Development and Validation of a Capillary Electrophoresis Method for the Determination of Denatonium Benzoate in Denaturated Alcohol Formulations

Capillary electrophoretic (CE) technique was investigated for the rapid analysis of denatonium benzoate (Bitrex), a quaternary ammonium salt, in several denaturated alcohol formulations. The optimized separations were carried out in 0.025 mol L^–1 Tris-phosphate electrolyte (pH 7.0) using direct UV detection at 214 nm. In order to prevent precipitation of hydrophobic matrix components in aqueous electrolyte, an electrokinetic sample introduction mode with internal standard (triethylbenzylammonium chloride) was used. Valid calibration (r²=0.998) was demonstrated in the range 2-50 mg L^–1 of Bitrex. The detection limit determined for 10 s electrokinetic (5 kV) injection was 0.45 mg L^–1 (three times the baseline noise). The proposed method was applied to the determination of Bitrex in various Lithuanian denaturated alcohol formulations and the results were statistically comparable with those obtained by HPLC technique.     

组合化学法筛选聚苯乙烯固载季铵盐相转移催化剂研究(I)

利用组合化学方法合成了一个含有60种不同结构的聚苯乙烯固载季铵盐相转移催化剂的催化剂库,以有外加碱条件下亲核取代反应为探针反应,利用迭代法从中筛选出了活性最高的催化剂,建立了一种快速合成和筛选聚苯乙烯固载季铵盐相转移催化剂的方法。     

Detection of Quaternary Ammonium Drugs in Equine Urine by Liquid Chromatography-Mass Spectrometry

Quaternary ammonium drugs are anticholinergic agents and some of which have been known to be abused in equine sports. A general screening method for this class of drugs in equine urine by liquid chromatography-mass spectrometry (LC-MS) has not been reported. The paper describes an efficient LC-MS-MS method for the simultaneous detection and confirmation of twenty quaternary ammonium drugs at low ng mL^?1 in equine urine after solid-phase extraction. Quaternary ammonium drugs were extracted from equine urine by solid-phase extraction using ISOLUTE^® CBA SPE Columns and analysed by LC-MS-MS in the positive electrospray ionisation mode. Separation of twenty quaternary ammonium drugs (the quaternary ammonium ions of edrophonium chloride, pyridostigmine bromide, neostigmine bromide, bretylium tosylate, ipratropium bromide, tubocurarine chloride, N-butylscopolammonium bromide, mepenzolate bromide, rocuronium bromide, clidinium bromide, pipenzolate bromide, isopropamide iodide, glycopyrronium bromide, alcuronium chloride, oxyphenonium bromide, propantheline bromide, tridihexethyl chloride, vecuronium bromide, mivacurium chloride and pancuronium bromide) was achieved in a reversed phase column with a mixture of aqueous ammonium formate (pH 3.0, 10 mM) and acetonitrile as the mobile phase. Detection and confirmation of the twenty quaternary ammonium drugs at about 5 ng mL^?1 in equine urine could be achieved within 22 min using product-ion scan MS-MS. The target analytes were detected by examination of extracted-ion chromatograms of their product ions. Drugs spiked in different equine urine (n = 15) were consistently detected. Negative samples (n = 30) of normal post-race equine urine have also been analysed, no matrix interference at the targeted masses and retention times was observed. The method was successfully applied to the analyses of drug-administration samples. Other method validation data including reproducibility and recovery will also be presented. An LC-MS-MS method for the simultaneous detection and confirmation of twenty quaternary ammonium drugs in equine urine was developed. The methodology should be applicable to other biological matrices such as human urine.     

Study of a novel cationic calix[4]arene used a selectivity modifier in capillary electrophoresis with electrochemical detection

The use of a novel cationic calixarene, p-(quaternary ammonium) calix[4]arene, as selectivity modifier in capillary electrophoresis coupled with electrochemical detection was reported. The calixarene displayed good selectivity for the positional isomers of benzenediol and aminophenol and their successful separation was obtained under optimum conditions. The interaction mechanism between p-(quaternary ammonium) calix[4]arene and the solutes is discussed using the molecular modeling method. The detection limits by electrochemical detection for the most solutes studied here were below picogram level, which was 2 orders of magnitude lower than those reported in the literature using UV detection. The results showed that electrochemical detection is especially suitable for an electrophoresis system where calixarenes are used as modifier.     

Electrochemically initiated polymerization of styrene with tetraalkyl and -aryl group VA halide support electrolytes

The electrochemically initiated polymerization of styrene in methylene chloride solvent with the use of platinum electrodes and tetraalkyl and -aryl group VA halides (i.e., quaternary ammonium, phosphonium, and arsonium compounds) as electrolyte has been investigated. The order of reactivity of the electrolytes with respect to polymerization rate and initiation efficiency was found to be: arsonium > phosphonium > ammonium. Mechanisms involving the electroreduction of the group VA quaternary halides to species capable of electroinitiating polymerization are postulated. The observed losses in solution conductivities during polymerization with the quaternary phosphonium and arsonium electrolytes indicate possible interaction between the initiating radical-ionic species and the supporting electrolyte. In an attempt to further elucidate the mechanism of initiation in these systems, a separate series of experiments, employing the nonpolymerizing monomer, 1,1-diphenylethylene, has been carried out.     

N-甲基-N-丁基吡咯烷溴化物和N-甲基-N-乙基吡咯烷溴化物在锌溴液流电池中应用

在锌溴液流电池中,作为溴络合剂在电解液中使用的季铵盐对电池性能及安全性具有重要作用.本文利用循环伏安法及线性扫描伏安法研究了N-甲基-N-丁基吡咯烷溴化物（N-methyl-N-butyl-pyrrolidinium bromide,MBP）和N-甲基-N-乙基吡咯烷溴化物（N-methyl-N-ethyl-pyrrolidinium bromide,MEP）分别加入到电解液后对电极反应的影响,通过交流阻抗（EIS）的方式测量了不同组成及浓度下的电解液电导率变化,测试了不同电解液对电池充放电性能的影响及溴络合能力,结果表明加入MBP的电解液具有更好的溴络合能力和电池性能.     

Determination of potassium in sea-water by capillary isotachophoresis

Summary A new analytical procedure for the determination of potassium in sea-water was developed using capillary isotachophoresis and ion-exchange. After the sea-water sample was passed through the column packed with an ammonium form cation-exchange resin, sodium ion was removed with 2×10^–2 mol/l ammonium chloride solution and then potassium ion was eluted with 3×10^–1 mol/l ammonium chloride solution. Simultaneous determination of potassium and sodium ions was performed with a newly developed electrolyte system; the leading electrolyte was 5 mmol/l cesium hydroxide containing 2 mmol/l 18-crown-6, 0.01% hydroxypropyl methylcellulose (HPMC) and 70% methanol; the terminating electrolyte was 5 mmol/l tetrabutylammonium bromide containing 0.01% HPMC and 70% methanol. A large amount of ammonium in the eluate did not interfere with the isotachophoretic measurement of potassium and sodium ions. A linear working curve was obtained for artificial sea-water samples containing up to 700 mg/l potassium ion. The proposed method was applied to the determination of potassium in surface and bottom sea-water samples.

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Kaliumbestimmung in Meereswasser durch Capillar-Isotachophorese

     

Synthesis of a novel series of polymerizable surfactants and application in emulsion polymerization

A series of polymerization surfactants (surfmers) was synthesized, whose structures combined the characteristics of polyoxyethylene as nonionic group and quaternary ammonium a as cationic group. The structures of the product were confirmed by MS, and the content of cationic‐activity matter was determined by two‐phase titration. The surfmers were then used with constant addition profiles in semicontinuous polymerization of vinyl acetate–butyl acrylate–Veova 10–hexafluorobutyl methacrylate, and the polydispersity indexes (PDI) were lower than 0.1. The particle size, amount of coagulum, and stability against electrolyte and freeze/thaw were evaluated. As a reference, an unreactive surfactant cetyl trimethyl ammonium bromide (CTAB) was also used for the polymerization. Compared to CTAB, the surfmers behaved much better. Not only stabilities to electrolyte and water resistance were improved, but also freeze/thaw stability got a superior performance. Copyright © 2008 John Wiley & Sons, Ltd.     

弱酸强碱两性树脂吸附盐的平衡研究

本文采用静态吸附法研究了各种盐溶液在弱酸强碱两性树脂上的吸附平衡规律，证明了其满足 Ｌａｎｇｍｕｉｒ的吸附等温线方程，并从该方程中的 ｂ值推断出各种离子对两性树脂的选择性顺序以及破坏内盐键的能力大小。     

Simultaneous two- and three-component determinations in multicomponent mixtures by extraction-spectrophotometry and thermochromism of ion-association complexes

A selective method of determination of amines and quaternary ammonium salts by solvent extraction and thermochromism of ion-association complexes has been established. The method is based on the formation of ion-association species with tetrabromophenolphthalein ethyl ester and the thermochromism effect in the organic phase at low temperature. The absorbance of the red amine charge-transfer complexes decreases quantitatively (DeltaA) with increase in temperature (DeltaT), and Delta A Delta T is characteristic of a particular species. This characteristic has been applied for the sensitive and selective determination of amines. The absorbance of the blue quaternary ammonium ion-association complexes does not vary with temperature, however, and the quaternary ammonium compounds can be determined without interference by amines because of the disappearance of the red species at 60 degrees . Methylephedrine, diphenhydramine, ephedrine (amines), benzethonium and/or berberine (quaternary ammonium compounds) in two- and three-component mixtures can be determined by using the thermochromism effect. The method is highly selective, sensitive and reproducible.     

Chromatographic retention behaviour, modelling and separation optimisation of the quaternary ammonium salt isometamidium chloride and related compounds on a range of reversed-phase liquid chromatographic stationary phases

This paper describes the reversed-phase liquid chromatographic behaviour of the trypanocidal quaternary ammonium salt isometamidium chloride and its related compounds on a range of liquid chromatographic phases possessing alkyl and phenyl ligands on the same inert silica. In a parallel study with various extended polar selectivity phases which possessed different hydrophobic/silanophilic (hydrogen bonding) activity ratios, the chromatographic retention/selectivities of the quaternary ammonium salts was shown to be due to a co-operative mechanism between hydrophobic and silanophilic interactions. The highly aromatic and planar isometamidium compounds were found to be substantially retained on stationary phases containing aromatic functionality via strong π-π interactions. The chemometric approach of principal component analysis was used to characterise the chromatographic behaviour of the isometamidium compounds on the differing phases and to help identify the dominant retention mechanism(s). Two-dimensional (temperature/gradient) retention modelling was employed to develop and optimise a rapid liquid chromatography method for the separation of the six quaternary ammonium salts within 2.5 min which would be suitable for bioanalysis using liquid chromatography-mass spectrometry. This is the first reported systematic study of the relationship between stationary phase chemistries and retention/selectivity for a group of quaternary ammonium salts.     

Thin-film microextraction coupled to LC-ESI-MS/MS for determination of quaternary ammonium compounds in water samples

The dual nature of the quaternary ammonium compounds, having permanently charged hydrophilic quaternary ammonium heads and long-chain hydrophobic tails, makes the sample preparation step and analysis of these compounds challenging. A high-throughput method based on thin-film solid-phase microextraction (SPME) and liquid chromatography mass spectrometry was developed for simultaneous quantitative analysis of nine benzylic and aliphatic quaternary ammonium compounds. Chromatographic separation and detection of analytes were obtained in reverse-phase mode in 8 min using a triple quadrupole mass spectrometer. Hydrophilic lipophilic balance particle-coated blades were found to be the most suitable among the different coatings tested in terms of recoveries and carryover on the blades. For desorption solvents, 70/30, v/v (A/B) with 0.1 % formic acid (where A is 10 mM ammonium acetate in acetonitrile/water (95/5?, v/v) and B is 0.1 %? (v/v) formic acid in isopropyl alcohol) was shown to be the most efficient solvent for the desorption of the analytes from the SPME sorbent. The SPME method was optimised in terms of extraction, pH, and preconditioning, as well as extraction and desorption times. Optimum conditions were 45 min of extraction time and 15 min of desorption time, all with agitation. The extraction was found to be optimum in a range of pH 6.0 to 8.0, which is consistent with the natural pH of water samples. Wide linear dynamic ranges with the developed method were obtained for each compound, enabling the application of the method for a wide range of concentrations. The developed method was validated according to the Food and Drug Administration criteria. The proposed method is the first SPME-based approach describing the applicability of the high-throughput thin-film SPME in a 96-well system for analysis of such challenging compounds.     

Capillary electrochromatography with monolithic stationary phases. II. Preparation of cationic stearyl-acrylate monoliths and their electrochromatographic characterization

A novel cationic monolithic stationary phase based on the co-polymerization of pentaerythritol diacrylate monostearate (PEDAS) with a selected quaternary amine acrylic monomer was designed for performing capillary electrochromatography at high flow velocity. While PEDAS functioned as both the ligand provider and the cross-linker, the quaternary amine acrylic monomer was introduced to control the magnitude of the electroosmotic flow (EOF). The fabrication of the cationic stearyl-acrylate monolith (designated as cationic C17 monolith) with controlled porosity was achieved by free radical polymerization using the initiator 2,2'-azobisisobutyronitrile in the presence of a ternary porogenic solvent composed of cyclohexanol, ethylene glycol and water. Four different quaternary amine acrylic monomers were investigated in order to find the optimum monomer for achieving maximum electroosmotic flow (EOF) velocity. Both photo- and thermally-initiated polymerization proved effective in producing the cationic C17 monolith, and the best monolith was achieved when [2-(acryloyloxy)ethyl]trimethyl ammonium methyl sulfate (AETA) was used as the quaternary amine acrylic monomer. Although the zeta potential of the resulting cationic C17 monolith is positive with respect to water, the magnitude and direction of the EOF was markedly affected by the nature of the electrolyte in the mobile phase. Consequently, anodal, zero or cathodal EOF was observed depending on the nature of the electrolyte, and this was attributed to the adsorption of the ionic components of the electrolyte on to the solid stationary phase, which is characterized by its amphiphilic nature consisting of C17 chains, ester functions, hydroxyl groups and quaternary amine moieties. Optimized PEDAS-AETA monoliths yielded columns with high separation efficiency and allowed rapid separations on the time scale of seconds to be achieved with short capillaries.     

Mixed ternary ion associate formation between xanthene dye, cinchona-alkaloid and quaternary ammonium ion and its application to the determination of trace amounts of quaternary ammonium salts in pharmaceuticals

Xanthene dyes such as eosin and tetraiodofluorescein form 1:2 ion associates with quaternary ammonium ions at pH 7-9; however, the development of color in the organic solvent is poor. When a quaternary ammonium salt is added in the extractable 1:2 associate formed between a xanthene dye and a cinchona-alkaloid in the neutral media, a mixed ternary ion associate (xanthene dye:cinchona-alkaloid:quaternary ammonium ion=1:1:1) is formed. Its extractability is enhanced due to the more bulky associate formation. The ion association caused by addition of cinchona-alkaloids is unique. Of the cinchona-alkaloids, quinidine and cinchonidine with tetraiodofluorescein show excellent effects on sensitivity and extractability. Eosin and tetraiodofluorescein are useful as ion association reagents in the ion associate formation. The apparent molar absorptivities are about 1×10⁵ l mol⁻¹ cm⁻¹ and the calibration range for quaternary ammonium salt is from 2.5×10⁻⁷ to 1.5×10⁻⁶ M. The proposed method is applicable to the selective and sensitive determination of cetylpyridinium chloride, berberine chloride and benzethonium chloride in pharmaceuticals.     

Redox monomer ionic liquid based on quaternary ammonium: From electrochemistry to polymer brushes

Bifunctional quaternary ammonium ionic liquid bearing redox and polymerisable units was synthesized. The electrochemical investigations of the ferrocene monomer ionic liquid were performed. Following that, surface-initiated atom transfer radical polymerization (SI-ATRP) was used to build polymer brushes onto the electrode surface. The presence of the Poly(ferrocenyl quaternary ammonium) was evidenced by surface and electrochemical analysis. The latter exhibits high electron transfer rate and the presence of ions within the polymer framework leads to record the attached ferrocenyl redox signal in solution without adding supporting electrolyte. Finally, the wettability of the surface was modulated by electrochemical switch and by anion exchange within the polymer.     

新型二茂铁甲基季铵盐离子液体的合成与表征

以二茂铁与二甲胺为原料合成了碘化二茂铁甲基季铵盐,再经复分解反应得到乙酸二茂铁甲基季铵盐离子液体;表征了离子液体的结构,测定了其熔点和溶解性.结果表明,合成的乙酸二茂铁甲基季铵盐离子化合物熔点低于100℃,是一种新型的二茂铁甲基季铵盐离子液体.     

Dynamic behavior of potentiometric ammonia-sensing probes in samples of high osmolarity

Results are presented for potentiometric ammonia gas-sensors which show that the response times increase significantly with age of the sensor when ammonium picrate is used as internal electrolyte and the samples have greater osmolarities than the internal electrolyte solution. A build-up of ammonium picrate crystals on the inner side of the gas-permeable membrane is responsible for this increasein response time. The use of ammonium chloride as internal electrolyte provides constant response times indepent of sample osmotic strength, and is recommended as a means of ensuring that optimal dynamic response characteristics are maintained.     

Determination of diethanolamine or <Emphasis Type="Italic">N</Emphasis>-methyldiethanolamine in high ammonium concentration matrices by capillary electrophoresis with indirect UV detection: application to the analysis of refinery process waters

Alkanolamines such as diethanolamine (DEA) and N-methyldiethanolamine (MDEA) are used in desulfurization processes in crude oil refineries. These compounds may be found in process waters following an accidental contamination. The analysis of alkanolamines in refinery process waters is very difficult due to the high ammonium concentration of the samples. This paper describes a method for the determination of DEA in high ammonium concentration refinery process waters by using capillary electrophoresis (CE) with indirect UV detection. The same method can be used for the determination of MDEA. Best results were achieved with a background electrolyte (BGE) comprising 10 mM histidine adjusted to pH 5.0 with acetic acid. The development of this electrolyte and the analytical performances are discussed. The quantification was performed by using internal standardization, by which triethanolamine (TEA) was used as internal standard. A matrix effect due to the high ammonium content has been highlighted and standard addition was therefore used. The developed method was characterized in terms of repeatability of migration times and corrected peak areas, linearity, and accuracy. Limits of detection (LODs) and quantification (LOQs) obtained were 0.2 and 0.7 ppm, respectively. The CE method was applied to the determination of DEA or MDEA in refinery process waters spiked with known amounts of analytes and it gave excellent results, since uncertainties obtained were 8 and 5%, respectively.     

The analysis of aliquat-336 by gas chromatography

The determination of the quaternary ammonium components of Aliquat-336 by gas chromatography using tetraheptylammonium chloride as an internal standard is described. The method relies on the fact that long-chain quaternary ammonium salts undergo thermal decomposition at high injection port temperatures to form tertiary amines. The major component in Aliquat-336 is methyldioctyldecylammonium chloride with up to four other quaternary ammonium compounds being present. Aliquat-336 also contains 1-octanol and 1-decanol and some water.     

Palladium‐catalyzed carbonylation of quaternary ammonium halides to tertiary amides

Catalytic carbonylation of quaternary ammonium salts under anhydrous conditions was investigated using palladium catalyst. The carbonylation of tetramethylammonium iodide was chosen as a model reaction and studied systematically. Ligand‐free PdCl₂ showed efficient catalytic performance for this transformation. A palladium catalyst loading as low as 0.05 mol% was sufficient for high yield (96.9%) of N,N‐dimethylacetamide, corresponding to a turnover frequency of 242 h^?1. Under optimum conditions, several other quaternary ammonium halides were also carbonylated to corresponding tertiary amides in moderate to excellent yields. The catalytic activity of commercial palladium on activated carbon (Pd/C) catalyst was also evaluated. The Pd/C catalyst exhibited high activity for this carbonylation reaction and could be recycled six times with a slight decrease in activity. Furthermore, mechanistic considerations concerning Pd‐catalyzed carbonylation of quaternary ammonium halides were also discussed. Copyright © 2014 John Wiley & Sons, Ltd.