University of North Florida
Browse the Citations
-OR-

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

View Stuart Chalk's profile on LinkedIn

Janusz Pawliszyn

Abbrev:
Pawliszyn, J.
Other Names:
Address:
Department of Chemistry, University of Waterloo, Waterloo ON, Canada
Phone:
+1-519-8851211
Fax:
+1-519-7460435

Citations 7

"Determination Of Stimulants In Human Urine And Hair Samples By Polypyrrole Coated Capillary In-tube Solid Phase Microextraction Coupled With Liquid Chromatography-electrospray Mass Spectrometry"
Talanta 2001 Volume 54, Issue 4 Pages 655-672
Jingcun Wu, Heather Lord and Janusz Pawliszyn

Abstract: A simple and sensitive method for the determination of amphetamine. methamphetamine and their methylenedioxy derivatives in urine and hair samples was developed by coupling automated in-tube solid phase microextraction (SPME) to high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ES-MS). To achieve optimum performance, the conditions for both the in-tube SPME and the ES-MS detection were investigated. ES-MS detection conditions were studied by flow injection analysis (FIA) with direct liquid injection. In-tube SPME conditions were optimized by selecting the appropriate extraction parameters. including capillary stationary phases and sample pH. For the compounds studied, a custom-made polypyrrole (PPY) coated capillary showed superior extraction efficiency as compared to commercial capillaries. Therefore. the PPY coated capillary was selected for in-tube SPME in this study. The calibration curves of stimulants were linear in the range from 0.1 to 100 ng mL (1) with detection limits (S/N = 3) of 8-56 ng L-1. This method was successfully applied to the analysis of the stimulants: in spiked human urine and hair samples. (C) 2001 Elsevier Science B.V. All rights reserved.
Extraction

"Determination Of Tributyltin By Automated In-tube Solid-phase Microextraction Coupled With HPLC-ES-MS"
J. Anal. At. Spectrom. 2001 Volume 16, Issue 2 Pages 159-165
Jingcun Wu, Zoltán Mester and Janusz Pawliszyn

Abstract: A simple and sensitive method has been developed for the determination of tributyltin (TBT) in aqueous samples and environmental samples. Automated in-tube solid-phase microextraction (SPME) and high-performance liquid chromatography (HPLC) were coupled to a quadrupole mass spectrometer (MS) using electrospray (ES) as an ionization source. To achieve optimum performance, the conditions for both in-tube SPME and ES-MS detection were optimized for the analysis of TBT. A commercially available capillary, Supel-Q PLOT, showed the best extraction efficiency for TBT and, therefore, it was selected for in-tube SPME. The in-tube SPME-HPLC-ES-MS method provided a linear relationship between the analyte concentration and signal intensity in the range of 0.5-200 ng mL-1 TBT, with a detection limit of 0.05 ng mL-1. The method performance was evaluated by determining the content of TBT in a sediment reference material (PACS-2).

"Electrochemically Controlled Solid-phase Microextraction Based On Conductive Polypyrrole Films"
Anal. Chem. 2002 Volume 74, Issue 18 Pages 4855-4859
Jingcun Wu, W. M. Mullett, and Janusz Pawliszyn

Abstract: Solid-phase microextraction (SPME) fiber coatings based on conductive polypyrrole films were prepared for the electrochemical extraction and desorption of ionic analytes. Simple preparation of each of the PPY extraction coatings on a platinum wire was possible with a constant potential method, but more importantly, cycling of the film between oxidation and reduction potentials facilitated the extraction and desorption of ionic analytes. The analytes were desorbed into a sample aliquot of water and were determined by flow injection analysis using a mass spectrometer. The fiber coatings and the developed electrochemical SPME method were found to be stable and reproducible (RSD < 5%; N = 5) and could be extended to several cations and anions, confirming the versatility of the approach. Preconcentration of the analyte on the fiber was also possible by repeating the processes to increase the amount of analyte extracted.
Resin

"Nanoliter Volume Sequential Differential Concentration Gradient Detector"
Anal. Chem. 1988 Volume 60, Issue 24 Pages 2796-2801
Janusz Pawliszyn

Abstract: A simple optical detection system is described and illustrated that has a detection volume of 2 nl. It comprises a He - Ne laser, means of generating two focused beams propagating close to each other, and a single photodiode sensor. The output signal from the sensor is proportional to concentration. over four orders of magnitude, and the refractive-index gradient detection limit is 2 x 10 -4 refractive index unit m-1 (equivalent to 0.7 µm-sucrose). The system has been applied in flow injection analysis and capillary zone electrophoresis.
Electrophoresis Spectrophotometry Apparatus Laser Refractive index Photodiode

"Detection Of Flowing Samples With A Selective Concentration Gradient Method"
Anal. Chem. 1988 Volume 60, Issue 8 Pages 766-773
Janusz Pawliszyn

Abstract: Refractive-index gradients were generated in a flowing medium, and were measured by means of a single probe beam (Schlieren optics) passing through a flow cell constructed from a fused-silica capillary tube (50 µm i.d.) or an open-tubular column (25 µm i.d.) leading into a tube of square (200 µm) internal cross-section. The excitation beam from a He - Ne laser and a probe beam from a light-emitting diode were supplied to the cell via optical fibers. The thermal relaxation of the system after an excitation pulse was studied by measurement of the transient signal, which was related to the solute concentration. The detection limit was 1 fmol, but depended on the volume of the detector cell.
Spectrophotometry Laser Light emitting diode Gradient technique Optical fiber Refractive index

"Properties And Applications Of The Concentration Gradient Sensor To Detection Of Flowing Samples"
Anal. Chem. 1986 Volume 58, Issue 14 Pages 3207-3215
Janusz Pawliszyn

Abstract: An optical sensor is described for the monitoring of concentration. gradient by measurement of the refractive-index gradient with use of a non-absorbed light beam as probe in the detector volume. Light-beam deflection measurement (Schlieren optics) has been used to monitor analyte concentration. in flowing streams. For sucrose the rectilinear dynamic range extends from 5 µM to around 0.1M. The sensor can differentiate between sharp and broad peaks, and peak broadening can be avoided by the sheath-flow method. Response is rectilinear in the non-selective mode. The detector was tested alongside a standard refractive-index detector (Waters R400) and its applicability in flow injection analysis and HPLC systems is demonstrated.
HPLC Refractometry Sensor Apparatus Detector Gradient technique

"Online Monitoring Of Flowing Samples Using Solid-phase Micro-extraction Gas Chromatography"
Anal. Chim. Acta 1993 Volume 284, Issue 2 Pages 265-273
Safa Motlagh and Janusz Pawliszyn*

Abstract: The solid-phase micro-extraction (SPME) device was constructed by replacing the metal wire plunger assembly of a Hamilton 7105-N syringe with a poly(dimethylsiloxane)-coated fiber (6 cm x 253 µm o.d.) with a silica core (141 µm o.d.) partially inserted into a 30 gauge, 15 cm-long stainless-steel sheath. The SPME was supported in a solution of toluene (0.1 ppm) which was agitated by magnetic mixing, intrusive mixing or sonication (details given). After the extraction period, the SPME fiber was inserted into the injector of a Varian 6000 gas chromatograph for analysis of the adsorbed material on a SPB-1 column (15 m x 0.53 mm i.d.; 0.5 µm) operated with temperature programming from 0-211°C (held for 1.25 min) at 25°C/min, He as carrier gas (4.2 ml/min) and FID. Cryogenic focusing was used to cool the column below room temperature to trap the volatiles in a narrow band at the head of the column. Sonication was the most efficient and convenient agitation method (toluene equilibrated in 1 min) and was applied to continuous-flow (16 ml/min) experiments (details given); magnetic stirring was not efficient and intrusive mixing caused sample heating. The method allows GC to be incorporated into a FIA system.
GC Sample preparation Solid phase extraction Interface