Search results for "ethylamine"
showing 10 items of 230 documents
Automated on-line in-tube solid-phase microextraction-assisted derivatization coupled to liquid chromatography for quantifying residual dimethylamine…
2008
Abstract A method for the analysis of dimethylamine (DMA) by automated in-tube solid-phase microextraction (IT-SPME)-supported chemical derivatization coupled with high-performance liquid chromatography was developed. Extraction, derivatization and desorption were studied by using a capillary coated with 95% polydimethylsiloxane and 5% polydiphenylsiloxane. Solution derivatization and automated IT-SPME derivatization using 9-fluorenylmethyl chloroformate (FMOC) were compared. The proposed procedure provided adequate linearity, accuracy and precision in the 0.2–2.0 μg/mL concentration interval, and the limit of detection (LOD) was 50 ng/mL. The main advantages of the proposed procedure are: …
Liquid chromatographic determination of trimethylamine in water.
2004
A method for the selective determination of trimethylamine (TMA) in aqueous matrices by liquid chromatography is reported. The proposed procedure is based on the derivatization of the analyte with 9-fluorenylmethyl chloroformate (FMOC) in a precolumn (Hypersil C18, 30 microm, 20 mm x 2.1 mm i.d.) connected on-line to the analytical column (LiChrosphere 100 RP18, 5 microm, 125 mm x 4 mm i.d.). Gradient elution was performed with a mixture of acetonitrile-water-0.05 M borate buffer (pH 9.0). The method has been applied to the direct determination of TMA in water within the 0.25-10.0 microg/ml concentration interval, and can also be adapted to the determination of TMA over the range 0.05-1.0 m…
Automated trace enrichment for screening and/or determination of primary, secondary and tertiary amphetamines in biological samples by liquid chromat…
1999
A rapid and simple liquid chromatographic method for the automated determination of amphetamines in biological fluids was developed. The proposed procedure is based on the injection of 250 microL of sample into a 20 x 2.1 mm id precolumn (packed with a 30 microns Hypersil C18 stationary phase) for enrichment and purification of the analytes. Next, the analytes are transferred to a 5 microns LiChrospher 100 RP18, 125 x 4 mm id analytical column for their separation under reversed-phase conditions. Water was used to eliminate the matrix components from the precolumn and a 0.2 M phosphate buffer (pH 3) containing 2% triethylamine was the mobile phase for the resolution of the amphetamines. The…
Comparative study of the determination of trimethylamine in water and air by combining liquid chromatography and solid-phase microextraction with on-…
2005
This work describes a new approach for the determination of trimethylamine (TMA) in water and air by liquid chromatography (LC). The assay is based on the employment of a solid-phase microextraction (SPME) fiber for sampling and for derivatization of the analyte with the fluorogenic reagent 9-fluorenylmethyl chloroformate (FMOC). The fiber, with a Carbowax-templated resin -50mum coating, was first immersed into a solution of the reagent. Once loaded with the reagent, the fiber was immersed into the water samples or exposed to the air samples in order to extract and to derivatize the analyte. Finally, the fiber was placed into a HPLC-SPME interface to desorb and transfer the TMA-FMOC derivat…
Deprotonation of resorcinarenes by mono- and diamine bases: complexation and intermolecular interactions in the solid state
2014
The deprotonation of resorcinarenes by mono- and dibasic amines, viz. triethylamine (TEA) and its dibasic analogue, N,N′-dimethylpiperazine (DMPip), was studied and the resulting supramolecular complexes were analysed in the solid state, in solution and in the gas phase. In the solid state, 1:1 (2TEAH+·(ethyl-resorcinarene)2−·MeOH), 3:2 [DMPip·2DMPipH+·2(ethyl-resorcinarene−)] and 3:2 [2DMPip·DMPipH22+@(2methyl-ethyl-resorcinarene−)2·2MeOH] solid state complexes and interesting resorcinarene−⋯resorcinarene− supramolecular networks formed via enhanced hydrogen bonds involving the hydroxyl groups and the deprotonated hydroxyl groups of the resorcinarenes were observed. The host–guest complexe…
A method for the determination of dimethylamine in air by collection on solid support sorbent with subsequent derivatization and spectrophotometric a…
2005
A new method for dimethylamine determination in air is reported. The proposed assay is based on the employment of C18-packed solid phase extraction cartridges for sampling. The retained amine is then derivatized inside the cartridges with the reagent 1,2-naphthoquinone-4-sulfonate. By observing the coloured area of the cartridge, a semiquantitative estimation of the amine can be made. It was also possible to distinguish between primary and secondary amines by visual inspection. Quantitative tests entailed desorption from the cartridges of the derivatives formed, and measurement of the absorbance of the collected extracts. The selected conditions were applied to quantify dimethylamine up to …
Sensitive determination of aliphatic amines in water by high-performance liquid chromatography with chemiluminescence detection.
2004
A sensitive method has been developed for liquid chromatographic determination of short aliphatic amines in water samples. Analytes are preconcentrated and dansylated on solid sorbents (C18 solid-phase extraction cartridges). The dansyl derivatives are chromatographed and post-column mixed with peroxyoxalate (TCPO) and H2O2 in order to perform chemiluminescence detection. Optimal results have been obtained using a sample volume of 5 ml. The method has been applied to the quantification or screening of several aliphatic amines: methylamine, ethylamine, butylamine, diethylamine, pentylamine and hexylamine. The screening procedure has been developed including also polyamines (putrescine, cadav…
Derivatization of amines in solid-phase extraction supports with 9-fluorenylmethyl chloroformate for liquid chromatography
1997
Abstract A new method based on reaction in solid-phase extraction cartridges with 9-fluorenylmethyl chloroformate is described for improved derivatization of amines prior to liquid chromatography. The effects of the reaction conditions, the kinetics of the reaction and the kind of packing material on the derivatization have been evaluated. The reliability of the described approach has been tested by derivatizing propylamine, diethylamine, diethanolamine, glycine, glutamic acid, p-aminobenzoic acid and β-phenylethylamine. Reaction yields compared with those of the analogous solution derivatizations were in the 44–169% range, and satisfactory linearity was achieved at concentrations of the am…
Rational synthetic design of well-defined Pt(bisethynyl)/Zn(porphyrin) oligomers for potential applications in photonics
2011
Well-defined oligomers of 1, 2, 3 and 4 units built upon the very soluble bis-1,15-(1,4-ethynylbenzene)-3,7,13,17-tetramethyl-2,8,12,18-tetrakis(n-hexyl) zinc(II) porphyrin ligand and the trans-bis(tri-n-butylphosphine)platinum(II) linker, with acetylene or trimethylsilane as end groups, has been prepared in the presence of a dichloromethane/diethylamine mixture (1 : 1 v/v) and CuX (X = Cl, I) at room temperature, analogue to a Sonogashira coupling. The new monodisperse organometallic oligomers were characterized by 1H, 31P NMR, UV-visible spectroscopies and MALDI-TOF mass spectrometry. The methyl groups placed at the 3,7,13,17-positions induces the locking of the C6H4 fragment in a perpend…
A Convenient Generation of Acetic Acid Dianion
2003
The lithium enediolate of acetic acid can be generated efficiently, as a 0.5 M solution in THF, using lithium amides prepared from n-butyllithium in THF and either diethylamine or 1,3,3-trimethyl-6-azabicyclo-(3.2.1)-octane (AZA). Its reaction with carbonyl compounds leads to the corresponding β-hydroxy acids in good to moderate yields. Better yields are usually obtained when these amines are added in sub-stoichiometric amounts. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)