in this study, a sensitive method of dispersive liquid phase microextraction based on ion-pair combined with the flame atomic absorption spectrometry was proposed for the determination of trace ni(ii) using aliquat 336-chloride as ion pair agent. several factors which have effect on  the microextraction efficiency of ni(ii), such as ph, extraction and dispersive solvent type and their volume, c...

phase together with a counterion. Schurig V (1984) Gas chromatographic separation of enantiomers on optically active stationary phases. Angewarde Chemie International Edition English 23: 747}765. Schurig V (1994) Enantiomer separation by gas chromatography on chiral stationary phases. Journal of Chromatography 666: 111}129. Schurig V and Nowotny H-P (1990) Gas chromatographic separation of enan...

We report in-situ spectroscopic measurements of the structure and orientation of molecules in the interfacial region between the semi-soluble ionic solid CaF2 (fluorite) and an aqueous phase. This paper integrates a series of new experiments with earlier results to give a comprehensive understanding of this very dynamic interface. We employ the surface specific technique, vibrational sum-freque...

The objective of this study was to investigate the impact of different hydrophobic ion pairs (HIP) on the oral bioavailability of the model drug octreotide in pigs. Octreotide was ion paired with the anionic surfactants deoxycholate, decanoate and docusate differing in lipophilicity. These hydrophobic ion pairs were incorporated in self-emulsifying drug delivery systems (SEDDS) based on BrijO10...

The influence of counterions on micellization of perfluorononanoic carboxylate ammonium salts in water and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF(4)) solutions was investigated by surface tension and (19)F NMR measurements and freeze-fracture transmission electron microscopy (FF-TEM) observations. Changes in the counterions of the fluorocarbon surfactants have different effects...

clonidine hydrochloride is an antihypertensive agent used for migraine prophylaxis, attention deficit hyperactivity disorder, menopausal flushing and tourette syndrome. the quantity of the active substance in pharmaceutical preparations must be within specific limits, in agreement with the respective label claim. therefore, the aim of this study was to establish the conditions for two spectroph...

We describe positive interference with the ion-selective electrode determination of lithium (Lytening 2Z analyzer; Dade) when blood is collected in a 10-mL plain red-top plastic Vacutainer Plus Tube (Becton Dickinson) containing a silica clot activator and silicone surfactant (prod. no. 36-7820). We evaluated both the original tube (blue-labeled) and a new tube formulated to contain less silico...

the ability of natural clinoptilolite and its modified forms were studied for removal of pahs from n-paraffin. surfactant modified zeolite (smz) was obtained by modifying clinoptilolite with hexadecyltrimethylammonium ion. homoionic forms of zeolite were obtained by ion exchange process using inorganic salts of desirable cations (e.g. ag+, fe3+…). natural clinoptilolite and its cation exchanged...