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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Desire L. Massart

Abbrev:
Massart, D.L.
Other Names:
Address:
ChemoAC, Pharmaceutical Institute, Free University of Brussels, Laarbeeklaan 103, B-1090 Brussels, Belgium
Phone:
+32-2-477-4737
Fax:
+32-2-477-4735

Citations 6

"Development And Optimisation Of A Flow Injection Assay For Fluticasone Propionate Using An Asymmetrical Design And The Variable-size Simplex Algorithm"
J. Pharm. Biomed. Anal. 2000 Volume 23, Issue 2-3 Pages 291-306
C. Vannecke, A. Nguyen Minh Nguyet, M. S. Bloomfield, A. J. Staple, Y. Vander Heyden and D. L. Massart

Abstract: A flow injection analysis method is described to determine fluticasone propionate, based upon a novel adaptation of the reaction of o-phthalaldehyde with a thiol and a primary amine. The method, which allows both UV and fluorescence detection, has been optimized using experimental design. First a screening is executed to select the significant factors acid in a second step these factors are optimized with the variable-size simplex algorithm. In the screening step, a two-level fractional factorial design is compared with an asymmetrical design containing the same number of experiments, but in which one factor is at three levels. It was found that in both designs the same significant variables are detected for the two-level factors, but that for the three-level factor the asymmetrical design confirms an expectation of having a (local) optimum in the examined domain, whilst from the two-level design this is not at all apparent. Complete optimization was carried out for both UV and fluorescence detection. The two detection methods did not have the same significant variables. For the UV detection, the temperature and the pH adjustment on-line (concentration of sodium hydroxide and amount of boric acid) were the most critical parameters. For the fluorimetric detection the temperature and the fraction of methanol were critical. Moreover the conditions found to be optimal are different for both detection methods.
Optimization

"Use Of Experimental Design To Optimise A Flow Injection Analysis Assay For L-N-monomethylarginine"
J. Pharm. Biomed. Anal. 1999 Volume 21, Issue 2 Pages 241-255
C. Vannecke, M. S. Bloomfield, Y. Vander Heyden and D. L. Massart

Abstract: A flow injection analysis (FIA) method to determine L-N-monomethylarginine, based on the reaction with ortho-phthalaldehyde in the presence of a suitable thiol-group, was optimized using experimental design. Two different approaches were followed wherein, (i) critical factors were identified in a screening design, and (ii) the simplex algorithm was used for further optimization. In the first approach, the chemical reaction was optimized off-line and the optimal chemical conditions were transferred to the FIA-system. In the second approach the reaction and the FIA-system parameters were optimized together. The online approach is preferred.

"An Experimental Design Approach To The Optimisation Of A Flow Injection Analysis Method For Glycine"
J. Pharm. Biomed. Anal. 1999 Volume 18, Issue 6 Pages 963-973
C. Vannecke, S. Baré, M. Bloomfield and D. L. Massart

Abstract: A flow injection analysis method for the determination of glycine, based on the reaction with ortho-phtalaldehyde and N-acetylcysteine in a basic buffer, was optimized. In the first step screening of the variables, to select the most important ones, was performed using: (i) a half-fraction factorial design and (ii) a quarter-fraction factorial design, for five factors at two levels. The effects of the factors on the peak height were calculated from both screening designs and compared. For the half-fraction factorial design (resolution IV), the significance of the factor effects on the peak height was checked by: (i) comparing them with a critical effect, calculated from two-factor interactions and based on a t-test, (ii) using a non parametric approach and (iii) drawing a normal probability plot. For the quarter-fraction factorial design (resolution III) the significance of the effects of the factors on the peak height was checked using: (i) a randomization test method, (ii) the non parametric method and (iii) a normal probability plot. In the second step, the factor found to be of importance was optimized using the uniplex method.

"Kinetic Study Of The Fluoride Electrode In Fast Flow And Automatic Systems"
Anal. Chem. 1976 Volume 48, Issue 2 Pages 272-277
John Mertens, Pierre Van den Winkel, and Desire L. Massart

Abstract: The kinetics of the fluoride [16984-48-8] ion-sensitive electrode were investigated by the fast flow injection method and in systems for automatic anal. The kinetics observed in injection experiments do not fit in with the equations proposed by Rechnitz, Johansson, and Pungor for glass and some other ion-selective electrodes. When t90 (time to reach 90% of equilibrium. potential) is ≤2 sec, a hyperbolic relation is observed No simple equation is able to describe the response when it is slower. There is a discrepancy between the dynamic responses measured in the injection method and that observed in auto-analyzers. It is proposed that the rate-limiting step in the latter case is film diffusion. The slowing-down effect can be considerably decreased by using internally stirred electrode cells. Responses allowing sample rates up to 60/hr can then be expected. With a discontinuous system, in which very high flow rates are applied, sample rates of 100/hr are possible.
Fluoride Electrode Kinetic Apparatus

"Development Of A Generic Flow Injection Analysis Method For Compounds With A Secondary Amine Or Amide Function, Using An Experimental Design Approach Part II. Selection And Evaluation Of The Chemical Reaction Parameters"
Anal. Chim. Acta 2002 Volume 455, Issue 1 Pages 117-130
C. Vannecke, M. S. Bloomfield, Y. Vander Heyden and D. L. Massart

Abstract: A second part in the development of a generic flow injection analysis (FIA) method to determine compounds with a secondary amine or amide in their structure is described. This part consists in the selection and evaluation of the chemical reaction conditions. Sodium hypochlorite first converts the secondary amine or the amide to a primary amine. The latter reacts with o-phthalaldehyde (OPA) and a thiol (N-acetylcysteine (NAC)) to form a derivative which can be measured fluorimetrically. To investigate the influence of the different chemical reaction parameters on the peak height for a set of 31 pharmaceutical compounds, a quarter-fraction factorial design for six factors at two levels (2(6-2) -resolution IV, 16 experiments) was executed. Effects on the responses were calculated for each compound. Parallel coordinate geometry (PCG) plots and principal component analysis (PCA) were also applied on the measured responses as aids in the interpretation of the results.

"Development Of A Generic Flow Injection Analysis Method For Compounds With A Secondary Amine Or Amide Function, Using An Experimental Design Approach I. Selection And Evaluations Of The FIA System Parameters"
Anal. Chim. Acta 2001 Volume 446, Issue 1-2 Pages 411-426
C. Vannecke, E. Van Gyseghem, M. S. Bloomfield, T. Coomber, Y. Vander Heyden and D. L. Massart

Abstract: A generic flow injection analysis (FIA) method to determine compounds with a secondary amine or an amide in their structure was developed. A first part of the development, namely the selection and evaluation of the FIA system, is described. A chemical reaction with sodium hypochlorite (NaOCI) first converts the secondary amine or the amide to a primary amine. This is followed by reaction of the primary amine with o-phthataldehyde (OPA) and a thiol (N-acetylcysteine, NAC), to form a derivative which can be measured fluorimetrically. To investigate the influence of the different FIA system parameters on both the peak height and the residence time for a set of 28 pharmaceutical compounds, a half-fraction factorial design for five factors at two levels (2(5-1): resolution V = 16 experiments) was executed. Effects on both responses were calculated. Since the peak height should be maximized and the residence time minimized, the Pareto optimality concept was applied to make an optimal compromise between both responses and to eventually select a generic FIA system.