Substoichiometric determination of mercury with cetyltrimethylammonium bromide

A radiometric method based on substoichiometric isotope dilution analysis has been developed for the determination of mercury using cetyltrimethylammonium bromide (CTAB) as the substoichiometric reagent. The method is based on the extraction of mercury as an ionassociation complex of tetraiodomercurate(II) ion with a substoichiometric amount of CTAB in benzene. The calibration graph was found to be linear in the range 0–10 μg Hg (II) in the aqueous phase of 10 ml volume. A detection limit of 0.06 μg·ml⁻¹ could be achieved by the proposed method. The relative standard deviation of the method was found to be 3.0% and the method has been successfully applied to study the determination of mercury in various synthetic mixtures.     

Spectrophotometric determination of germanium with Catechol Violet and cetyltrimethylammonium bromide

A ternary complex between germanium, Catechol Violet (CV) and cetyltrimethylanunoniuni bromide is proposed for the determination of germanium. The stoichiometric ratio Ge:CV is 1:2. Beer's law is obeyed from 0.1 to 1.0 ppm of Ge. The method is highly selective. Interference from Sn(IV), Fe(III), Bi(III), Cr(VI), Mo(VI), V(V) and Sb(III) in mg amounts is eliminated by extracting the germanium into carbon tetrachloride from 9M HC1 and then stripping into water before the photometric determination.     

Spectrophotometric determination of thorium with Xylenol Orange and cetyltrimethylammonium bromide

The thorium-Xylenol Orange reaction sensitized by cetyltrimethylammonium bromide ( = 5.51 x 10(4) l.mole(-1).cm(-1)) is accompanied by a bathochromic shift from 570 to 600 nm. The system is more selective than the binary system, because the reaction pH is lowered from 4.0 to 2.5; Beer's law is obeyed for 0.04-4.00 ppm of thorium.     

Spectrophotometric determination of microamounts of scandium with o-chlorophenylfluorone and cetyltrimethylammonium bromide

The reaction of scandium(III) with o-chlorophenylfluorone (o-CIPF) in the presence of cetyltrimethylammonium bromide (CTMAB) has been studied. In an acetate buffer at pH 4.4, a red-purple complex is obtained, with maximum absorption at 569 nm and a molar absorptivity of 1.31 x 10(5)1.mole(-1).cm(-1). The composition of the complex is found to be 1:2:2 Sc-o-CIPF-CTMAB. Beer's law is obeyed over the range 0-12 mug/25 ml scandium. The proposed method has been used for determination of trace scandium in tungsten ores after its prior separation by solvent extraction.     

Physicochemical studies of the cetyltrimethylammonium bromide micellar system using a bromide selective electrode

The use of the bromide selective electrode in physicochemical studies of the cationic micellar system of cetyltrimethylammonium bromide (CTAB) is described. Potentiometric methods and appropriate equations have been developed and used to determine the critical micellar concentration, the ionization degree, and the apparent ion-exchange constants of various anions (fluoride, chloride, hydroxide, acetate, nitrate, sulfate and borate). The interaction of the cationic micelles of CTAB with various species [the lipophilic reagent 1-fluoro-2,4-dinitrobenzene, the anionic succinate and the cationic tris-(hydroxymethyl)-aminomethane] was monitored through the measurement of the changes in the concentration of the free bromide counterions.     

Spectrofluorimetric determination of niobium with morin enhanced by cetyltrimethylammonium bromide micelles

The effect of surfactants on the fluorescence of the niobium—morin system is described. Cationic surfactants strongly enhanced the intensity (e.g., cetyltrimethylammonium bromide (CTAB) gives an 80-fold increase), while anionic and non-ionic surfactants are without effect. The formation of 1:1 and 1:3 (Nb:morin) complexes is demonstrated spectrophotometrically. The conditional stability constants for these complexes in CTAB micelles are β₁ = (1.14 ± 0.01) × 10⁴ l mol^?1 amd β₃ = (5.66 ± 0.02 × 10¹⁰ l³ mol^?3. The micellar-enhanced fluorimetric method has a 1 μg l^?1 detection limit, and is highly selective. The r.s.d. for the determination of 50 μg l^?1 Nb is 3.5%.     

Spectrophotometric determination of molybdenum in steels with o-nitrophenylfluorone and cetyltrimethylammonium bromide

A method has been developed for determining microamounts of molybdenum(VI) in aqueous solution by means of the Mo-o-nitrophenylfluorone—cetyltrimethylammonium bromide system, in which micellar solubilization is applied. A red complex is formed in 0.2–0.6M hydrochloric acid medium. The sensitivity of the method is high, and the apparent molar absorptivity is 1.55 × 10⁵ l.mole⁻¹. cm⁻¹. The absorption peak of the complex appears at 530 nm. The colour of the complex develops quickly and is stable for more than 24 hr. The composition of the complex is Mo: o-NPF = 1:1, and the system obeys Beer's law in the range 0–10 μg of Mo per 25 ml. The method has been used for the rapid determination of molybdenum in alloy steels with satisfactory results.     

Ultrafiltration of cetyltrimethylammonium bromide solutions

Permeation data of cetyltrimethylammonium bromide (CTABr) in water by ultrafiltration (UF) through zircon membranes are reported as a first step in the knowledge of micellar enhanced ultrafiltration of heavy metals by cationic surfactants [1]. The experimental results are analysed using a model of diffusion in the membrane matrix based on the thermodynamics of irreversible processes (TIP). A comparison with the classical model of resistances in series indicates that these two approaches are consistent and that the TIP method leads to new insights into the observed resistances. The major insight relates to the understanding of the membrane resistance in terms of interactions membrane-permeants and permeants-permeants.     

Isotachophoretic separation of cetyltrimethylammonium bromide

Capillary isotachophoresis (ITP), equipped with the conductivity detection, was tested for the separation of cetyltrimethylamonium (CTMA) bromide. To prevent adsorption of CTMA to the capillary walls, several neutral polymers and ethanol were added into the leading electrolytes. Unlike polymer additives, the CTMA free monomers and micelles, created as a result of the isotachophoretic concentration effect, were recognised in the presence of ethanol from 10 to 25% (v/v). At 30% of ethanol, only a single zone of CTMA monomer was registered because the micellization process did not take place under this condition.Employing an ITP apparatus in the column-coupling configuration, the operational system with 30% of ethanol was tested for the determination of CTMA in hair conditioners. The achieved detection limits were about 0.02 mM. Both model solutions and real samples of hair conditioners were analysed with the precision about R.S.D. = 3%. One analysis in the column-coupled system takes circa 15 min.     

Spectrophtometric determination of tungsten(VI) with rutin and cetyltrimethylammonium bromide

Tungsten-(VI) reacts with rutin in the presence of cetyltrimethylammonium bromide to form a soluble yellow complex having maximum absorbance at 416 nm. The molar ratio of tungsten to rutin in the complex is 1:2. The molar absorptivity is 5.01 x 10(4) 1.mole(-1).cm(-1). Beer's law is obeyed over the range 1 x 10(-7)(-1) x 10(-5)M tungsten (VI). Optimum solution conditions for the determination of tungsten in various sample matrices have been found and the interference of diverse ions has been examined.     

Spectrophotometric determination of molybdenum with 7,8-dihydroxy-4-methylcoumarin and cetyltrimethylammonium bromide

The 1:2 complexes formed between molybdenum and 7,8-dihydroxy-4-methylcoumarin in the presence and absence of cetyltrimethylammonium bromide (CTAB) have been studied. The binary complex formed at pH 5.6-6.0 in the absence of CTAB exhibits an absortion maximum at 360 nm with a molar absorptivity of 5.1 x 10(4) 1.mole(-1).cm(-1). The complex formed at pH 4.8-6.0 in the presence of CTAB has a molar absorptivity of 1.32 x 10(5) 1.mole(-1).cm (-1) at 400 nm, the wavelength of maximum absorption. Optimum conditions for complex formation were investigated and a rapid, sensitive and relatively selective method for the determination of up to approximately 70% of Mo in diverse alloys and steels is described. Small amounts of zirconium and tungsten interfere.     

Anodic stripping voltammetric determination of titanium(IV) using a carbon paste electrode modified with cetyltrimethylammonium bromide

A method is described for the voltammetric determination of titanium(IV) using a carbon paste electrode modified in situ with cetyltrimethylammonium bromide. The cationic micellar surfactant adsorbs onto the electrode particularly at negative potentials, simultaneously preconcentrating titanium(IV) as the oxalate complex with reduction to titanium(III). Anodic stripping voltammetry exploiting reoxidation can be used for the determination of trace levels of titanium(IV). Linearity between current and concentration exists between 5 and 160 mug l(-1) Ti(IV) (preconcentration time 2 min). The limit of detection (calculated as 3sigma) is 0.1 mug l(-1), with a preconcentration time of 10 min.     

银纳米粒子共振光散射光谱法测定痕量CTMAB

利用十六烷基三甲基溴化铵(CTMAB)与银纳米粒子作用生成的聚集体,使体系的共振光散射(RLS)强度明显增强,建立了一种快速、简便的测定痕量CTMAB的RLS光谱法。考察了p H值,反应最佳时间,试剂加入顺序等因素对测定CTMAB的影响。实验结果表明,在p H值为10.88,作用时间为10 min,银纳米粒子浓度(以银原子计算)为2.5×10-3mol·L-1,按CTMAB、BR、银纳米粒子为添加顺序的条件下,测定CTMAB的线性范围为:5.0×10-9~5.0×10-7mol·L-1,检出限为3.8×10-9mol·L-1。该法用于合成样品中CTMAB的测定,灵敏度高,重现性好,结果准确。     

A sensitive electrochemical chlorophenols sensor based on nanocomposite of ZnSe quantum dots and cetyltrimethylammonium bromide

In this work, a very sensitive and simple electrochemical sensor for chlorophenols (CPs) based on a nanocomposite of cetyltrimethylammonium bromide (CTAB) and ZnSe quantum dots (ZnSe–CTAB) through electrostatic self-assembly technology was built for the first time. The composite of ZnSe–CTAB introduced a favorable access for the electron transfer and gave superior electrocatalytic activity for the oxidation of CPs than ZnSe QDs and CTAB alone. Differential pulse voltammetry (DPV) was used for the quantitative determination of the CPs including 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP) and pentachlorophenol (PCP). Under the optimum conditions, the peak currents of the CPs were proportional to their concentrations in the range from 0.02 to 10.0 μM for 2-CP, 0.006 to 9.0 μM for 2,4-DCP, and 0.06 to 8.0 for PCP. The detection limits were 0.008 μM for 2-CP, 0.002 μM for 2,4-DCP, and 0.01 μM for PCP, respectively. The method was successfully applied for the determination of CPs in waste water with satisfactory recoveries. This ZnSe–CTAB electrode system provides operational access to design environment-friendly CPs sensors.     

Adsorptive stripping voltammetric determination of cobalt in the presence of dimethylglyoxime and cetyltrimethylammonium bromide

A sensitive procedure for determination of micro-traces of Co(II) by adsorptive stripping voltammetry is proposed. The procedure exploits the enhancement of the cobalt peak obtained by use of the system Co(II)–dimethylglyoxime–piperazine-1,4-bis(2-ethanesulfonic acid)–cetyltrimethylammonium bromide. Using the optimized conditions, a detection limit (based on the 3 criterion) for Co(II) of 1.2×10^–11 mol L^–1 (0.7 ng L^–1) was achieved. The calibration plot for an accumulation time of 30 s was linear from 5×10^–11 to 4×10^–9 mol L^–1. The procedure was validated by analysis of certified reference materials and natural water samples.     

Spectrophotometric determination of traces of lead with bromopyrogallol red and cetyltrimethylammonium or cetylpyridinium bromide

A method is described based on the sensitizing effect of cetyltrimethylammonium or cetylpyridinium bromide on the lead-Bromopyrogallol Red colour reaction. The reaction is instantaneous and the colour remains stable for over 120 hr in the presence of Triton X-100. Both colour systems obey Beer's law up to 5.5 ppm of lead. Methods are described for dealing with interferences.     

Rapid determination of bromide in seawater samples by capillary ion chromatography using monolithic silica columns modified with cetyltrimethylammonium ion

Monolithic silica capillary columns dynamically modified with quaternary ammonium ions were evaluated for the determination of bromide in seawater samples. A quaternary ammonium ion such as cetyltrimethylammonium ion was dynamically introduced onto monolithic silica surfaces. The first layer of the modifier was introduced by electrostatic interaction, whereas the second layer was introduced by hydrophobic interaction. The latter layer worked as the anion-exchange sites. The modified monolithic silica capillary columns could be used for rapid separation of inorganic anions. Separation of authentic mixture of five anions was achieved within a few minutes. The addition of small amount of the modifier in the eluent improved the repeatability of the retention time. Seawater samples could be directly injected onto the prepared capillary columns, and bromide could be determined to be 63 mg/L.     

Potentiometric microtitration of anions with cetyltrimethylammonium bromide

Summary A new titrant, cetyltrimethylammonium bromide, has been evaluated for the potentiometric precipitation titration of small amounts of some large inorganic anions. Emf's were monitored with a fluoroborate ion-selective electrode and a double-junction reference electrode. The perchlorate, nitrate, and calcium electrodes also respond to the various anions. Sharp endpoint breaks were obtained for permanganate, hexafluoroarsenate, hexafluorophosphate, persulfate, tetrachloroplatinite, hexachloroplatinate, tetrachlorostannite, tetrachloroaurate, ferricyanide, tetrachloromercurate, tetrachlorothallate, hexachloroosmiate, and bismuth(III) in hydrochloric acid. Medium breaks were obtained for perrhenate, perchlorate, tetrafluoroborate, dichromate, hexafluoroantimonate, ferrocyanide, hexachlorostannate, and hexachloroiridate. Shallow breaks were obtained for iodide, periodate, and tetrachloropalladate. Because of the limited solubility of the titrant in water it cannot be used at concentrations higher than 0.01 N.

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Potentiometrische Mikrotitration von Anionen mit Cetyltrimethyl-ammoniumbromid. I

Zusammenfassung Cetyltrimethylammoniumbromid wurde als neues Titrationsmittel für die potentiometrische Fällungstitration kleiner Mengen großer anorganischer Anionen eingesetzt. Die EMK wurde mit einer ionenspezifischen Fluorboratelektrode und einer doppelt verbundenen Bezugselektrode gemessen. Perchlorat-, Nitrat- und Calciumelektroden eignen sich ebenfalls für die entsprechenden Anionen. Scharfe Endpunkte wurden erhalten für Permanganat, Hexafluoroarseniat, Hexafluorophosphat, Persulfat, Tetrachloroplatinit, Hexachloroplatinat, Tetrachlorostannit, Tetrachloroaurat, Eisen(Ill)cyanid, Tetrachloromercurat, Tetrachlorothallat, Hexachloroosmiat und Wismuth(III) in Salzsäure. Mittelscharfe Umschlagpunkte erhielt man für Perrhenat, Perchlorat, Tetrafluoroborat, Dichromat, Hexafluoroantimonat, Eisen(II)cyanid, Hexachlorostannat und Hexachloroiridat. Unscharfe Umschlagpunkte ergaben Jodid, Perjodat und Tetrachloropalladat. Wegen der begrenzten Löslichkeit des Titrationsmittels in Wasser kann es maximal in 0,01 N Lösung angewendet werden.

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Work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore Laboratory under contract number W-7405-ENG-48.

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This paper is dedicated to the memory of my mother, Flora Selig, who died in June 1979.     

Influence of cetyltrimethylammonium bromide on phosphatidylcholine-coated capillaries

Large unilamellar vesicles of egg-phosphatidylcholine (eggPC), a naturally occurring phospholipid, were used in capillary electrophoresis (CE) for semi-permanent coating of fused silica capillaries. The stability of the phospholipid coating was tested at different cetyltrimethylammonium bromide (CTAB) concentrations with and without CaCl₂ present in the coating solution. The effect of physical factors influencing the coating stability (e.g. duration of the coating time, storage temperature of the coating solution) were also studied. Standing overnight in background electrolyte (BGE) solution did not alter the eggPC phospholipid coating noticeably. The performance of the coating was tested with a mixture of basic proteins (lysozyme, ribonuclease A and -chymotrypsinogen A). Highest efficiencies (over 200,000 plates m^–1) were achieved when the capillary was filled for 15 h with a liposome solution containing both CTAB and CaCl₂.Electronic Supplementary Material Supplementary material is available for this article at     

Simultaneous determination of bromide and iodide ions by capillary isotachophoresis using quaternary ammonium salts

Bromide and iodide ions were determined simultaneously by capillary isotachophoresis using an aqueous electrolyte system; the separation principle was based on the ion-pairing equilibria between tetradecyldimethylbenzylammonium ion and these anions in the leading electrolyte. The interaction between iodide ion and tetradecyldimethylbenzylammonium ion was stronger than that for bromide ion. Thus complete separation of bromide and iodide ions could be obtained by using a leading electrolyte containing 1.5 mM tetradecyldimethylbenzylammonium ion. The pH of the leading electrolyte was adjusted to 5.0. The relative standard deviations of the zone length for bromide and iodide ions were 1.1 and 1.2%, respectively, when mixture of 3.0 mM of these ions was analysed. A 150-μl volume could be injected for the simultaneous determination of low concentrations of bromide and iodide ions.