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 -> drop

Citations 4

"Flow Injection Analysis Of Mercury(II) In Pharmaceuticals Based On Enzyme Inhibition And Biosensor Detection"
J. Pharm. Biomed. Anal. 1999 Volume 20, Issue 1-2 Pages 263-269
P. Bertocchi, E. Ciranni, D. Compagnone, V. Magearu, G. Palleschi, S. Pirvutoiu and L. Valvo

Abstract: An enzymatic amperometric procedure for measurement of mercury(II) in pharmaceuticals, based on the inhibition of invertase and on a glucose electrode was studied. Analytical parameters for measurements in batch and flow injection analysis (FIA) have been optimized. Mercury(II) was detected in the 10^-60 ppb range with RSD less than or equal to 2%. A sample throughput of 6 h-1 for batch and 15 h-1 for FIA was obtained. The total mercury(II) from thimerosal (thiomersal, sodium ethylmercurithiosalicylate) in eye-drop samples was measured with the amperometric procedure after oxidative cleavage treatment. Results for both batch and FIA procedures correlated well with atomic absorbtion spectroscopy (AAS) data.
Mercury(II) Sensor Method comparison Optimization

"Indirect Flame Atomic Absorption-spectrometric Determination Of Papaverine, Strychnine And Cocaine By Continuous Precipitation With Dragendorff Reagent"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 8 Pages 1117-1120
Marcelina Eisman, Mercedes Gallego and Miguel Valcárcel

Abstract: Samples of injection solution, oral drops or syrup were dissolved in H2O; ground tablets were extracted with water and the extract was filtered. The FIA system comprised blank and sample streams, into either of which Dragendorff reagent (0.8 mM tetraiodobismuthate of pH 2.0) was injected. The pH of the sample stream was 5.1-7.2 for papaverine (I), 3.5-7.5 for strychnine (II) or 3.0 for cocaine (III). The resulting stream was passed through a 200 cm mixing coil and filter and analyzed for Bi by flame AAS. The difference in absorbance between the sample and blank (H2O for I or II, 1 mM HCl for III) streams was related linearly to the concentrations of I, II and III over the ranges 1.5-18, 4-60 and 6-100 µg/ml with detection limits of 0.8, 1.5 and 2.5 µg/ml, respectively. The effects of pH, flow rate and temperature were investigated. The tolerance limits towards other common alkaloids are reported.
Papaverine Strychnine Cocaine Spectrophotometry Indirect Precipitation Interferences Filter

"FIA Titrations Of Ephedrine In Pharmaceutical Formulations With A PVC Tetraphenylborate Tubular Electrode"
J. Pharm. Biomed. Anal. 1995 Volume 13, Issue 4-5 Pages 459-464
Manuel N. M. P. Alçada, JoséL. F. C. Lima and M. Conceição B. S. M. Montenegro*

Abstract: To prepare membranes for the tubular electrodes, 25 mL 0.1 M sodium tetraphenylborate were mixed with 20 mL 0.1 M tetrapentylammonium bromide in acetone, and the acetone was evaporated. The resulting crystals (0.06 g) were dissolved in 2.42 g 2-nitrophenyl-phenyl ether and portions (0.4 ml) of the resulting solution were mixed with 0.18 g PVC. Tubular electrodes were constructed as described previously (Lima et al., J. Flow Injection Anal., 1990, 7, 19) and applied to the flow injection analysis of ephedrine hydrochloride (I) in pharmaceuticals. Liquid samples equivalent to 2.5 mg I were diluted to 25 mL in phosphate buffer of pH 6.3. Powdered tablets equivalent to 12.6 mg I were dissolved in 25 mL phosphate buffer. Portions (80 µL) were injected into a carrier stream (6.8 ml/min) of 0.1 mM sodium tetraphenylborate in phosphate buffer. After passage through a mixing chamber (details given), potentiometric measurements were made vs. an Orion 90-02-00 double-junction reference electrode. The calibration graph was linear from 0.2-2 mM I and the RSD were 1.5%. Sample throughput was 60/h. The mean recovery of I in pharmaceuticals was 98.6% with a RSD of 2.5%. A flow injection system for the titration of ephedrine in pharmaceutical products with potentiometric detection was developed. For this purpose a tetraphenylborate tubular electrode was constructed. The electrode was prepared without inner reference solution and with a PVC membrane based on tetrapentylammonium tetraphenylborate as ion exchanger and 2-nitrophenylphenyl ether as mediator solvent. Its operational characteristics were evaluated in a low dispersion manifold and compared with more conventionally shaped electrodes using the same sensor. In the pH range 2.5-11.5, the electrodes showed linear response between 3.8 x 10^-6 and 0.1 M with a slope of -56.4 mV/log[BPh4]. Ephedrine determinations in pharmaceutical products were carried out in a single channel manifold with a mixing chamber incorporated and using the tubular electrode as detector. Recovery rates of 98.6±2.5% were obtained in the analysis of tablets, nasal drops and syrups with a sampling rate of about 60 h-1.
Drugs Ephedrine hydrochloride Electrode Potentiometry Electrode Mixing chamber Titrations

"FIA - Fluorimetric And Spectrophotometric Determination Of 3,6-diaminoacridine (proflavine)"
Pharmazie 1989 Volume 44, Issue 11 Pages 795-796
Martinez Calatayud, J.;Sanchez Sampedro, A.;Villar Civera, P.;Gomez Benito, C.

Abstract: A 312 µL portion of proflavine solution (I) was injected into a carrier stream (flow rate 2.1 mL min-1) at neutral or slightly acidic pH, and the absorbance was monitored at 450 nm after mixing in a 33-cm coil. A medium of water or aqueous 60% DMF (pH 5 to 7) was used for fluorimetry; respective sample volume, flow rate and coil length were 312 and 263 µL, 2.83 and 4.14 mL min-1 and 33 and 83 cm. The fluorescence was measured at 507 nm, with excitation at 450 nm in water or at 447 nm in aqueous DMF. Response was rectilinear for up to 41, 1.9 and 8.1 µM-I by the spectrophotometric and the H2O- and aqueous DMF-based fluorimetric methods, respectively, with corresponding coefficient of variation of 1.2, 0.3 and 0.4% and sample throughputs of 40, 63 and 97 h-1. The methods were applied in the analysis of eye-drops; relative errors were 1%.
3,6-Diaminoacridine Spectrophotometry Fluorescence Organic phase detection