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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Emulsion

Classification: Mobile Phase -> Emulsion

Citations 16

"Analytical Methodologies For Atomic Spectrometric Determination Of Metallic Oxides In UV Sunscreen Creams"
J. Pharm. Biomed. Anal. 2000 Volume 22, Issue 2 Pages 301-306
A. Salvador, M. C. Pascual-Martí, J. R. Adell, A. Requeni and J. G. March

Abstract: In this study, methodologies for determining titanium oxide, zinc oxide and iron oxide are proposed and assayed in commercial sunscreen products. The proposed methodology for TiO2 determination in sunscreens is based on a microwave-assisted treatment for digesting the organic components in a closed teflon reactor in presence of HNO3 and HCl. Titanium is determined by inductive coupled plasma emission spectrometry (ICP-AES). The proposed methodologies for measuring ZnO and Fe2O3 are based on a sample emulsification in water with a non ionic tensioactive and IBMK, followed by Zn and Fe determination by flame atomic absorption spectrometry (FAAS). The methodologies allow a precise and accurate determination of metallic oxides in UV sunscreen creams, where the sample treatment is less time-consuming than in the classic methods. To our knowledge this is the first study focused to the determination of metallic oxides in commercial sunscreen products.

"The Use Of Microemulsions In Flow Injection Analysis. Spectrofluorimetric Determination Of Primary Amines"
Anal. Chim. Acta 1986 Volume 183, Issue 1 Pages 179-185
M. Hanif Memon and Paul. J. Worsfold

Abstract: Water-in-oil micro-emulsions in flow injection systems were applied to the determination of C6 to C10 primary amines in heptane containing 1,2-bis-(2-ethylhexyloxycarbonyl)-1-ethanesulfonate surfactant. Following derivatization with phthalaldehyde and 2-mercaptoethanol, the primary amine sample was introduced into the micro-emulsion reagent stream and detected fluorimetrically at 432 nm (with excitation at 340 nm). The effects of water-to-surfactant mole ratio, droplet concentration, pH and flow rate on the fluorescence signal were studied. Calibration data are given for hexyl-, octyl- and decyl-amine (up to 50 µM). Flow injection analysis of micro-emulsions could be used with other detection systems, e.g., spectrophotometry or chemiluminescence.
Amines, primary Spectrophotometry Fluorescence Chemiluminescence

"Use Of Microemulsions In Flow Injection Analysis: Spectrophotometric Determination Of Copper"
Anal. Chim. Acta 1987 Volume 201, Issue 1 Pages 345-350
M. Hanif Memon and Paul J. Worsfold

Abstract: Surfactant-promoted micro-emulsions facilitate the extraction and complexation of Cu(II) from aqueous ascorbic acid - Na acetate into heptane containing neocuproine(I). The detergents used are dioctyl sulfosuccinate for water-in-oil emulsions and Na dodecyl sulfate for oil-in-water emulsions, with butanol and pentanol as respective co-surfactants. The I complex is measured at 460 nm. For extraction with water-in-oil emulsions, a coefficient of variation (n = 10) between 0.6 and 2.6% is achieved with an efficiency of 70% from 0.025 to 7.5 mM Cu. The coefficient (n = 10) for oil-in-water emulsions are from 0.3 to 1.9% with an extraction efficiency of 60%.
Copper Spectrophotometry Sample preparation

"Analytical Applications Of Microemulsions. Spectrophotometric Determination Of Zinc Using Dithizone"
Analyst 1988 Volume 113, Issue 5 Pages 769-771
M. Hanif Memon and Paul J. Worsfold

Abstract: Oil-in-water emulsions comprising 0.16 M Na dodecyl sulfate - 3-methylbutanol - heptane (43:5:2) were used. The absorbance of the Zn - dithizone complex was measured at 540 nm, a rectilinear response being obtained up to 10 mg L-1 of Zn. The coefficient of variation (n = 10) was 0.4% for 10 mg l-1. The procedure could be adapted to flow injection analysis without loss of sensitivity other than online dilution.
Zinc Spectrophotometry Sample preparation

"Speciation Of Tetraalkyllead Compounds By Flow Injection - Atomic Absorption Spectrophotometry"
Fresenius J. Anal. Chem. 1990 Volume 338, Issue 1 Pages 9-15
R. Borja, M. de la Guardia, A. Salvador, J. L. Burguera and M. Burguera

Abstract: To determine total Pb in liposoluble samples (e.g., gasoline), containing tetraethylstannane (I) and tetramethylstannane (II), samples (100 µL) were injected into a carrier stream (2.4 mL min-1) of aqueous 0.1% Emulsogen M in one channel of a double-channel manifold and were demetallated by a 200 µL injection of 6% iodine solution in light petroleum into the other channel. The two channels converged before demetallation in a reaction coil of length 300 cm and emulsification in a 2.8 mL PTFE stirred dilution chamber. Lead was determined in an air - acetylene flame. The two compounds were determined individually by single injection (i.e., without the iodine) into the flow system followed by emulsification; the carrier flow rate was 16.6 mL min-1 and a coil of length 25 cm was used. The theory is presented. The detection limits for total Pb, for I as Pb and for II as Pb were 43, 0.8 and 0.6 µg g-1, respectively.
Lead Spectrophotometry

"Flow Analysis Preconcentration Of Magnesium And Zinc Using Emulsions For Flame Atomic Absorption Spectrometry"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 7 Pages 860-863
T. Yokoyama, Takashi Watarai, Takeo Uehara, Koh-ichi Mizuoka, Kenji Kohara, Masato Kido, Michio Zenki

Abstract: A pre-concentration method combining Water/Oil/Water (W/O/W) emulsions with flow injection manifolds has been developed for determinations of Mg and Zn. The system consists of a mixing coil filled with Span 80 as a surfactant, palmitic acid or di(2-ethylhexyl) phosphate as an extractant, kerosene as a solvent in the oil phase, and HCl in the inner aqueous phase to form W/O emulsions, an extraction coil for the sample solution to form W/O/W emulsions, a phase separator to waste the outer aqueous phase, a dry bath to demulsify W/O emulsions with 2-ethylhexanol, a phase separator to waste the oil phase, and an air pump to deliver the concentrated sample solution to the flame atomic absorption spectrophotometer. This method proved to be excellent regarding the reproducibility, the rapidity, and the small quantity of sample, compared with the W/O/W emulsions method without the flow injection manifolds. The signal of flame atomic absorption spectrometry (FAAS) after pre-concentration of Mg by this method was 2.4 times as large as that before pre-concentration. Also, this method suppressed some interferences. The system was applied to FAAS determinations of Mg and Zn in duralumin alloys and Zn in commercial reagents. 10 References Samples were injected into a stream (2.4 ml/min) of water, which merged with an emulsified stream of 0.55-1.1 M HCl and kerosene containing 0.4-0.5% Span 80 (Nacalai tesque, Kyoto, Japan) and 0.5-2% palmitic acid (details given) then passed through a PTFE extraction coil (10 m x 0.5 mm i.d.) and a phase separator. The emulsion then merged with a stream (0.4 ml) of 2-ethylhexanol (demulsifier), and passed through a dry bath at 130°C for demulsification (details given) and a second phase separator; the aqueous phase was carried in air (42 ml/min) to an AAS instrument for analysis. The detection limits using 1 mL samples were 20 ng/ml Mg and 100 ng/ml Zn. The calibration graphs were linear from 20-200 and 100-500 ng/ml, respectively. RSD and recoveries are not given. The method was applied to commercial reagents and duralumin alloys (results presented).
Magnesium Zinc Duralumin Alloy Inorganic compound Spectrophotometry Sample preparation

"Solubilized Substrates For The Online Measurement Of Lipases By Flow Injection Analysis During Chromatographic Enzyme Purification"
Anal. Biochem. 1992 Volume 202, Issue 1 Pages 16-24
Gabriele C. Chemnitius, Helmut Erdmann* and Rolf D. Schmid

Abstract: A modular flow injection system was applied in the online assay of lipases. Substrate emulsion and lipase solution were simultaneously injected into carrier stream 1 and carrier stream 2, respectively, the carrier streams were combined and passed through a thermostated reaction coil before being passed to the photometer. 1,2-O-didodecyl-rac-glycero-3-glutaric resorufin ester was the preferred substrate with a reaction coil temperature of 37°C. With a combination of stopped-flow technique and zone sampling and detection at 571 nm, calibration graphs were rectilinear up to 800 IU mL-1 of lipase from Staphylococcus carnosus. Results for lipases from other species are presented. A flow injection analysis (FIA) system for the online measurement of lipases in chromatography processes was developed. The photometrically detectable substrates, p-nitrophenyl palmitate, S,O,O'-tripropyryl-1-thioglycerol, and 1,2-O-dilauryl-rac-glycero-3- glutaric resorufin ester were investigated. Different detergents and qualities of assay emulsions were tested for optimal results in FIA applications. Emphasis was placed on increasing the stability of the assay emulsion. Lipases of different origin and specificity were detected. The linear detection range was adapted to the requirements of the chromatography purifn. procedures. The connection of the FIA with a fast-protein liquid chromatography system permitted the automatization of lipase purifn. by monitoring protein content, salinity, and enzyme activity of the effluent from column chromatography.
Enzyme, lipase LC Spectrophotometry

"Comparison Of Aqueous, Micellar And Microemulsion Carriers In Flow Injection Analysis. The Base Hydrolysis Of Acetylsalicylic Acid"
Anal. Lett. 1988 Volume 21, Issue 4 Pages 583-598
Stephen H. Brooks, Richard N. Williams and John G. Dorsey

Abstract: The potential applicability of surfactant solutions as carrier streams in flow injection analysis is examined. The reaction rates determined for the base catalyzed hydrolysis of acetylsalicylic acid in aqueous, micellar and microemulsion solutions show a rate enhancement of 40% for the static microemulsion system when compared to the aqueous solution. However, when the identical microemulsion solution is employed as a carrier stream in flow injection analysis with ultraviolet detection, this enhancement in rate is not observed. To our knowledge, all previous work employing microemulsions in FIA has been concerned only with detection enhancement, here we present direct comparisons between aqueous and microemulsion carriers concerning rates of reaction, peak dispersion and analytical figures of merit. The loss in relative sensitivity can be traced to the increased dispersion in the microemulsion system (D = 14.36) when compared to the aqueous carrier (D = 12.52). Additionally, an increased skewness was observed in the peaks obtained with a microemulsion carrier, yielding further information about the physical dispersion process occuring in the sample plug.
Acetylsalicylic acid Aspirin Spectrophotometry

"Chemiluminescence Property Of The Luminol-hydrogen Peroxide-copper(II) System In The Presence Of Surface-carboxylated Microspheres"
Anal. Sci. 1998 Volume 14, Issue 2 Pages 409-412
Kazuhiko TSUKAGOSHI, Masayuki SUMIYAMA, Riichiro NAKAJIMA, Masamichi NAKAYAMA and Mizuo MAEDA

Abstract: The cathodoluminescence was studied of a luminol-hydrogen peroxide-copper(II) system in the presence of surface-carboxylated microspheres. The results should provide important information not only concerning anal. applications of the cathodoluminescence reaction in an emulsion, but also to a specific liq.-solid interface chemical using microspheres as functional materials.
Chemiluminescence

"Analytical Applications Of Microemulsions"
Anal. Proc. 1986 Volume 23, Issue 12 Pages 418-419
M. Hanif Memon, Paul J. Worsfold

Abstract: Flow injection procedures, with fluorimetric detection, in which the reagent is solubilized in a water - oil emulsion stabilized by Aerosol-OT, are described. Reactions between a non-aqueous sample (containing, e.g., C6 to C10 primary amines) and an aqueous reagent (e.g., phthalaldehyde - 2-mercaptoethanol) are studied quantitatively from 0 to 50 µM-amine. Triacylglycerol lipase is determined (range 0 to 5000 iu l-1) by enzymatic cleavage of 4-methylumbelliferyl heptanoate, solubilized in a micro-emulsion.
Amines Triacylglycerol lipase Fluorescence

"Flow Injection Determination Of Organosulfur Compounds With Chemiluminescence Detection"
Anal. Proc. 1989 Volume 26, Issue 1 Pages 19-20
J. Steven Lancaster, Paul J. Worsfold

Abstract: A flow injection system is described and illustrated, for determination of 2-(ethylthio)phenol (I) in a carrier stream of acetone, with an oxidant stream of 1 M NaOCl in 0.1 M HCO3- buffer of pH 11.0 (both 1.0 mL min-1); chemiluminescent detection was used. The calibration graph (log. - log.) of concentration. vs. emission intensity was rectilinear from 1 to 50 mM I, and the detection limit was 0.4 mM. The coefficient of variation (n = 10) ranged from 1.6 to 22.8%.
2-Ethylthiophenol Chemiluminescence

"The Use Of Emulsions In Atomic Spectrometry And Flow Injection Analysis: Fundamentals And New Applications"
Analusis 1991 Volume 19, Issue 6 Pages M52-M56
DE LA GUARDIA M. ; SALVADOR A.

Abstract: A review is presented, with 32 references, of emulsification sample preparation techniques for use in the direct determination of metals in liposoluble samples by the cited methods.
Metals Spectrophotometry

"A New Method To Determine Enzyme Activities In Two-phase Systems By Flow Injection Analysis"
Biosens. Bioelectron. 1998 Volume 13, Issue 7-8 Pages 925-930
M. Becker* and U. Spohn

Abstract: The activity of phospholipase D (PLD) from Streptomyces chromofuscus in two-phase systems consisting of a PLD containing aqueous phase and a phosphatidylcholine (PC) containing organic solvent phase was investigated. Two-phase systems with highly reproducible segmentation were generated in a continuous-flow system using a capillary segmentor. Between 0.01 and 2 U/mL PLD from Streptomyces chromofuscus were detected in a water/hexane two-phase system. The linear detection range was 0.01 to 0.5 U PLD/mL. The apparent KM of Streptomyces chromofuscus PLD in a water/hexane system was 41.43 µM PC, the apparent Vmax was 3.68 µmol min-1 mg-1. The variation of PLD activity in different organic solvents correlated with the solvent's hydrophobicity. If anionic detergents or primary alcohols were added to the two-phase system, concentration dependent activation of the PLD was observed
Enzyme, activity Enzyme, phospholipase D Bacteria

"Flow Injection Determination Of A Primary Bile Acid (cholyl Glycine) [glycocholic Acid] Using Co-immobilized Bacterial Luciferase And Oxidoreductase"
J. Chem. Soc. Pak. 1989 Volume 11, Issue 2 Pages 127-129
Nabi, A.;Worsfold, P.J.

Abstract: Aqueous sample or standard (1 µM to 10 mM) solution of glycocholic acid was injected into a stream of 0.5 mM NAD+ - 0.1 mM dithiothreitol in 50 mM phosphate buffer of pH 7.5, and simultaneously 1 µM-oxidized flavine mononucleotide was injected into a stream of 50 mM phosphate buffer of pH 7.5 containing 0.001% of emulsified decanal. The injection volume were both 30 µL and the flow rates both 0.4 mL min-1. The merged streams passed through a glass coil (6 cm x 2.5 mm) containing 7α-hydroxysteroid dehydrogenase and Vibrio harveyi alkanal monoxygenase (FMN-linked) and oxidoreductase all immobilized on Sepharose 4B beads [cf. Analyst (London), 1986, 111, 1321], and the resulting bioluminescence was detected with an end-window photomultiplier tube. The calibration graph was rectilinear for 1 µM to 1 mM glycocholic acid, and the coefficient of variation (n = 5) were 3.4%. The throughput was 60 per h.
Bile acid Glycocholic acid Bioluminescence

"Circulating Solvent Extraction System For Trace Metals In Aqueous Solution"
J. Trace Microprobe Tech. 1989 Volume 7, Issue 1-2 Pages 103-110
Yoshimura, E.;Toda, S.

Abstract: Sample solution containing the chelated analyte is mixed with organic solvent in a funnel, the tapering end of which is packed with pieces (2 mm x 1 mm) of porous PTFE film to break any emulsion. The two-phase percolate meets a porous PTFE bobbin phase separator (6 cm x 1 cm diameter) through which only the organic phase passes, the aqueous phase being returned by a pump to the funnel. The organic phase drips into a vessel containing magnetically stirred acidic aqueous back-extractant, wherein the analyte is concentrated while the organic phase is sucked through a further PTFE phase separator (4 cm x 1 mm diameter) to a solvent reservoir from which solvent is pumped to the funnel. For 0.1 µg mL-1 each of Zn and Cd chelated with diethyldithiocarbamate in a 2-l sample, respective concentration. factors of 51 and 34 were attained with use of 70 mL of CHCl3 and 20 mL of 1 M HCl. Projected improvements to the system are briefly discussed.
Zinc Cadmium Sample preparation

"Direct Determination Of Calcium In Lubricating Oils By Flow Injection Atomic Absorption Spectrometry Using Emulsions"
Quim. Anal. 1989 Volume 8, Issue 2 Pages 241-246
Borja, R.M.;Salvador, A.;De La Guardia, M.;Burguera, J.L.;Burguera, M.

Abstract: Oil samples were injected (100 µL; 0.5 to 5% in isobutyl methyl ketone) into a stream (0.2 mL min-1) of water and mixed with a stream (1.83 mL min-1) of a surfactant (aqueous 20% Nemol K39) ultrasonically in a 2-m reaction coil, and carried directly into the nebulizer of an AAS instrument. Results by flow injection analysis - AAS were more sensitive and precise than the batch method; coefficient of variation were 2.2 to 2.8%.
Calcium Oil Spectrophotometry