Search results for "Elution"
showing 10 items of 337 documents
Quality control of pharmaceuticals containing non-steroidal anti-inflammatory drugs by micellar liquid chromatography
2002
A liquid chromatographic procedure is described for the determination of acemetacin, diclofenac, indomethacin, ketoprofen, nabumetone, naproxen, piketoprofen, and tolmentin in pharmaceutical preparations. The compounds were separated on a Kromasil C18 analytical column, with a guard column of similar characteristics; the mobile phase was 0.06 M cetyltrimethylammonium bromide, at pH 7, containing 10% 1-butanol. At a flow rate of 1 mL min−1 the elution time of the most retained compound was 23 min. Limits of detection were between 0.01 μ g mL−1 for diclofenac and 0.2 μ g mL−1 for naproxen. The proposed method enables the determination of non-steroidal anti-inflammatory drugs in pharmaceutical…
Comparison between sodium dodecylsulphate and cetyltrimethylammonium bromide as mobile phases in the micellar liquid chromatography determination of …
2004
The retention behaviour of non-steroidal anti-inflammatory drugs (NSAIDs) using micellar mobile phases of sodium dodecylsulphate (SDS) is studied and compared with that observed with micellar mobile phases of cetyltrimethylammonium bromide (CTAB). A liquid chromatographic procedure for the determination of acemetacin, diclofenac, indomethacin, ketoprofen, naproxen and tolmetin in pharmaceutical preparations is described. The proposed system uses a Kromasil C18 analytical column and a solution of 0.15 M SDS at pH 3 with 10% 1-propanol as mobile phase. Under these conditions, the studied NSAIDs elute between 6 and 10 min at a 1 mL min(-1) flow rate. Limits of detection (LOD) are lower than 0.…
Polymeric monolithic microcartridges with gold nanoparticles for the analysis of protein biomarkers by on-line solid-phase extraction capillary elect…
2020
In this study, polymeric monoliths with gold nanoparticles (AuNP@monolith) were investigated as microcartridges for the analysis of protein biomarkers by on-line solid-phase extraction capillary electrophoresis-mass spectrometry (SPE-CE-MS). “Plug-and-play” microcartridges (7 mm) were prepared from a glycidyl methacrylate (GMA)-based monolithic capillary column (5 cm x 250 µm i.d.), which was modified with ammonia and subsequently functionalized with gold nanoparticles (AuNPs). The performance of these novel microcartridges was evaluated with human transthyretin (TTR), which is a protein related to different types of familial amyloidotic polyneuropathies (FAP). Protein retention depended on…
Measurement of Duloxetine in Blood Using High-performance Liquid Chromatography with Spectrophotometric Detection and Column Switching
2007
A method using high-performance liquid chromatography (HPLC) with column switching and ultraviolet (UV) spectroscopy was developed for the determination of duloxetine in human plasma. After centrifugation and addition of venlafaxine as internal standard, plasma samples were injected into the HPLC system and precleaned on a column (10 x 4.0 mm) filled with cyanopropyl (CN)-modified silica of 20 microm particle size, with use of 8% (vol/vol) acetonitrile in deionized water as eluent. Duloxetine was eluted and separated on a LiChrospher 100 CN (5-microm particle size; column size, 250 x 4.6 mm I.D.) using acetonitrile-water-potassium dihydrogenphosphate trihydrate buffer (pH, 6.4; 50:50 vol/vo…
Alternating current voltammetric determination of DNA damage
1990
Abstract The conditions for alternating current (a.c.) voltammetric DNA determinations have been investigated with respect to its use with alkaline filter elution techniques at low DNA concentrations. In inorganic electrolyte solutions three current peaks can be distinguished: peak I around −1.1 V caused by the reorientation or desorption of DNA segments; peak II around −1.2 V caused by the native DNA (nDNA) form; peak III caused by denatured DNA (dDNA) at −1.4 V. Sonication of nDNA increases the peak current, however not with dDNA. Both dDNA and nDNA give linear peak current increments with DNA increments, their regression lines cutting the concentration axis at the origin. In filter eluti…
Gradient high-performance liquid chromatography of statistical and block copolymers of styrene and t-butyl methacrylate
1989
Copolymers of styrene (S) and tert-butyl methacrylate (TBMA) containing 24–92 mass % of the latter monomer were investigated using a silica column with isooctane/tetrahydrofuran (THF) gradients and on a phenyl bonded-phase column by methanol (MeOH)/THF gradients using UV detection. In both cases, retention decreased with increasing TBMA content of the sample. This is in contrast to the behavior of copolymers of S and methyl methacrylate (MMA) whose retention in gradient elution on silica columns increases with MMA content due to the polarity of this unit. The inversion of elution order is a result of the bulky TBMA residues shielding the polar groups of the ester units. For copolymers of va…
Kinetics and isotherm of fibronectin adsorption to three-dimensional porous chitosan scaffolds explored by125I-radiolabelling
2013
In this study, 125I-radiolabelling was explored to follow the kinetics and isotherm of fibronectin (FN) adsorption to porous polymeric scaffolds, as well as to assess the elution and exchangeability of pre-adsorbed FN following incubation in serum-containing culture medium. Chitosan (CH) porous scaffolds with two different degrees of acetylation (DA 4% and 15%) were incubated in FN solutions with concentrations ranging from 5 to 50 µg/mL. The kinetic and isotherm of FN adsorption to CH were successfully followed using 125I-FN as a tracer molecule. While on DA 4% the levels of adsorbed FN increased linearly with FN solution concentration, on DA 15% a saturation plateau was attained, and FN a…
Gamma-ray spectrometric measurement of radionuclide purity of radiopharmaceuticals contained in bottle samples
2012
The radionuclide purity of a radiopharmaceutical product is usually measured by gamma-ray spectrometry with various measurement geometries. The importance of this test is that the radionuclide impurities, if present, result in an increase in the radiation dose to the patient without contributing to diagnostic information and in some cases may also interfere with the marking molecules and affect the proper conduct of diagnostic examination. In this work, gamma-ray spectrometry is used to determine the amounts of impurities by adopting as measurement geometry the same bottle containing eluted or prepared radiopharmaceuticals. In addition to high-purity germanium semiconductor detectors, the u…
Evaluation of a Multidimensional Solid-Phase Extraction Platform for Highly Selective On-Line Cleanup and High-Throughput LC−MS Analysis of Triazines…
2001
A novel highly selective sample cleanup procedure based on the use of molecularly imprinted polymers (MIPs) as solid-phase extraction materials has been evaluated with respect to its applicability and routine use in environmental analysis. The method comprises the combination of a restricted access material (RAM) and a MIP allowing a selective sample preparation to be achieved in the online mode. This combination is called the size-selective sample separation and solvent switch (six-SPE). The RAM column combines size exclusion and adsorption chromatography, reducing the concentration of matrix molecules by a cutoff of 15 kDa. The MIP column selectively retains the triazine analytes whereas …
Sensitive sequential-injection system for the determination of 2-phenylbenzimidazole-5-sulphonic acid in human urine samples using on-line solid-phas…
2003
Abstract 2-Phenylbenzimidazole-5-sulphonic acid (PBS) is an UV-filter contained in many cosmetics as a sunscreen. A direct, selective and sensitive method to determine traces of PBS is presented. The on-line separation of this compound from urine matrix was directly coupled with fluorimetric detection in a sequential-injection system. The separation was performed using a SAX microcolumn in which the analyte was retained and eluted selectively. The determination is carried out without any derivatization reaction, by directly measuring the intrinsic fluorescence of the analyte. The wavelengths of excitation and emission were 301 and 681 nm, respectively. On-line standard addition calibration …