University of North Florida
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Contact Info

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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Joel M. Harris

Abbrev:
Harris, J.M.
Other Names:
Address:
Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
Phone:
(801) 581-3585
Fax:
NA

Citations 6

"In Situ Fluorescence Studies Of Aluminum Ion Complexation By 8-hydroxyquinoline Covalently Bound To Silica"
Anal. Chem. 1989 Volume 61, Issue 9 Pages 1001-1010
M. R. Weaver and J. M. Harris

Abstract: Investigation of interfacial effects on an immobilized reagent response was undertaken by using in situ fluorescence spectroscopy and flow Injection methods. A procedure to immobilize 8-hydroxyquinoline by an alkyl siloxane linkage to silica gel was used to produce a chemically stable material, capable of producing fluorescent complexes with a number of metal ions. Reactions of this reagent with aluminum ion were studied by using flow injection methods to control the solution conditions and the exposure of the reagent to metal ion samples, providing some insight into the chemical interactions that affect the equilibrium behavior. Surface equilibrium constants were calculated and compared to the free solution values for the aluminum quinolate complex. Differences in the behavior of the free solution and immobilized reagent under flow injection and steady-state conditions could be related to changes In the surface potential of the silica gel. The pH and Ionic strength dependence of the reaction and saturation of the immobilized ligand response further point out the important role that the double-layer potential plays in the reactivity of surface bound reagents for lonic species.
Aluminum Fluorescence Complexation Alumina 8-Hydroxyquinoline

"Double-beam Thermal Lens Spectrometry"
Anal. Chem. 1985 Volume 57, Issue 13 Pages 2434-2436
K. L. Jansen and J. M. Harris

Abstract: The construction of a double-beam configuration for thermal-lens absorption measurements is reported, in which a single laser beam is split into two, only one beam being passed through the sample. Continuous modulation and lock-in amplification of the signal produced by subtraction of the beam intensities allow application of the system to real-time monitoring, such as flow injection analysis or HPLC. Double-beam thermal-lens detection was evaluated for the flow injection analysis of trace levels of iodine in CCl4.
Iodine Organic compound Spectrometry Apparatus Detector Organic phase detection

"Thermal Lens Absorption Measurements By Flow Injection Into Supercritical Fluid Solvents"
Anal. Chem. 1984 Volume 56, Issue 14 Pages 2801-2805
R. A. Leach and J. M. Harris

Abstract: The flow system consists of a reservoir of the supercritical fluid (CO2 near its critical point) that is used to fill a high-pressure syringe pump. The fluid is filtered and passed through a reversed-phase ODS chromatographic column (to remove the solvent for the analyte) to a flow cell and back-pressure regulator. The sample (a solution of azulene in hexane) is injected, via a valve, into the flowing supercritical fluid. Detection is by means of a thermal-lens absorption instrument, based on the Kr-ion laser previously described (cf. Anal. Abstr., 1985, 47, 4J100). Use of this technique enhances the sensitivity for azulene (relative to CCl4). Background absorption is low and permits low detection limits.
Azulene Spectrometry Supercritical fluid

"Thermal-lens Absorption Measurements On Small-volume Samples"
Anal. Chem. 1984 Volume 56, Issue 6 Pages 922-925
C. A. Carter and J. M. Harris

Abstract: Good sensitivity and the use of focused laser excitation make thermal-lens calorimetry particularly suitable for detection in small-volume samples, as required in HPLC and flow injection analysis. The fundamental balance between detection volume and sensitivity is shown to be related to the divergence of the focused beam. An expression is derived for minimum sample volume for a given pathlength. Consideration is given to the sources of noise that depend directly on how tightly the laser is focused through the sample. A 300-mW argon-ion laser at 514.5 nm is applied to test solution of iodine in CCl4 in cells of pathlength 1 mm (volume <0.5 µL) and 1 cm. Sample concentration. ranged from 2.5 nM to 2.5 µM for the larger volume and from 25 nM to 25 µM for the smaller volume Limits of detection of 3.7 pg and 0.18 pg for the larger and smaller volume, respectively, are reported.
Iodine Calorimetry Laser

"Flow Injection Of Ultra Trace Level Samples Into Laser-based Detectors"
Anal. Chem. 1982 Volume 54, Issue 13 Pages 2337-2340
J. M. Harris

Abstract: Application of lasers to the detection of ultratrace level species is presently hindered by traditional methods of sample manipulation. Flow Injection analysis (FIA) developed originally to automate routine determinations appears to have several attributes which would be beneficial In presenting samples to laser detectors. These attributes include small volume sampling, low risk of contamination, and large dynamic range for a given expenditure of time and reagents. Laser-induced fluorescence is used in this work to assess the merits of flaw injection for handling ultratrace level samples. The trade-off between sample throughput and dynamic range Is investigated, and the results are treated by using the theory of sample dispersion.
Fluorescence Detector Laser Ultratrace

"Real-time Thermal Lens Absorption Measurements With Application To Flow Injection Systems"
Anal. Chim. Acta 1984 Volume 164, Issue 1 Pages 91-101
R. A. Leach and J. M. Harris

Abstract: The thermal-lens apparatus described previously (cf. Dovichi and Harris, Anal. Abstr., 1981, 41, 2J111) was used in conjunction with a microcomputer for real-time data processing. A 1-cm fused-silica flow-cell (1 mm deep) was used in which the carrier stream flowed vertically upwards, thereby minimizing problems due to convection. In the determination of Fe with 1,10-phenanthroline in aqueous methanol (1:1), the limit of detection was 37 pg in a 100 µL sample, while in the determination of azulene and C. I. Solvent Green 3 in CCl4 solution, respective absorbance detection limits of 8.5 x 10^-7 and 14 x 10^-7 were possible. The use of the flow injection procedure was found to minimize problems of photochemical instability frequently encountered in static thermal-lens measurements.
Iron Azulene Solvent Green 3 Spectrometry PPB