Bromate assay in water by inductively coupled plasma mass spectrometry combined with solid-phase extraction cartridges

Cai, Qingyun; Guo, Zhe; Yu, Chunhai; Zhang, Wei; Yang, Zhaoguang

doi:10.1007/s00216-003-2151-3

“…Bromide ions could not be detected by AgNO 3 in the TTAOH stock solution (Ag + + Br À !AgBrfl), so the ion exchange with hydroxide is > 99 %. [9] The critical micelle concentration (cmc) of TTAOH (0.0018 mol L À1 ) was determined by using surface tension measurements. Oleic acid (OA) was obtained from Shanghai Chemical Co. with ionic impurities of sodium (0.1 % molar fraction) and calcium (0.05 % molar fraction).…”

Section: Methodsmentioning

confidence: 99%

“…The resulting ion exchange with hydroxide ions was > 99 % (as determined from the detection limit of Br À ions (Br À sensitivity)). [9] The critical micelle concentration (cmc) of TTAOH was determined by surface tension measurements to be 1.8 mmol L À1 . The phase behavior on mixing 100 mm TTAOH with increasing concentrations of OA (up to 200 mm) was studied (not shown here).…”

mentioning

confidence: 99%

An Onion Phase in Salt‐Free Zero‐Charged Catanionic Surfactant Solutions

Song

¹

,

Dong

²

,

Jia

³

et al. 2005

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Mixtures of cationic and anionic (catanionic) single-chain surfactants can readily form bilayers in aqueous solutions, [1] in which uni-and multilamellar onion phases (the so-called vesicle phase) are often observed to be in equilibrium. [2] Since vesicles represent simple model systems for biological membranes and have practical applications (for example, for controlled drug or DNA release), [3] investigations of vesicle phases are of considerable interest in different areas, including surfactants, materials, and life sciences. Recently, two new self-assembled structures of controlled size (nanodisks and regular hollow icosahedra) were observed in dilute catanionic surfactants with H + and OH À counterions by Zemb and coworkers. [4][5][6] Such so-called "true" catanionic systems, with a nonswelling but finite uptake of water, and with a spacing of the same order as described in the current study were studied and documented by Jokela et al. [7] It was also later established by Rand, Parsegian, and Leiken [8] that the lamellar phase at maximum swelling of salt-free catanionic systems with a zero osmotic pressure, that is, the repulsive hydration interaction is compensated by van der Waals force at that point. The molar ratio r of the anionic to cationic components controls the structural surface charge and, hence, controls the long-range repulsive interaction independently of the weight volume fraction (f), which in turn controls the average colloidcolloid distance. The salt-free catanionic systems can be represented in a ternary phase diagram whose two independent variables are f and r.[6]Herein we report, for the first time to our knowledge, the discovery of a "true", salt-free concentrated catanionic uniand multilamellar onion phase that differs from the catanionic surfactant systems with excess salt that are formed by the combination of the counterions, as evident from our freezefracture transmission electron microscopy (FF-TEM) observations and small-angle X-ray scattering (SAXS) measurements. This molecular catanionic couple comprises the longest hydrocarbon chains described to date, so it was essential to determine if the carbon chains were in a frozen (gel) or liquid state. The size of the unilamellar vesicles ranges from about 20 to 700 nm and that of the large onions are several micrometers. The interlamellar spacing between the bilayers of onions is about 35 nm, thus suggesting rather compact packing of the bilayers. The high osmotic pressure sustains the highly stable colloidal suspension of the catanionic onion phase. The observations of the onion phase may prove valuable and stimulating to fellow specialists, not least as "true" catanionic surfactant systems do not seem to be exhaustively investigated yet.The "true" salt-free catanionic vesicle phase was obtained by mixing aqueous solutions of trimethyltetradecylammonium hydroxide (TTAOH) and oleic acid (OA; see Figure 3). The stock solution of TTAOH (pH 12-13) was prepared from the commercial bromide form (TTABr) by anion exchange with a strong b...

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“…[9] The critical micelle concentration (cmc) of TTAOH (0.0018 mol L À1 ) was determined by using surface tension measurements. The TTAOH stock solution was prepared from the TTABr solution (120 mm) by anion exchange with a strong base (Ion exchanger III, Merck) at 40 8C.…”

Section: Methodsmentioning

confidence: 99%

“…The molar ratio r of the anionic to cationic components controls the structural surface charge and, hence, controls the long-range repulsive interaction independently of the weight volume fraction (f), which in turn controls the average colloidcolloid distance. [9] The critical micelle concentration (cmc) of TTAOH was determined by surface tension measurements to be 1.8 mmol L À1 . This molecular catanionic couple comprises the longest hydrocarbon chains described to date, so it was essential to determine if the carbon chains were in a frozen (gel) or liquid state.…”

mentioning

confidence: 99%

An Onion Phase in Salt‐Free Zero‐Charged Catanionic Surfactant Solutions

Song¹,

Dong²,

Jia³

et al. 2005

View full text Add to dashboard Cite

Mixtures of cationic and anionic (catanionic) single-chain surfactants can readily form bilayers in aqueous solutions, [1] in which uni-and multilamellar onion phases (the so-called vesicle phase) are often observed to be in equilibrium. [2] Since vesicles represent simple model systems for biological membranes and have practical applications (for example, for controlled drug or DNA release), [3] investigations of vesicle phases are of considerable interest in different areas, including surfactants, materials, and life sciences. Recently, two new self-assembled structures of controlled size (nanodisks and regular hollow icosahedra) were observed in dilute catanionic surfactants with H + and OH À counterions by Zemb and coworkers. [4][5][6] Such so-called "true" catanionic systems, with a nonswelling but finite uptake of water, and with a spacing of the same order as described in the current study were studied and documented by Jokela et al. [7] It was also later established by Rand, Parsegian, and Leiken [8] that the lamellar phase at maximum swelling of salt-free catanionic systems with a zero osmotic pressure, that is, the repulsive hydration interaction is compensated by van der Waals force at that point. The molar ratio r of the anionic to cationic components controls the structural surface charge and, hence, controls the long-range repulsive interaction independently of the weight volume fraction (f), which in turn controls the average colloidcolloid distance. The salt-free catanionic systems can be represented in a ternary phase diagram whose two independent variables are f and r.[6]Herein we report, for the first time to our knowledge, the discovery of a "true", salt-free concentrated catanionic uniand multilamellar onion phase that differs from the catanionic surfactant systems with excess salt that are formed by the combination of the counterions, as evident from our freezefracture transmission electron microscopy (FF-TEM) observations and small-angle X-ray scattering (SAXS) measurements. This molecular catanionic couple comprises the longest hydrocarbon chains described to date, so it was essential to determine if the carbon chains were in a frozen (gel) or liquid state. The size of the unilamellar vesicles ranges from about 20 to 700 nm and that of the large onions are several micrometers. The interlamellar spacing between the bilayers of onions is about 35 nm, thus suggesting rather compact packing of the bilayers. The high osmotic pressure sustains the highly stable colloidal suspension of the catanionic onion phase. The observations of the onion phase may prove valuable and stimulating to fellow specialists, not least as "true" catanionic surfactant systems do not seem to be exhaustively investigated yet.The "true" salt-free catanionic vesicle phase was obtained by mixing aqueous solutions of trimethyltetradecylammonium hydroxide (TTAOH) and oleic acid (OA; see Figure 3). The stock solution of TTAOH (pH 12-13) was prepared from the commercial bromide form (TTABr) by anion exchange with a strong b...

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Current literature in mass spectrometry

2004

J. Mass Spectrom.

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In order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of mass spectrometry. Each bibliography is divided into 11 sections: 1 Books, Reviews & Symposia; 2 Instrumental Techniques & Methods; 3 Gas Phase Ion Chemistry; 4 Biology/Biochemistry: Amino Acids, Peptides & Proteins; Carbohydrates; Lipids; Nucleic Acids; 5 Pharmacology/Toxicology; 6 Natural Products; 7 Analysis of Organic Compounds; 8 Analysis of Inorganics/Organometallics; 9 Surface Analysis; 10 Environmental Analysis; 11 Elemental Analysis. Within each section, articles are listed in alphabetical order with respect to author (4 Weeks journals ‐ Search completed at 17th. Mar. 2004)

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Bromate assay in water by inductively coupled plasma mass spectrometry combined with solid-phase extraction cartridges

Cited by 14 publications

References 37 publications

An Onion Phase in Salt‐Free Zero‐Charged Catanionic Surfactant Solutions

An Onion Phase in Salt‐Free Zero‐Charged Catanionic Surfactant Solutions

An Onion Phase in Salt‐Free Zero‐Charged Catanionic Surfactant Solutions

Current literature in mass spectrometry

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