific reagent for the post-column detection of metal ions was obtained by displacement of Mg2+ from Mg(CDTA)2- and reaction of the liberated Mg2+ with 8-hydroxyquinoline-5-sulfonic acid (I) to form a fluorescent complex. The kinetics and equilibria of the reaction and the effects of sequential and simultaneous addition of Mg-CDTA and I are discussed. Most experiments were conducted using an HPLC system in the FIA mode, with detection at excitation and emission wavelengths of 360 and 500 nm, respectively. The optimum sensitivity was obtained at pH 8. For simultaneous addition of the reagents, alkaline earth metals gave a positive response, but there was no response for transition metals. Addition of Mg(CDTA)2- followed by I2- gave a positive response for Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Cu2+, Ni2+ and Co2+. The response for Mn2+ was linear for 25-2500 pmol.
Magnesium(II) Calcium(2+) Strontium(II) Barium(2+) Manganese(II) Copper(II) Nickel(II) Cobalt(II) HPLC Fluorescence Indirect Post-column derivatization Optimization pH 8-hydroxyquinoline-5-sulfonic acid

"Enhanced Detection Of Porphyrins By Capillary Electrophoresis-laser Induced Fluorescence"
Electrophoresis 2002 Volume 23, Issue 11 Pages 1689-1694
Jeremy E. Melanson, Charles A. Lucy

Abstract: A highly sensitive technique for the analysis of urinary porphyrins using capillary electrophoresis (CE) coupled with laser-induced fluorescence (LIF) detection is reported. Separation of mesoporphyrin IX, coproporphyrin, uroporphyrin and the penta-, hexa- and heptacarboxylic acid porphyrins was achieved in 11 min using a 10 mm 2-(N-cyclohexylamino)ethanesulfonic acid (CHES, pH 10) -75 mm sodium dodecyl sulfate (SDS) buffer. Migration time and peak area repeatability were less than 1 and 5% relative standard deviation (RSD), respectively. Limits of detection of 20 pm (2 x 10^-11 m) were achieved employing the recently introduced Nichia violet diode laser for excitation at 400 nm. This represents an enhancement in sensitivity of over two orders of magnitude compared to previous reports. This high sensitivity for urinary porphyrins was demonstrated through the quantification of coproporphyrin and uroporphyrin in urine samples after up to a 100-fold dilution.

"Flow Injection Preconcentration Using Differential Flow Velocities In Two-phase Segmented Flow"
Anal. Chem. 1995 Volume 67, Issue 17 Pages 3036-3041
Charles A. Lucy and Susan Varkey

Abstract: A pseudostationary phase of organic solvent was produced from the wetting of hydrophobic tubing by the solvent within the concurrent flow of two immiscible phases through narrow tubing. The phase retention differences in a hexanol/aqueous acetate buffer of pH 4 (4:1) segmented flow system were used to retard extracted o-nitrophenol as test analyte and then concentrate it with a single 20 µL injection of 0.1 M NaOH as eluting reagent. Detection was carried out at 247 nm. The effects of sample volume, extraction coil length, flow rate, phase ratio and tubing diameter on the pre-concentration factor were studied. A throughput of 30 samples/h and pre-concentration factors in excess of 50-fold were obtained using a 900 cm long, 1 mm i.d. coil and a flow rate of 1 ml/min. In this work, a pseudostationary phase of organic solvent replaces the microcolumn in flow injection pre-concentration. This pseudostationary phase results from the wetting of hydrophobic tubing by the organic solvent within the concurrent flow of two immiscible phases through narrow tubing. If this wetting film is sufficiently thick, a differential velocity between the aqueous and organic phases develops within the two-phase segmented flow. The effect of experimental parameters such as sample volume, flow rate, phase ratio, and tubing diameter on the pre-concentration factor are characterized. Using these procedures, pre-concentration factors in excess of 50-fold are obtained with a throughput of 30 samples/h. Copyright 1995, American Chemical Society.
o-Nitrophenol Spectrophotometry Sample preparation Organic phase detection Preconcentration Solvent extraction Supported liquid membrane

"Formation Of Lanthanide/aminopolycarboylate/8-hydroxyquinoline-5-sulfonate Ternary Complexes And Their Application In The Selective Determination Of Hexadentate Chelating Agents"
Anal. Chem. 1995 Volume 67, Issue 1 Pages 79-82
Charles A. Lucy and Liwen Ye

Abstract: Lutetium was determined by FIA with water as carrier, a post-column reagent containing 0.1 mM 8-hydroxyquinoline-5-sulfonic acid (HQS) and 0.1 mM CDTA in 0.03 M bicine buffer of pH 8, and fluorimetric detection at 500 nm (excitation at 360 nm). Lutetium and other lanthanides were separated by HPLC on a 5 µm Delta-Pak C18 column (15 cm x 3.9 mm i.d.) with 3 mM octane-1-sulfonic acid containing a gradient (0.025-0.15M) of 2-hydroxy-2-methylpropionic acid as mobile phase (1 ml/min) and 1 mM HQS/4 mM CDTA as post-column reagent. Peak areas were used for quantitation. The detection limit for Lu was 5 nM and response was linear up to 10 µM. The same column was used to separate N-(hydroxyethyl)ethylenediaminetriacetic acid, EDTA and CDTA, with an initial mobile phase (1 ml/min) of 8% methanol containing 3 mM tetrapropylammonium bromide to which 4 mM 2-hydroxy-2-methylpropionic acid (pH 5.3) was added after 2 min. Response was linear up to 10 µM and the detection limit was 10 nM. Results compared well with those of spectrophotometric detection.
Lutetium HPLC Fluorescence Post-column derivatization Method comparison Complexation 8-hydroxyquinoline-5-sulfonic acid Chelation

"Solvent Extraction-flow Injection Without Phase Separation Through The Use Of The Differential Flow Velocities Within The Segmented Flow"
Anal. Chem. 1994 Volume 66, Issue 14 Pages 2220-2225
Charles A. Lucy and Ken K.-C. Yeung

Abstract: A solvent extraction-flow injection manifold is described that does not require a phase separator or an on-tube detector and quantifies both extracted and unextracted components from a single injection. The sample was injected into an aqueous phase and a hexanol-water segmented flow was established in the extraction coil. The wetting film of the organic phase formed on the walls of the Teflon tubing reduced the linear velocity of the organic flow, and the differential flow velocities yielded a separation in time between the unextracted and extracted components. The segmented flow was merged with a methanol stream and entered a mixing coil for homogenization before passage through the flow cell of an absorbance detector for monitoring at 254 nm. Large aqueous-to-organic ratios, high flow rates and long extraction coils enhanced the resolution. The method was applied to the determination of the active components in motion sickness tablets, with a throughput of 12 samples/h and a precision of 2.5 and 4% for 8-chlorotheophylline and diphenhydramine, respectively.
8-Chlorotheophylline Diphenhydramine Pharmaceutical Spectrophotometry Sample preparation Phase separator Solvent extraction

"Kinetics And Equilibria Of The Zinc-EDTA-PAR Post-column Reaction Detection System For The Determination Of Alkaline-earth Metals"
Anal. Chem. 1994 Volume 66, Issue 6 Pages 793-797
Charles A. Lucy and Huyen N. Dinh

Abstract: Stopped- and continuous-flow analysis with monitoring at 540 nm was used to determine the rate kinetics and equilibria of 4-(2-pyridylazo)resorcinol (PAR) and Zn-EDTA-PAR complexation with metal standards in the presence of auxiliary agents such as ethylenediamine and NH3. The kinetics and sensitivity of the Zn-EDTA-PAR reagent were strongly dependent on the nature and concentration of the auxiliary complexing agent, which stabilized the PAR reagent and enhanced the reaction rate. Post-column reaction studies were performed on a column (15 cm x 3.9 mm i.d.) of Delta Pak C18 (5 µm), with 50 mM tartaric acid/1.2 M octanesulfonic acid of pH 3.4 as mobile phase. Ethylenediamine was more effective than NH3 for the determination of alkaline-earth metals, as it gave faster reaction kinetics and less inhibition of Zn(PAR)2 formation. The detection sensitivity of alkaline-earth metals increased with increasing ethylenediamine concentration up to a maximum at 40 mM and was a function of the competitive complexation by the auxiliary agent. The auxiliary agents suppressed the direct reaction of PAR with metal ions such as Zn2+, and should be used sparingly in post-column reagents.
Metals, alkaline earth Spectrophotometry Stopped-flow Post-column derivatization Kinetic Complexation Indirect