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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G. Schulze

Abbrev:
Schulze, G.
Other Names:
Address:
Institut für Anorganische und Analytische Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany
Phone:
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Fax:
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Email:

Citations 13

"Flow Injection Potentiometric Stripping Analysis And Potentiometric Stripping Coulometry. Micro-analytical Methods For Heavy Metals"
Microchim. Acta 1984 Volume 82, Issue 3-4 Pages 191-201
G. Schulze, M. Husch and W. Frenzel

Abstract: The analysis, with a wall-jet (Metrohm EA-1096) or porous-carbon (prep. described) working electrode, has been successfully applied to the determination of Zn, Cd and Pb, rectilinear responses being obtained in the range 100 ng to 2.5 µg. A vitreous-carbon counter-electrode and a silver - AgCl reference electrode are used. With a 250 µL sample and a flow rate of 0.5 mL min-1, the limit of detection is 50 µg l-1. A new concept of potentiometric stripping coulometry depends on the use of Faraday's law to calculate the mass of deposited metal from the stripping time. When applied to the determination of 130 ng of Pb, a value of 133 ng was obtained.
Cadmium Lead Zinc Coulometry Potentiometric stripping analysis Electrode Electrode

"A New Concept For The Quasi Non-destructive Microsampling Of Historical Glasses"
Fresenius J. Anal. Chem. 1997 Volume 358, Issue 6 Pages 694-698
G. Schulze, I. Horn, H. Bronk

Abstract: A glass object was sampled by filing with a diamond-coated Cr file. For the determination of Si, the file was sonicated for 20 min in 5 mL 6% Na2CO3/K2CO3 (1:1) to remove the sample material, and was also washed with water. The slurry and washings were combined and evaporated to dryness, and then fused at 1000°C for 20 min. For other determinations, the file was immersed in 0.4 mL HF or HF/HClO4 (3:1), then rinsed with water. The combined solution and washings were evaporated to dryness and the residue was reconstituted prior to analysis. Digestion of the residue with Cl/H2O was used prior to the determination of Au. Si and P were determined by FIA with photometric detection (based on the molybdenum blue reaction). Other elements were determined by ion chromatography or GFAAS (details given).
Gold Silicon Phosphorus Commercial product Spectrophotometry Sample preparation Sample preparation

"Ion Exchange Micro Columns For Online Preconcentration Of Heavy Metals. 2. Online Break-through Test For Zinc, Cadmium And Lead"
Fresenius J. Anal. Chem. 1995 Volume 353, Issue 2 Pages 119-122
O. Elsholz, and G. Schulze

Abstract: An on-line break-through test for zinc, cadmium and lead has been carried out by means of a flow-through cell and computerized potentiometric stripping analysis. This test has been applied to seventeen ion-exchange materials and enabled within a short time a predecision about the suitability of a resin for a special precon-centration problem. For the determination of the three trace elements in drinking water five ion exchangers are found to be appropriate without restriction and eight resins with some restrictions (not suitable for all three elements, weak matrix influences).
Cadmium Lead Zinc Ion exchange Column Preconcentration

"Ion-exchange Micro Columns For On-line Preconcentration Of Heavy Metals I. A Rapid Voltammetric Screening Test Of Ion-exchange Kinetics"
Fresenius J. Anal. Chem. 1989 Volume 335, Issue 7 Pages 721-727
G. Schulze and O. Elsholz

Abstract: A screening test for the investigation of the kinetical behavior of ion-exchange materials is described. The test enables to decide within a short time which resin may be suitable for a special pre-concentration problem. It is based on voltammetric measurements carried out in a single vessel. Using Zn, Cd, Pb and Cu, seventeen ion-exchange materials were checked. Experimental conditions including pH, quantity and particle size of the resins were studied. With regard to water analysis the influence of Na, Ca, Mg, Zn and Fe was investigated. For the determination of the four trace elements in drinking water eight ion exchangers proved to be recommendable at pH 8.

"Investigations On The Equivalence Of Analytical Procedures - Determination Of Chloride By Flow Injection Analysis And DIN Method In Water Analysis"
Fresenius J. Anal. Chem. 1989 Volume 334, Issue 1 Pages 9-12
G. Schulze, O. Elsholz, R. Hielscher, A. Rauth, S. Recknagel und A. Thiele

Abstract: Water was de-gassed and analyzed by one of the following methods. (i) A portion is injected into a stream of water, then mixed with a 15% methanolic solution of 2 mM Hg(SCN)2, 80 mM Fe(NO3)3 and 50 mM HNO3 and the absorbance is measured at 463 nm. (ii) A portion is injected into a stream of water, then mixed with 0.7 M Na acetate followed by 0.1 M Na acetate containing 1 mg mL-1 of Cl-. Detection is by means of tubular silver flow-through electrodes. (iii) A portion is injected into a stream of 2 M HNO3, this is mixed with a solution of 100 mg L-1 of AgNO3, the ppt. is filtered off and the filtrate is analyzed by AAS at 328.1 nm. The results obtained were reproducible and accurate and compared well with those obtained by the German standard (DIN) method. The methods developed were faster and more economic in the use of reagents than the standard method. For methods (i), (ii) and (iii), 120, 180 and 40 samples h-1, respectively, could be analyzed.
Chloride Environmental Water Waste Sludge Spectrophotometry Spectrophotometry Electrode Precipitation Filter Standard method

"Online Break-through Test For Ion-exchange Micro-columns Using Flow Injection Potentiometric Stripping Analysis"
Fresenius J. Anal. Chem. 1989 Volume 333, Issue 7 Pages 740-740
G. Schulze and O. Elsholz

Abstract: UFL
Potentiometric stripping analysis Ion exchange

"Comparison Of Potentiometric Stripping Analysis And Anodic-stripping Voltammetry In Flow Injection Analysis. Interference In Determination Of Lead"
Fresenius J. Anal. Chem. 1989 Volume 332, Issue 8 Pages 844-848
Gerhard Schulze, Edzard Han und Wolfgang Frenzel

Abstract: The effects of some inorganic ions, organic anions and Triton X-100 (I) on such determinations of 1 to 10 mg L-1 of Pb(II) at a Hg-film electrode were studied. Portions of sample were injected into a carrier stream of 0.1 M HCl containing 20 mg L-1 of Hg(II) for potentiometric stripping analysis (PSA) or 0.1 M KNO3 containing 20 mg L-1 of Hg(II) for anodic-stripping voltammetry (ASV), and analyzed in a wall-jet flow cell containing a vitreous-carbon counter electrode and a Ag - AgCl reference electrode (procedures described). There was no interference from 1 M Cl-, -NO3- or -ClO4- or 10 mM SO42-, but I- interfered seriously. Interference from metals capable of forming an amalgam was avoided by using a deposition potential of -0.8 to -0.6 V. The tolerance limits for Cr, Fe, Ni and Co ranged from 0.02 M Fe to 1 M Ni and -Co. Up to 1 M acetate, -citrate or -tartrate or up to 0.01% of I did not affect the PSV results, but interfered with determinations by ASV. The effects of some inorganic ions, organic anions and Triton X-100 (I) on such determinations of 1 to 10 mg L-1 of Pb(II) at a Hg-film electrode were studied. Portions of sample were injected into a carrier stream of 0.1 M HCl containing 20 mg L-1 of Hg(II) for potentiometric stripping analysis (PSA) or 0.1 M KNO3 containing 20 mg L-1 of Hg(II) for anodic-stripping voltammetry (ASV), and analyzed in a wall-jet flow cell containing a vitreous-carbon counter electrode and a Ag - AgCl reference electrode (procedures described). There was no interference from 1 M Cl-, -NO3- or -ClO4- or 10 mM SO42-, but I- interfered seriously. Interference from metals capable of forming an amalgam was avoided by using a deposition potential of -0.8 to -0.6 V. The tolerance limits for Cr, Fe, Ni and Co ranged from 0.02 M Fe to 1 M Ni and -Co. Up to 1 M acetate, -citrate or -tartrate or up to 0.01% of I did not affect the PSV results, but interfered with determinations by ASV.
Lead Potentiometric stripping analysis Voltammetry Interferences Triton X Surfactant

"Dual Detection For Optimization Of Gas Diffusion In Flow Injection Analysis. Determination Of Ammonium And Sulfide"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 714-717
G. Schulze Contact Information, M. Brodowski, O. Elsholz und A. Thiele

Abstract: Flow diagrams are given for the flow injection determination of sulfide (as H2S) and ammonium (as NH3), with use of a gas-permeable membrane for analyte transfer from donor to acceptor stream. The efficiency of this transfer has been studied. For H2S, a retardation loop was used to connect the donor stream to the 644-nm detector for parallel monitoring of both streams; the efficiency was 30 to 40%. For NH3, two parallel gas diffusion unit - 578-nm detector systems were used; the efficiency was ~7%. At 80°C, the efficiency increased by factors of 1.2 and 1.8, respectively, over that at ambient temperature Two PTFE materials are recommended for membrane construction.
Ammonium Sulfide Spectrophotometry Gas diffusion Heated reaction Multidetection Optimization Tecator Teflon membrane

"Investigations On The Equivalence Of Analytical Procedures - Flow Injection Analysis And DIN Method In The Determination Of Orthophosphate In Surface Water"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 711-713
G. Schulze Contact Information und A. Thiele

Abstract: Sample solution is injected into a carrier stream (H2O, 2.0 mL min-1), mixed with 1% (NH4)6Mo7O24.4H2O solution in 0.6 M H2SO4 (0.8 mL min-1) and further mixed with 0.2% hydrazinium sulfate in 0.5 M H2SO4 (0.6 mL min-1). Detection of molybdenum blue is at 690 nm. Calibration of the procedure is discussed. Results obtained for six water samples by this method and by the DIN method show total similarity for only one sample; for the others the results are equivocal.
Phosphate Surface Spectrophotometry Method comparison Standard method Tecator

"Dual-detection For Optimization Of Gas Diffusion In Flow Injection Analysis. Determination Of Ammonium And Sulfide"
Fresenius J. Anal. Chem. 1987 Volume 329, Issue 6 Pages 714-717
G. Schulze, M. Brodowski, O. Elsholz und A. Thiele

Abstract: Using gas diffusion, ammonium and sulfide can be determined selectively by flow injection analysis. An estimation of the membrane transference is achieved by dual-detection. It permits the determination of the volatile component in both the donor and the acceptor stream. This is performed by use of a retardation loop in the case of sulfide. For ammonium, two gas diffusion units are coupled with each other. As a measure of the membrane transference the effectivity of transfer is defined, estimating 30-40% for hydrogen sulfide and ~7% for ammonia. An elevation of temperature to 80°C increases the membrane transference by a factor of 1.2 and 1.8, respectively. Different membranes were tested.
Ammonium Sulfide Detector Gas diffusion Multidetection Optimization

"Matrix Exchange Techniques For The Simultaneous Determination Of Several Elements In Flow Injection Potentiometric Stripping Analysis"
Fresenius J. Anal. Chem. 1985 Volume 322, Issue 3 Pages 255-260
G. Schulze, W. Bönigk and W. Frenzel

Abstract: The determination of Pb, Sn, Cd and Tl in their binary, ternary and quaternary mixtures in the 1 to 10 mg L-1 range is described, with use of a Tecator Striptec measuring system with a flow injection analysis-Star unit and electrochemical detection at -1 V with a vitreous-carbon electrode; the mobile phase (1.6 mL min-1) was 0.01 M HCl containing 40 mg L-1 of Hg(II). Samples containing 50 mg L-1 of Hg(II) were injected, with deposition times of 20 to 60 s and a stripping time of 12.4 s. The optimum electrolyte was aqueous 5 M NH3 - 0.5 M KOH. The calibration graphs were rectilinear for the cited range.
Lead Tin Cadmium Thallium Electrode Potentiometric stripping analysis Simultaneous analysis Tecator

"Different Approaches To The Determination Of Ammonium Ions At Low Levels By Flow Injection Analysis"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 121-136
G. Schulze, C. Y. Liu, M. Brodowski and O. Elsholz, W. Frenzel, J. Möller

Abstract: For determination of 1 µM-NH3 by flow injection analysis, an optimized gas diffusion system was used, with spectrophotometric or selective-electrode detection. The gas diffusion unit had channels 7.5 cm long, 2 mm wide and 0.2 mm deep. The spectrophotometric detection flow cell had 10 mm pathlength and a capacity of 8 or 18 µL. The selective electrode (0.7 mm diameter, surface area ~20 mm2) consisted of nonactin in PVC and was used with an Orion 90-02 double-junction reference electrode. Spectrophotometric detection with bromocresol purple provided a lower limit of 0.2 µM, but was subject to background interference from, e.g., CO2. The selective electrode provided Nernstian response for 1 to 100 µM, with a detection limit of ~0.1 µM.
Ammonium Potentiometry Spectrophotometry Electrode Gas diffusion Interferences Merging zones Optimization Preconcentration Review Tecator

"Flow Cell With Flexible Deposition Efficiency For A Dual-detection System Based On Potentiometric Stripping Analysis And Atomic Absorption Spectrometry"
Anal. Chim. Acta 1987 Volume 196, Issue 1 Pages 153-161
G. Schulze, M. Koschany and O. Elscholz

Abstract: The cited flow cell is described in detail. The flow pattern, measurement of dispersion and deposition efficiency are discussed. Two types of dual detection are possible. If the sample concentration. is lower than the detection limit of flame AAS, a porous carbon felt electrode is inserted into the cell to collect the analyte ions for both potentiometric stripping analysis and pre-concentration. for AAS. If the concentration. of the sample is suitable for flame AAS, a vitreous-carbon electrode is used and two independent signals are obtained. The deposition efficiency can be altered from 1 or 2% (vitreous carbon) to 24% (carbon felt). In the determination of Pb in drinking water, pre-concentration. on carbon felt increased the sensitivity for flame AAS by one order of magnitude. This enabled determination of Pb in the µg L-1 range by flame AAS. A 1.5 mL injection required an electrolysis time of 60 s.
Lead Water Electrode Electrode Potentiometric stripping analysis Spectrophotometry Dispersion Flowcell Multidetection