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.     

Photometric determination of quaternary ammonium compounds with hexanitrodiphenylamine. II

In strongly alkaline medium (more than 0.1 N NaOH) hexanitrodiphenylamine anion reacts with base. The reaction is rather slow and is partly reversible.Quaternary ammonium ions can be determined by extraction of their hexanitrodiphenylamine complexes with chloroform or methylene chloride at pH 11 or with methylene chloride from 3N NaOH. Only the latter method is applicable to compounds containing several quaternary ammonium groups. The compounds extracted have high molar extinction and good stability. Quaternary ammonium ions can be determined in the presence of amines, and in some cases determination of quaternary ammonium ions in admixture is possible.     

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.     

Understanding the Charge Issues in Mono and di-Quaternary Ammonium Compounds for Their Determination by LC/ESI-MS/MS

Chromatographers often develop problems while optimizing a method for the quantification of quaternary ammonium compounds in ESI-MS/MS. Intransigency observed in quaternary ammonium compounds to undergo the classical molecular adduct formation [M+H]⁺ in ESI-MS/MS reduces confidence among chromatographers while working with unit mass resolution. In this study, we provide the evidence for an exceptional rule followed by mono- and di-quaternary ammonium compounds in ESI-MS/MS in the precursor ion formation. Under ESI conditions mono- and di-quaternary ammonium compounds form molecular ions with the formula of m ^q / z ^q rather than ( m + z )/ z . Formation of m ^q / 2 is observed for di-quaternary ammonium compounds in precursor ion scan and m ^q / 1 in product ion scan, if loss of one of the quaternary charge occurs during CID. In di-quaternary ammonium compounds, this process can also result in the formation of fragment ions with higher mass as compared to precursor ion. Hydrophilic interaction liquid chromatographic separation has been used to demonstrate the elution of quaternary ammonium compounds in a single run in the ESI-MS/MS. This work concludes that the analyst must realize and consider these charge issues while dealing with positively charged compounds in LC/ESI-MS/MS.     

硫脲基咪唑啉季铵盐的合成及其缓蚀作用

用戊酸、羊蜡酸、油酸、二乙烯三胺、氯化苄和硫脲为原料,合成了6种咪唑啉季铵盐化合物。 采用静态失重法和极化曲线法,比较了硫脲基烷基咪唑啉型季铵盐和烷基咪唑啉型季铵盐在80 ℃、1 mol/L的HCl溶液中对碳钢的缓蚀性能,研究了这两类缓蚀剂与无机阴离子和阴离子表面活性剂的协同作用。 结果表明,硫脲基烷基咪唑啉季铵盐类的缓蚀效果明显优于烷基咪唑啉季铵盐类,硫脲基羊脂酸咪唑啉缓蚀剂的缓蚀率可达98.3%。 当以羊脂酸、二乙烯三胺、氯化苄和硫脲为原料合成的硫脲基烷基咪唑啉型季铵盐化合物与I-质量比为1∶1复配时,缓蚀效果最佳,比单独使用硫脲基烷基咪唑啉季铵盐化合物的缓蚀率提高了1.5%。     

Analysis of Quaternary Ammonium Compounds by Ion-Pair Thin Layer Chromatography on Silica Gel

Abstract

A general approach to the chromatographic analysis of quaternary ammonium compounds on silica gel thin layers is described. The quaternary cations migrate as ion pairs with bromide or iodide as counter ions. Methanol or chloroform-methanol mixtures serve as developing solvents, in which excess amounts of NaBr or NaI are dissolved. If the solvent cannot dissolve sufficient quantities of halide salts, the latter can be sprayed onto the plate as a methanol solution prior to development. The separation patterns of the quaternary ammonium compounds can be influenced by the choice of counter ion and by the choice of the organic solvent components.     

Hybrid nanocomposites based on guanidine methacrylate monomer and polymer and layered aluminosilicates: Synthesis, structure, and properties

Hybrid nanostructures (organomodified montmorillonite) have been synthesized on the basis of activated Na⁺-montmorillonite and new water-soluble ionogenic Na⁺-montmorillonite monomers containing quaternary ammonium guanidine cations. The structure and properties of poly(guanidine methacrylate) nanocomposites have been studied. It has been shown that these compounds efficiently adsorb heavy metals and exhibit a prolonged biocide effect due to the presence of quaternary ammonium guanidine cations.     

High-performance liquid chromatography on dynamically modified silica : III. Modification of silica with long-chain and symmetrical quarternary ammonium compounds

The influence of the nature of quaternary ammonium compounds on retention in high-performance liquid chromatography on dynamically modified silica was investigated. Adsorption isotherms were determined on bare silica (LiChrosorb Si 60) for four alkyltrimethylammonium bromides and two symmetrical tetraalkylammonium bromides, each containing 15–21 carbon atoms. It was found that only the long-chain quaternary ammonium ions are adsorbed on to the silica surface in appreciable amounts and that the affinity increasing number of carbon atoms in the alkyl chain. The maximum amount that can be adsorbed per gram of silica is of the same order of magnitude for each of the four long-chain quaternary ammonium compounds. This amount, however, is reached at lower concentrations in the eluent the longer is the alkyl chain.The retention of five test compounds was determined over the whole concentration range investigated for each of the modiflying agents. The surfactant concentration that causes maximum retention for four of five test compounds coincides with its critical micellar concentration. The retention mechanisms and the influence of the type of the modifying agent on selectivity are discussed, and compared with published results on related experiments on chemically bonded stationary phases.     

Ternary inclusion complexes of γ-cyclodextrin with sodium 1-pyrenesulfonate and cationic and anionic organic compounds having an alkyl chain in aqueous solution

The interactions of an organic anion, 1-pyrenesulfonate (PS), with γ-cyclodextrin (γ-CD) and organic cations such as quaternary ammonium compounds (or organic anions such as 1-decanesulfonate) have been examined by means of absorption and fluorescence spectroscopy. At a low concentration of PS, γ-CD forms a 1:1 inclusion complex with PS. PS forms organic cation–organic anion complexes with quaternary ammonium compounds. The organic cation–organic anion complexes of PS form ternary inclusion complexes with γ-CD. Equilibrium constants for the formation of these complexes have been evaluated from the fluorescence intensity change. As an alkyl chain in the quaternary ammonium compound is lengthened, the equilibrium constant for the formation of the ternary inclusion complex is increased. Although PS does not form complexes with organic anions such as 1-decanesulfonate, the organic anions are bound to the γ-CD cavity accommodating a PS molecule to form ternary inclusion complexes. However, the equilibrium constants for the organic anions (1-decanesulfonate etc.) are significantly less than those for the quaternary ammonium compounds. The small equilibrium constants for the organic anions can be ascribed to the electrostatic repulsion between PS and the organic anions.     

First colorimetric sensor array for the identification of quaternary ammonium salts

A colorimetric sensor array based on supramolecular host-guest complexes has been developed for the identification and quantification of quaternary ammonium salts (QAS). QAS are ubiquitous undesirable compounds for which the identification of the individual compounds is not trivial and needs instrumental techniques. The sensor array developed by us is constituted by host-guest complexes formed by the inclusion of tricyclic basic dyes such as proflavine, acridine orange, thionin, and methylene blue inside the hollow space defined by cucurbit[n]urils with n = 7 and 8. The operation of the sensor array has been demonstrated by differentiating 14 quaternary ammonium salts, some of them differing by a single carbon atom in the alkyl group. The detection limit concentration was 10⁻⁵ M and the system can also be used to quantify the concentration of the quaternary ammonium ion.     

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.     

Tetraethylammonium tetrafluoroborate: a novel electrolyte with a unique role in the capillary electrophoretic separation of polyphenols found in grape seed extracts

A capillary electrophoretic method for resolving phenolic compounds found in grape seed extracts was developed using a quaternary ammonium salt as the main electrolyte solution. Seven polyphenols were separated and identified. The separation mechanism seems to involve association between quaternary ammonium cations and the polyphenols. Migration times roughly correlate with the size of the known phenols. The role of the alkyl substituents on the quaternary ammonium ions was investigated and is discussed. The method of analysis proposed herein exhibits high reproducibility in terms of migration times for a complex mixture using a single component background electrolyte.     

Determination of alkyl benzyl and dialkyl dimethyl quaternary ammonium biocides in occupational hygiene and environmental media by liquid chromatography with electrospray ionisation mass spectrometry and tandem mass spectrometry

A new method for the simultaneous qualitative and quantitative determination of alkyl benzyl and dialkyl quaternary ammonium compounds (QACs) has been developed. Analysis is by reversed-phase high-performance liquid chromatography coupled with electrospray ionisation mass spectrometry. QACs are extremely amenable to the electrospray ionisation technique (limit of detection of BAC C12 homologue 3 ng ml(-1)). The selectivity of mass spectrometric detection allows simultaneous determination of benzyl and dialkyl dimethyl ammonium compounds. The method was successfully applied to the analysis of real samples (occupational hygiene sampling devices, products and swimming pool water). Structural information was obtained by MS-MS and cone voltage ion dissociation techniques. Ion dissociation enabled the structural elucidation of an unknown quaternary ammonium compound present in a commercial formulation.     

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.     

Quantitation of quaternary ammonium compounds using electrospray mass spectrometry

A sensitive and specific electrospray mass spectroscopic assay has been developed for the quantitation of the series of quaternary ammonium surfactant compounds dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, and octadecyltrimethylammonium bromide and neostigmine bromide. Standard solutions were prepared in methanol, with an appropriate quaternary ammonium internal standard used in each case, and injected into a carrier solvent comprising acetonitrile (99%) and methanol (1%). Detection was based upon the positively charged quaternary ammonium ion in each case. Using this new technique, significant increases in sensitivity have been obtained over more traditional gas chromatographic–mass spectroscopic analytical techniques. All of the compounds tested were readily quantifiable at solution concentrations of 50 ppb, with linear correlations (r²>0.995) obtained over the range 50–300 ppb for the alkyltrimethylammonium bromides, and 50–200 ppb for neostigmine bromide. It is envisaged that, using this method, adsorption isotherms for these compounds on highly adsorbing activated carbons should be readily acquired.     

芳氧亚甲基咪唑啉季铵盐的合成及缓蚀性能评价

合成了苯氧亚甲基咪唑啉季铵盐（POAI）和萘氧亚甲基咪唑啉季铵盐（NOAI）,通过失重法、电化学方法研究了二者在1 mol/L HCl中对A3钢的缓蚀性能,并对二者在A3钢表面的吸附行为进行了探讨。 结果表明,二者在1 mol/L HCl中对A3钢均有较好的缓蚀作用,其中NOAI对A3钢的缓蚀性能优于POAI的缓蚀性能;两化合物均为混合型缓蚀剂。 缓蚀性能随缓蚀剂浓度和温度的增大而增大;二者在A3钢表面的吸附过程吸热,是化学吸附,符合Langmuir吸附等温式。     

Synthesis and Properties of a New Class of Potential Biomedical Polymers

Both low molecular weight compounds and some polyelectrolytes containing quaternary nitrogen atoms in their structure have been known for some time to possess important biological activity. Aliphatic ammonium compounds are used as bacteriocides and muscle relaxants, and quinolinium compounds have recently been found to be excellent antileukemic agents. In addition, a considerable amount of evidence has been accumulated to show that organic ammonium salts combine with heparin, and the resulting complex may be used as a coating to render polymers blood-compatible. However, the introduction of ammonium groups into the backbone of a polymer exhibiting good mechanical properties offers certain advantages.     

2种癸二酸咪唑啉季铵盐的合成及缓蚀性能评价

合成了2种癸二酸咪唑啉季铵盐癸二酸-水杨酸咪唑啉季铵盐(SSAI)和癸二酸咪唑啉季铵盐(SAI),并采用失重法和电化学方法研究了这2种咪唑啉季铵盐对N80钢在1 mol/L HCl溶液中的缓蚀性能和吸附行为。 结果表明,在1 mol/L HCl溶液中这2种化合物对N80钢均有较好的缓蚀作用,缓蚀效率大小顺序为SSAI＞SAI。 SSAI和SAI均为混合偏阳极型缓蚀剂。 2种化合物在N80钢表面的吸附服从Langmuir吸附等温式,属于化学吸附。     

季鏻盐定域体制备阴离子膜电极的研究

本文合成了数种季鏻盐,并用于制成阴离子膜电极;比较了不同链长的季鏻盐和电活性物含量对电极性能的影响;研究了电极的电位选择性系数与阴离子性质的关系。     

Synthesis and properties of long-chain quaternary ammonium hydroxides

A series of long-chain quaternary ammonium hydroxides were synthesized from tertiary amines and confirmed by ~1H NMR and FTIR.Surface properties and pH of these surfactants were investigated.The critical micelle concentrations(CMC) of the synthesized quaternary ammonium hydroxides are lower than the conventional quaternary ammonium surfactants.The micelles shapes of these long-chain quaternary ammonium hydroxides in aqueous solution are spherical at a concentration of 0.1 mol/L.The pH values of the synthesized quaternary ammonium hydroxides are 12.25-12.51.