Search results for "Capillary Action"
showing 10 items of 179 documents
Immunochromatographic Assay for Quantitation of Milk Progesterone.
1996
We describe a rapid immunochromatographic method for the quantitation of progesterone in bovine milk. The method is based on a 'competitive' assay format using the monoclonal antibody to progesterone and a progesterone-protein conjugate labelled with colloidal gold particles. The monoclonal antibody to progesterone is immobilized as a narrow detection zone on a porous membrane. The sample is mixed with colloidal gold particles coated with progesterone-protein conjugate, and the mixture is allowed to migrate past the detection zone. Migration is facilitated by capillary forces. The amount of labelled progesterone-protein conjugate bound to the detection zone, as detected by photometric scann…
On-line removal of mass interferences in palladium determination by ICP-MS using modified capillaries coupled to micro-flow nebulizers
2001
This paper describes a novel approach developed for on-line removal of interferences within modified capillaries coupled to micro-flow nebulizers, for palladium determination by inductively coupled plasma mass spectrometry (ICP-MS). A strong cation exchanger [2-(4-chlorosulfophenyl)ethyltrichlorosilane)] was covalently bound to the silica capillary that was coupled to a microconcentric nebulizer (MCN) or to a direct injection nebulizer (DIN). The modified surface of the capillary was able to selectively retain copper and yttrium from aqueous samples at pH 7.5 during the sample introduction step, while Pd was not retained and 105Pd could be determined in the absence of interferent elements. …
Automatic in-tube SPME and fast liquid chromatography: A cost-effective method for the estimation of dibuthyl and di-2-ethylhexyl phthalates in envir…
2007
A 80-cm length commercially available capillary coated with 95% polydimethylsiloxane and 5% polydiphenylsiloxane (TBR-5) was employed to carry out on-line extraction and preconcentration of dibuthyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) in the chromatographic system. The coated capillary was placed between the sample injection loop and the injection needle of an autosampler. Variables affecting the automatic in-tube solid-phase microextraction (SPME) were optimized. A Genesis C(18) (5 cm x 4.6 mm i.d., 4 microm particle size) was employed as analytical column. The achieved limits of detection by use of diode array detection were 1 and 2.5 microg L(-1), respectively. The propo…
Chiral separation of bupivacaine enantiomers by capillary electrophoresis partial-filling technique with human serum albumin as chiral selector
2004
Abstract Capillary electrophoresis (CE) is a powerful technique for enantiomer separations due to its intrinsic high separation efficiencies, speed of analysis, low reagent consumption and small sample requirements. However, some chiral selectors present strong background UV absorption providing high detection limits. The present paper deals with the application of the partial-filling technique to the separation of bupivacaine enantiomers by capillary electrophoresis using human serum albumin (HSA) as chiral selector. In this procedure the cationic surfactant cetyltrimethylammonium bromide (CTAB) was used as a dinamic capillary coating in order to reduce the electro-osmotic flow and detect …
On-line in-tube solid phase microextraction-capillary liquid chromatography method for monitoring degradation products of di-(2-ethylhexyl) phthalate…
2014
Abstract The main di-(2-ethylhexyl) phthalate (DEHP) degradation products, (2-ethylhexyl) phthalate (MEHP), diethyl phthalate (DEP) and dibutyl phthalate (DBP), have been tested. The proposed cost-effective method combines on-line, in-tube solid-phase micro extraction (IT-SPME) in in-valve configuration and capillary liquid chromatography with UV diode array detection (Cap-LC-DAD). Acidification of the samples at pH 3 improved markedly the estimation of MEHP. Aliquots of 4 mL of acidified water samples were directly processed. After sample loading, the analytes were desorbed with the mobile-phase and transferred to the monolithic capillary column. Satisfactory linearity and precision, absen…
In-tube solid-phase microextraction and liquid chromatography using a monolithic column for the selective determination of residual ethylenediamine i…
2009
The selective determination of the diamine ethylenediamine (EDA) in the presence of a higher amount of residual dimethylamine in cationic polymers has been developed. The strategy uses both a solution derivatization with a selective agent of primary amines such as o-phthaldialdehyde-N-acetyl-L-cysteine (OPA-NAC) and an in-tube solid-phase microextraction (IT-SPME) coupled to liquid chromatography (LC). A 70 cm long, 0.32 mm internal diameter, and 3 microm thick commercially available capillary column coated with 95% polydimethylsiloxane and 5% polydiphenylsiloxane was employed to replace the injection loop of a Rheodyne injection valve. A volume of 1 mL of derivatized sample was passed thro…
Cylindrical optical microcavities: Basic properties and sensor applications
2011
Abstract A detailed theoretical analysis of the basic properties of whispering-gallery modes (WGM) of thin capillaries is presented. The sensitivity of the resonances, as well as the Q factor is analyzed as a function of the structural parameters of the capillary and the refractive index inside the capillary. A practical application where thin capillaries are used for the measurement of glucose concentration in water is presented as a chemical sensor demonstrator. A best sensitivity of 1.24 nm/% of glucose concentration in water is reported, which corresponds to more than 850 nm/RIU. Additionally, different experimental approaches are discussed to improve the sensitivity and the detection l…
Selective and sentivive method based on capillary liquid chromatography with in-tube solid phase microextraction for determination of monochloramine …
2015
Abstract Due to the difficulties of working with chloramines, a critical examination of monochloramine standard preparation has been performed in order to select the best synthesis conditions. The analyte has been determined by in-tube solid phase extraction coupled to capillary liquid chromatography with UV detection (IT-SPME Capillary LC DAD). Potential factors affecting the response of monochloramine such as the pH of mobile phase and the volume of sample processed by IT-SPME Capillary LC DAD have been investigated and optimized. According to the results of the study, 0.1 mL or 4.0 mL of sample at neutral pH were loaded in the chromatographic system. A sensitive and selective method has …
Use of gold nanoparticle-coated sorbent materials for the selective preconcentration of sulfonylurea herbicides in water samples and determination by…
2012
Abstract Two new gold nanoparticle (NP) coated materials (silica supported on gold NP with and without ionic liquid) were synthesized for solid phase extraction of sulfonylurea herbicides (SUHs), such as bensulfuron-methyl (BSM), metsulfuron-methyl (MSM), pyrazosulfuron-methyl (PSM), thifensulfuron-methyl (TFM) and triasulfuron (TS), from water samples, followed by capillary liquid chromatography coupled to diode array detection (CLC–DAD). Several factors influencing the preconcentration efficiency of SUHs and its subsequent determination, such as pH of the sample, eluent and reusability of sorbents, have been investigated. Under the optimum conditions, the developed method allowed the dete…
High-throughput capillary electrophoresis frontal analysis method for the study of drug interactions with human serum albumin at near-physiological c…
2004
The application of the short-end capillary injection to capillary electrophoresis frontal analysis (CE-FA) to study the interaction between basic, neutral and acid drugs towards human serum albumin (HSA) at near-physiological conditions is presented. The compounds selected display a wide range of binding affinities and the results obtained were in good agreement with those reported in the literature. An equation for the estimation of the number of primary binding sites and their corresponding affinity constants is developed isolating the experimentally measured variables in just one axis. The proposed CE-FA method to screen drug interactions with HSA under physiological conditions is simple…