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

European Journal of Pharmaceutical Sciences

  • Publisher: Elsevier
  • FAD Code: EJPS
  • CODEN: EPSCED
  • ISSN: 0928-0987
  • Abbreviation: Eur. J. Pharm. Sci.
  • DOI Prefix: 10.1016/j.ejps,10.1016/S0928-0987
  • Language: English
  • Comments: Fulltext from 1993 V1

Citations 4

"Determination Of Piroxicam By Solid-phase Spectrophotometry In A Continuous Flow System"
Eur. J. Pharm. Sci. 2002 Volume 15, Issue 2 Pages 179-183
María Isabel Pascual-Reguera, María Jose Ayora-Cañada and María Soledad Castro Ruiz

Abstract: A simple flow injection UV spectrophotometric method was developed for the determination of piroxicam. The method is based on its transient retention and concentration on Sephadex DEAE-A-25 anion-exchange gel beads packed in the flow cell and the continuous monitoring of its native absorbance on the solid phase at 354 nm. The sample was injected into a 0.1 M NaCl carrier stream at pH 9.5 by using a simple monochannel FIA manifold. When the analytical signal reached a maximum value, piroxicam was eluted from the solid support by means of a desorbing solution (0.2 M, pH 4.5). The response of the sensor was linear in the concentration range 0.5 -10 µg mL-1 with a RSD (%) of 1.8, a detection limit (3s, criterion) of 0.1 µg mL-1 and a sampling rate of 13 h-1. Application to the analysis of pharmaceutical samples testifies to the utility of this sensor. The accuracy of the proposed method was better than 5%. (C) 2002 Elsevier Science B.V. All rights reserved.

"A Flow-through Optosensing Device With Fluorimetric Transduction For Rapid And Sensitive Determination Of Dipyridamole In Pharmaceuticals And Human Plasma"
Eur. J. Pharm. Sci. 2001 Volume 13, Issue 4 Pages 385-391
A. Ruiz-Medina, M. L. Fernández-de Córdova and A. Molina-Díaz

Abstract: A flow-through optosensor with fluorimetric transduction has been prepared for the sensitive and selective determination of dipyridamole in aqueous solutions and biological fluids. The method is based on a monochannel flow injection analysis system using Sephadex QAE A-25 resin, placed into a Hellma 176-QS fluorimetric flow-through cell, as an active sorbing substrate. The native fluorescence of dipyridamole fixed on the solid sorbent is continuously monitored at wavelengths of 305 and 490 nm for excitation and emission, respectively. After obtaining the maximum fluorescence intensity, the eluent solution (KH2PO4/NaOH buffer solution, c(T)=0.05 mol 1-1, pH 6.0) is allowed to reach the flow cell, the analyte is removed, and the resin support is regenerated. When an NaOH (10^-4 mol 1-1)/NaCl (0.1 mol 1-1) solution is used as carrier solution, at a flow-rate of 1.56 mi min-1, the sensor responds linearly in the measuring range of 10^-500 µ-g L-1 with a detection limit of 0.94 µg L-1 and a throughput of 22 samples per hour (300 µL of sample volume). The relative standard deviation for ten independent determinations (200 µg 1-1) is less than 0.82%. The method was satisfactorily applied to the determination of dipyridamole in pharmaceutical preparations and human plasma. (C) 2001 Elsevier Science B.V. All rights reserved.

"Evaluation Of A Novel High-throughput Assay For Cytochrome P450 2D6 Using 7-methoxy-4-(aminomethyl)-coumarin"
Eur. J. Pharm. Sci. 2000 Volume 12, Issue 2 Pages 151-158
Jennifer Venhorst, Rob C. A. Onderwater, John H. N. Meerman, Nico P. E. Vermeulen and Jan N. M. Commandeur

Abstract: We recently reported on the design, synthesis and characterisation of a novel and selective substrate of human cytochrome P450 2D6 (CYP2D6), 7-methoxy-4-(aminomethyl)-coumarin (MAMC). Here, we describe a high-throughput microplate reader assay, which makes use of MAMC as a fluorescent probe for determining the inhibition and activity of CYP2D6 in heterologously expressed systems and human liver microsomes,The high-throughput screening (MTS) assay can be used both in an end-point and real-time configuration, and is easy to use, rapid and sensitive. In addition, end-point measurements by means of how injection analysis have also successfully been performed. The MTS-assay was validated by performing inhibition experiments for several low- and high-affinity ligands (n = 6) of CYP2D6, and comparing the findings to those obtained with the standard O-demethylation assay of dextromethorphan. The results indicate that all compounds tested display competitive inhibition in both the MAMC and dextromethorphan assay, and the Ki values reveal a very good correlation (R-2 = 0.984) between the two assays. To further demonstrate the usefulness of the MTS-assay, IC,, values of a series of five N-substituted analogs of 3,4-methylenedioxyamphetamine for CYP2D6 have been determined. The results obtained demonstrate that the current MTS-assay represents a significant improvement over previous assays, with a higher turnover of MAMC and a higher selectivity for CYP2D6.

"Spectrophotometric Methods For Determining Meloxicam In Pharmaceuticals Using Batch And Flow Injection Procedures"
Eur. J. Pharm. Sci. 2000 Volume 9, Issue 3 Pages 311-316
M. Soledad García, Concepción Sánchez-Pedreño, M. Isabel Albero and José Martí

Abstract: Two sensitive and fast spectrophotometric methods using batch and flow injection procedures for the determination of meloxicam (MX) are proposed. The methods are based on the formation of a green complex between this drug and Fe(III) [2MX/Fe(III)] in a methanolic medium. The calibration graphs resulting from measuring the absorbance at 570 nm are linear over the ranges 2.0-200 and 5.00-250 mg L-1 with detection limits of 0.47 and 0.72 mg L-1, respectively. Furthermore, a flow injection spectrophotometric method involving measurement of the absorbance of the drug at 362 nm in 0.1 M NaOH is presented. The calibration graph is linear over the range 0.5-20 mg L-1 with a detection limit of 0.04 mg L-1. The methods are applied to the routine analysis of MX in pharmaceuticals.