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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Acta Chimica Slovenica

  • Publisher:
  • FAD Code: ACHS
  • CODEN: ACSLE
  • ISSN: 1318-0207
  • Abbreviation: Acta Chim. Slov.
  • DOI Prefix: NA
  • Language: English,Slovak
  • Comments: Fulltext from 1954 V1

Citations 5

"Sub-second FFT Continuous Stripping Cyclic Voltammetric Technique As A Novel Method For Pico-level Monitoring Of Imipramine At Au Microelectrode In Flowing Solutions"
Acta Chim. Slov. 2006 Volume 53, Issue 4 Pages 499-505
Parviz Norouzi*, Mohammad Reza Ganjali, Behrouz Akbari-Adergani

Abstract: A novel method for the determination of imipramine in flow-injection systems has been developed. The method was used for the fast determination of imipramine in its pharmaceutical formulations and biological samples. The developed technique is very simple, precise, accurate, time saving and economic as compared to all previously reported methods. The effects of various parameters on the sensitivity of the method were investigated. The best performance was obtained with the conditions, pH value of 2.0, and sweep rate value of 60 V s-1, accumulation potential of 100 mV and accumulation time of 0.5s. In this work, we introduce a special computer based numerical method, for calculation of the analyte signal and noise reduction. The electrode response was calculated based on partial and total charge exchanges at the electrode surface after subtracting the background current from noise. The waveform potential consisting of potential steps for cleaning and accumulation of analyte, and potential ramp was applied on an Au disk microelectrode (with a radius of 12.5 ?m). The method was linear over the concentration range of 14-22400 pg mL-1 (r = 0.999) with a limit of detection and quantitation 4.55 and 14 pg mL-1, respectively. The method has the requisite accuracy, sensitivity, precision and selectivity to assay imipramine in tablets.

"Flow Injection Spectrophotometric System For N-acetyl-L-cysteine Determination In Pharmaceuticals"
Acta Chim. Slov. 2005 Volume 52, Issue 2 Pages 164-167
Ana Luiza de Toledo Fornazari, Willian Toito Suarez, Heberth Juliano Vieira, and Orlando Fatibello-Filho*

Abstract: A flow injection system with spectrophotometric detection is proposed for determining N-acetyl-L-cysteine in pharmaceutical formulations. In this system, N-acetyl-L-cysteine was oxidized by Fe(III) and the Fe(II) produced is spectrophotometrically monitored as Fe(II)-1,10-phenantroline complex at 510 nm. Under the optimum analytical conditions, the linearity of the calibration curve for N-acetyl-L-cysteine ranged from 3.5 x 10^-6 to 4.3 x 10^-4 M. The detection limit of 6.3 x 10^-7 M and recoveries between 98.5 to 110% were obtained.

"Automatic Spectrophotometric Procedure For Determination Of L-ascorbic Acid Based On Reduction Of Iron(III)-thiocyanate Complex"
Acta Chim. Slov. 2004 Volume 51, Issue 4 Pages 717-727
Meissam Noroozifar,* Mozhgan Khorasani-Motlagh, and Abdol-Rahim Farahmanda

Abstract: A very simple spectrophotometric method has been developed for indirect determination of L-ascorbic acid using flow injection system based on the redox reaction between iron(III)-thiocyanate complex and L-ascorbic acid in acidic medium. A negative peak results from an injection of L-ascorbic acid into an iron(III)-thiocyanate complex camer stream when absorbance is monitored at 462 nm. The height of the negative peak is proportional to the concentration of L-ascorbic acid in the sample. Figures of merit such as a relative standard deviation of 2.0% (n=6), linearity range up to 100 ?g/mL and detection limit of 0.36 ?g/mL were obtained. No significant differences at the 95% confidence level were observed in comparison with results obtained by a manual procedure. The proposed system allowed the determination of L-ascorbic acid in pharmaceutical formulations and foods.

"Determination Of Molybdenum By Flow-injection Analysis"
Acta Chim. Slov. 2003 Volume 50, Issue 4 Pages 799-806
Salem A. Barakat,* Tariq Y. Mahmoud

Abstract: A spectrophotometric flow injection method for the determination of molybdenum in a variety of samples based on the thiocyanate complex formation is proposed. Effects of Cu(II), acidity, reagent concentration and interfering species were investigated. The method has proved to be rapid (80 samples per hour). The RSD of this method was found to be 0.7%. The detection limit for the determination of Mo in steels was found to be 0.05 ppm and the calibration graph is linear up to 200 ppm. The results agreed with those obtained by atomic absorption spectrometry with standard addition method and with certified values of standard reference samples.

"Optimised Calibration Procedure For Bioanalytical Determination Of Organophosphate Pesticides In Apple Juices By Immobilised AChE"
Acta Chim. Slov. 2003 Volume 50, Issue 3 Pages 383-394
Klavdija Mežnar, Boris Pihlar, Lea Pogačnik, Mladen Franko*

Abstract: The bioanalytical method, based on flow injection analysis (FIA), was optimized for detection of organophosphate pesticides in apple juices. The matrix effects (pH value of the sample and presence of alkaline and alkaline earth metal ions) were studied. The activity of acetycholinesterase (ACHE), immobilized on controlled porosity glass, was found to be strongly dependent on the pH value of the mobile phase, which also influences the enzyme inhibition. The optimal pH value was found to be at 7.4. The presence of 0.1 M alkaline and alkaline earth metal ions decreased the enzyme activity for about 20%. In addition, a notable effect on the process of enzyme inhibition by pesticide paraoxon, which was chosen as a model organophosphate pesticide, was observed already when the concentrations of investigated ions were between 0.001 M and 0.01 M. For calibration purposes the standard solutions of paraoxon therefore need to be prepared with the addition of metal ions in concentrations corresponding to those present in investigated apple juice and the pH value of apple juice adjusted to 7.4 by the addition of Tris buffer.