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
Website: @unf

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Classification: Pharmaceutical -> cream

Citations 7

"Analysis Of Neomycins A, B And C By High Performance Liquid Chromatography With Post-column Reaction Detection"
J. Pharm. Biomed. Anal. 1985 Volume 3, Issue 3 Pages 259-267
J. A. Apffel*, J. Van Der Louw, K. R. Lammers, W. Th. Kok, U. A. Th. Brinkman, R. W. Frei and C. Burgess

Abstract: Powdered tablets were dissolved in 15 mM Na acetate buffer (pH 7) for analysis. Lotions, creams or ointments were mixed with CHCl3 and extracted with buffer solution and the aqueous phase was analyzed. Optimum separation was achieved on a column (15 cm x 4.6 mm) of LiChrosorb RP-2 (5 µm) with a mobile phase of Na dodecyl sulfate (75 mg l-1) - 0.5 M Na2SO4 - 15 mM Na acetate buffer (pH 7) and post-column derivatization with phthalaldehyde - mercaptoethanol and fluorescent detection. The coefficient of variation for neomycins A, B and C were 2.9, 1.8 and 1.5%, respectively, and the detection limits were 0.4 ng for A and 5 ng for B and C.
Neomycin A Neomycin B Neomycin C HPLC Fluorescence Post-column derivatization

"Flow Injection Spectrophotometric Determination Of Piroxicam"
J. Pharm. Biomed. Anal. 1993 Volume 11, Issue 10 Pages 933-938
C. Sánchez-Pedreño*, M. S. Garcia, M. I. Albero and J. Rodriguez

Abstract: Methanolic sample solution was injected into a carrier stream of methanol (1.2 ml/min) which merged with a stream of methanolic 0.1 M HCl and passed through a reaction coil (70 cm long) before detection at 332 nm. Alternatively, the carrier stream merged with a stream of methanolic 5 mM Fe(III); in this instance, detection was at 520 nm. Calibration graphs were linear for 0.15-15 and 30-500 µg/ml of piroxicam with use of detection at 332 and 520 nm, respectively; corresponding detection limits were 0.15 and 7.5 µg/ml. Recoveries were >98% for the two methods, and sample throughput was 90/h. The method was used to analyze suppositories, tablets, capsules, creams and ampoules. Two flow injection analysis (FIA) methods are proposed for the determination of piroxicam. The first involves measurement of the UV absorbance of a solution containing the drug, methanol and hydrochloric acid at 332 nm; in the second method a Fe(III)-piroxicam complex is formed in a methanolic medium and the absorbance is measured at 520 nm. In both methods, the peak height is used as a quantitative parameter and piroxicam is determined over the ranges 0.5-15 and 30-500 µg mL-1, respectively. The methods have been applied to the routine determination of the drug in dosage forms.
Piroxicam Spectrophotometry Complexation

"Flow Injection Spectrofluorimetric Determination Of Flufenamic And Mefenamic Acid In Pharmaceuticals"
J. Pharm. Biomed. Anal. 1995 Volume 13, Issue 9 Pages 1113-1117
M. I. Albero, C. Sanchez-Pedreño* and M. S. Garcia

Abstract: Capsule powder or suppositories equivalent to 250 mg mefenamic acid (I) were dissolved in 96% ethanol, filtered and the filtrate was diluted with ethanol. Cream was dissolved in ethanol. Portions (84 µL) were injected into a stream (1 ml/min) of ethanolic 3.7 mM Al(III), passed through a reactor (1.6 m x 0.5 mm i.d.) and the fluorescence was measured at 440 nm (excitation at 351 nm) for flufenamic acid (II) or at 454 nm (excitation at 355 nm) for I. The calibration graphs were linear for 0.02-1.2 and 0.3-16.1 µg/ml II and I, respectively, and the corresponding quantitation limits were 0.008 and 0.18 µg/ml. The RSD were 1.26% and 1.3%, respectively (n = 10); no interference was observed. Sample throughout was 90/h. The results agreed well with those obtained by the titrimetric British Pharmacopoeia method. Recoveries were 98-101%. Two sensitive and rapid flow injection (FI) spectrofluorimetric methods are proposed for the determination of flufenamic acid (FF) and mefenamic acid (MF), based on the formation of complexes of these compounds with A1(III) in an ethanolic medium. The calibration graphs resulting from the measurements of the fluorescence at lambda exc = 351 nm and lambda em = 440 nm, and lambdaexc = 355 nm and lambda em = 454 nm for the complexes with FF and MF, respectively, are linear over the range 0.030-1.20 µg mL-1 for FF and 0.30-16.1 µg mL-1 for MF. The methods have been applied to the determination of these drugs in pharmaceutical preparations.
Drugs Mefenamic acid Flufenamic acid Fluorescence Interferences Method comparison

"Fluorimetric Determination Of Chloroxine Using Manual And Flow Injection Methods"
J. Pharm. Biomed. Anal. 1996 Volume 14, Issue 11 Pages 1505-1511
Tomás Pérez-Ruiz*, Carmen Martínez-Lozano, Virginia Tomás and José Carpena

Abstract: Powdered tablets equivalent to 20 mg chloroxine (5,7-dichloroquinolin-8-ol; I) were shaken with 25 mL 4 M acetic acid, sonicated and diluted to 1 l with water. Topical preparations equivalent to 10 mg I were heated with 25 mL methanol/acetic acid (3:2) and diluted to 1 l with water. For FIA, sample (95 µL) was injected into a stream (1.2 ml/min) of 14 mM sodium lauryl sulfate which was merged with a stream of 0.2 M acetate buffer (0.4 ml/min) of pH 4.2 and then a stream (0.4 ml/min) of 2.5 mM AlCl3. After passing through a reactor coil (60 cm x 0.5 mm i.d.) the fluorescence was measured at 496 nm (excitation at 399 nm). A batch method was also carried out (details given) in which the calibration graph for I was linear for 20 nM- to 51 µM-I and the detection limit was 5 nM. For FIA, the calibration graph was linear for 0.56-56 µM-I, and the detection limit was 0.13 µM. RSD were 2.3% and 0.38% for the batch and FIA methods, respectively. Recoveries were 96-103%.
Chloroxine Fluorescence Method comparison Buffer Method comparison

"Construction And Evaluation Of PVC Conventional And Tubular Tripelennamine-selective Electrodes: Their Application In Pharmaceutical Preparations"
J. Pharm. Biomed. Anal. 1996 Volume 14, Issue 8-10 Pages 931-938
J. L. F. C. Limaa, M. C. B. S. M. Montenegroa,* and M. G. F. Salesa

Abstract: Conventional membrane-ISE for tripelennamine were fabricated using PVC membranes doped with tripelennamine tetraphenylborate as ionic-exchanger and 2-nitrophenyl octyl ether (type A), dibutylphthalate (type B) or bis-(2-ethylhexyl)sebacate (type C) as plasticizer. These electrodes gave a linear response to 40 µM-0.1 M tripelennamine in 0.1 M phosphate buffer at pH 7 with a fast response time (20 s) and a high reproducibility (±0.2 mV per day). Type A electrode exhibited good selectivity towards tripelennamine in the presence of interferents such as sodium, potassium, lithium, ammonium, chlorpheniramine, diphenydramine, promethazine, meclizine and pentazocine. The type A membrane was used to construct a tubular detector for used in FIA systems. In FIA systems with 0.1 M phosphate carrier stream (6 ml/min), the performance of the tubular detector was similar to that of conventional ISE. The FIA system was used to analyze pharmaceutical preparations (creams, syrups and gels) and mean recoveries of 99.8-100.6% were achieved.
Tripelennamine Electrode Interferences

"Flow Injection Spectrophotometric Determination Of Silver In Pharmaceutical Preparations Using Rhodamine B"
Quim. Anal. 1994 Volume 13, Issue 3 Pages 131-133
Goncalves Pereira, K.A.;Santelli, R.E.

Abstract: Pharmaceuticals containing silver vitelinate (collyrium and decongestant) or silver sulfadiazine (cream) were analyzed. The collyrium and decongestant were dissolved in concentrated HNO3 and then diluted with 25 mM H2SO4. The cream was heated with concentrated HNO3 at 80°C for 1 h to complete solubilization followed by dilution as above. The sample solution (450 µL) was introduced into the carrier stream (2.2 ml/min) of 25 mM H2SO4 and merged with aqueous 2% ammonium thiocyanate (0.4 ml/min). After passing through a reaction coil (50 cm x 0.8 mm i.d.), the stream was merged with a reagent stream (0.4 ml/min) of Rhodamine B reagent (0.2 mM Rhodamine B, 0.1% PVA and 0.66 M H2SO4) and passed through a reaction coil (100 cm x 0.8 mm i.d.). The sample rate was 80/h and the absorbance of the colored complex was measured at 600 nm. Calibration graphs were linear for 0.1-0.8 µg/ml of Ag with a detection limit of 20 ng/ml; the RSD (n = 11) was 3%. Results (tabulated) compared well with those obtained by AAS.
Silver Spectrophotometry Spectrophotometry

"Electrochemical Determination Of Minoxidil In Different Pharmaceutical Formulations By Flow Injection Analysis"
Anal. Sci. 2006 Volume 22, Issue 1 Pages 91-94
Valeria Pfaffen And Patricia I. Ortiz

Abstract: The electrochemical behavior and amperometric-FIA quantification of minoxidil at a glassy carbon electrode is described. The procedure is based on electrochemical oxidation at 0.800 V (vs. Ag/AgCl/NaCl(3 M) in a phosphate buffer solution. Minoxidil was determined over the range 1 x 10^-7 - 1 x 10^-4 M. Different analytical parameters and electrode stability were analyzed to obtain the best electrode performance. The optimal conditions were: working potentials, 0.800 V; flow rate, 0.74 mL min-1; and solution pH 7.0. This system allowed a sampling rate of 120 samples per hour without any pretreatment. The proposed method was used for minoxidil quantification in pharmaceutical preparations with satisfactory results. The accuracy of FIA-amperometric method was established by a comparison with the conventional UV determination technique using a paired t-test indicating the absence of systematic errors.
Minoxidil Amperometry Electrode Method comparison