Search results for "Elution"
showing 10 items of 337 documents
Prediction of chromatographic parameters for some anilines by molecular connectivity
1995
The possible relation existing between RF values obtained by thin-layer chromatography for a group of anilines with connectivity indices proposed by Kier and Hall has been studied. Using multivariable regression the corresponding connectivity functions, selected for their respective correlation coefficients, standard deviations, Snedecor's F and Student's t were obtained. Regression analysis of the connectivity functions gives a correct prediction of the experimental elution sequence for this group of substances on silica gel stationary phases and various mobile phases of different polarity. The corresponding random and stability studies of the different prediction models selected were carr…
Quantitative online isolation of 68Ge from 68Ge/68Ga generator eluates for purification and immediate quality control of breakthrough
2013
The breakthrough of ⁶⁸Ge from a ⁶⁸Ge/⁶⁸Ga-generator is one of the most sensitive parameters in the context of the clinical application of ⁶⁸Ga-radiopharmaceuticals. The difficulty in its determination lies in the "spectroscopic invisibility" of ⁶⁸Ge within an excess of ⁶⁸Ga. The introduced method for determining the ⁶⁸Ge content of the ⁶⁸Ge/⁶⁸Ga-generator eluate involves the quantitative separation of ⁶⁸Ga from ⁶⁸Ge, using a cation-exchanger. The eluate contains ⁶⁸Ga free of ⁶⁸Ge, which can be determined immediately, i.e. prior to the application of the ⁶⁸Ga-radiopharmaceutical.
68Ge content quality control of 68Ge/68Ga-generator eluates and 68Ga radiopharmaceuticals – A protocol for determining the 68Ge content using thin-la…
2014
(68)Ge breakthrough from a (68)Ge/(68)Ga-generator appears to be one of the most critical parameters for the routine clinical application of this generator and (68)Ga-radiopharmaceuticals. We report a TLC-based (thin-layer chromatography) protocol which allows the (68)Ge breakthrough of a generator to be determined within 1 h post-initial elution. The protocol can also be adapted to allow the (68)Ge content of a (68)Ga-radiopharmaceutical preparation to be determined prior to in vivo application.
Post-elution processing of 44Ti/44Sc generator-derived 44Sc for clinical application
2009
The (44)Ti/(44)Sc (T(1/2)(44)Ti=60a) generator provides cyclotron-independent access to positron-emitting (44)Sc (T(1/2)=3.97d) for PET imaging. This work aims to post-elution processing of initial (44)Sc generator eluates in order to reduce its volume, HCl concentration and remove the oxalate anions. The on-line adsorption of (44)Sc on cationic resin AG 50W-X8 (200-400 mesh, H(+)-form) is achieved with >98% efficacy. Subsequently, the purified (44)Sc is desorbed by using 3ml of 0.25M ammonium acetate (pH=4.0). The post-processing takes 10min. The overall yield of the post-processing reached 90%, which is referred to the (44)Sc obtained from the (44)Ti/(44)Sc generator. In addition to the c…
Hydrodynamic chromatography of macromolecules on small spherical non-porous silica particles
1990
Abstract Non-porous silica spheres with sizes in the range 1.4–2.7 μm were applied as packings for the hydrodynamic chromatography (HDC) of macromolecules. Highly efficient columns, with a reduced plate height below 2, were packed with these small particles. Up to molecular weights of 10 6 the elution behaviour of polystyrenes agreed very well with existing theoretical models. However, for larger polystyrenes the flow-rate exerted an influence on the relative peak positions. The applicability of HDC to rapid separations of soluble macromolecules and inorganic colloids was demonstrated.
Use of triacylglycerol profiles established by high performance liquid chromatography with ultraviolet–visible detection to predict the botanical ori…
2011
A method for the determination of triacylglycerols (TAGs) in vegetable oils from different botanical origins by HPLC with UV–vis detection has been developed. Using a core-shell particle packed column (C18, 2.6 micron), TAG separation was optimized in terms of mobile phase composition and column temperature. Using isocratic elution with acetonitrile/n-pentanol at 10 °C, excellent efficiency with good resolution between most of the TAG peak pairs, within a total analysis time of 15 min, was achieved. Using mass spectrometry detection, a total of 15 peaks, which were common to oils of six different botanical origins (corn, extra virgin olive, grapeseed, hazelnut, peanut and soybean) were iden…
High-performance liquid chromatographic separation of modified and native melittin following transglutaminase-mediated derivatization with a dansyl f…
1991
Abstract The 26-amino acid linear, amphiphilic peptide melittin was enzymatically modified with the fluorescent probe monodansylcadaverine using guinea pig liver transglutaminase and a fluorescent derivative of stoichiometry 1:1 was obtained. Reversed-phase and size-exclusion high-performance liquid chromatographic modes were tested in order to resolve the labelled peptide and native species. The influence of several operational variables was analysed and the elution conditions were optimized so that a satisfactory resolution could be achieved in both instances in a rapid, easy manner. Both chromatographic modes offer the possibility of accurate monitoring of the time course of the enzyme-m…
On-line in-tube solid phase microextraction coupled to capillary liquid chromatography-diode array detection for the analysis of caffeine and its met…
2019
Abstract In-tube solid phase microextraction (IT-SPME) coupled on-line to capillary liquid chromatography with diode array detection provides a simple and fast analytical methodology for the simultaneous quantitation of caffeine and its three primary metabolites (theobromine, paraxanthine and theophylline) in micro samples of serum, saliva and urine matrices. The sample amount required for one analysis was only 2.5 μL of saliva, 6.25 μL of serum or 40 μL of urine, a requirement for its implementation in a hospital laboratory for preterm newborns, where sample availability is a major problem. In standard conditions, 25 μL of diluted saliva or serum (or 100 μL of urine) were processed by IT-S…
Dissection of C1q Capability of Interacting with IgG
1997
Abstract C1q-bearing immune complexes have been observed in diseases such as rheumatoid arthritis and human immunodeficiency virus infection-associated neuropathy. For the purpose of understanding better the phenomenon of C1q-bearing immune complexes, we investigated the constancy of the C1q-IgG interaction. An enzyme-linked immunosorbent assay was developed in which wells were coated with IgG to mimic antigen-complexed IgG. Serial dilutions of C1q were applied for distinct time intervals, and bound C1q was detected either directly or after exposure to one of several elution buffers. Our results show that a part of C1q attached to IgG forms a tight association that is not reversible under t…
Determination of benzomercaptans in environmental complex samples by combining zeolitic imidazolate framework-8-based solid-phase extraction and high…
2020
[EN] In this work, the synthesis of zeolitic imidazolate framework-8 (ZIF-8) crystals and their subsequent application as effective sorbents for extraction and preconcentration of several benzomercaptans from environmental complex samples is described. These materials were prepared by solvothermal approach varying the concentration of n-butylamine modulator to modify the surface of the metal-organic framework. The resulting materials were characterized by scanning and transmission electron microscopy, powder X-ray diffraction and Fourier transform infrared spectroscopy. The ZIF-8 material that gave the best features was selected as extractive phase and the influence of various parameters (s…