Search results for "liquid chromatography"
showing 10 items of 942 documents
Applications of Electromigration Techniques: Applications of Electromigration Techniques in Food Analysis
2013
Electromigration techniques, including capillary electrophoresis (CE), are widely used for separation and identification of compounds present in food products. These techniques may also be considered as alternate and complementary with respect to commonly used analytical techniques, such as high-performance liquid chromatography (HPLC), or gas chromatography (GC). Applications of CE concern the determination of high-molecular compounds, like polyphenols, including flavonoids, pigments, vitamins, food additives (preservatives, antioxidants, sweeteners, artificial pigments) are presented. Also, the method developed for the determination of proteins and peptides composed of amino acids, which …
No evidence of ATP1A2 involvement in 12 multiplex Italian families with benign familial infantile seizures
2005
A missense mutation in the gene encoding the alpha(2) Subunit of the Na+,K+ ATPase pump (ATP1A2) was found in a family with both familial hemiplegic migraine (FHM) and Benign Familial Infantile Seizures (BFIC). As it is still unclear whether ATP1A2 is responsible for pure BFIC syndromes, we checked mutations of the ATP1A2 gene in probands of 12 Italian multiplex families with pure BFIC, who were negative for mutations in the SCN2A gene. We screened the ATP1A2 gene by denaturing high performance liquid chromatography (D-HPLC) and direct sequencing of DNA fragments showing an aberrant elution pattern. We found one exonic variant and five intronic variants, none leading to significant amino ac…
HPLC demonstration that an all Trp--Phe replacement in gramicidin A results in a conformational rearrangement from beta-helical monomer to double-str…
1995
We have taken advantage of our previously reported high performance liquid chromatographic (HPLC) strategy to investigate the conformational behavior of the optically reversed gramicidin M (gM-), an analog of gramicidin A with all tryptophans replaced by phenylalanines, in different model membranes. It is quantitatively demonstrated for the first time that once inserted in the lipid environment, gM- (unlike the native peptide) undergoes a conformational transition from beta-helical monomers to thermodynamically stable double-stranded dimers. This transition is faster the higher the incubation temperature and can be neatly observed in both small unilamellar phospholipid vesicles and lysophos…
Versatile, sensitive liquid chromatography mass spectrometry – Implementation of 10 μm OT columns suitable for small molecules, peptides and proteins
2016
AbstractWe have designed a versatile and sensitive liquid chromatographic (LC) system, featuring a monolithic trap column and a very narrow (10 μm ID) fused silica open tubular liquid chromatography (OTLC) separation column functionalized with C18-groups, for separating a wide range of molecules (from small metabolites to intact proteins). Compared to today’s capillary/nanoLC approaches, our system provides significantly enhanced sensitivity (up to several orders) with matching or improved separation efficiency, and highly repeatable chromatographic performance. The chemical properties of the trap column and the analytical column were fine-tuned to obtain practical sample loading capacities…
Nanoparticle Size Is a Critical Physicochemical Determinant of the Human Blood Plasma Corona: A Comprehensive Quantitative Proteomic Analysis
2011
In biological fluids, proteins associate with nanoparticles, leading to a protein "corona" defining the biological identity of the particle. However, a comprehensive knowledge of particle-guided protein fingerprints and their dependence on nanomaterial properties is incomplete. We studied the long-lived ("hard") blood plasma derived corona on monodispersed amorphous silica nanoparticles differing in size (20, 30, and 100 nm). Employing label-free liquid chromatography mass spectrometry, one- and two-dimensional gel electrophoresis, and immunoblotting the composition of the protein corona was analyzed not only qualitatively but also quantitatively. Detected proteins were bioinformatically cl…
Label-free profiling of skeletal muscle using high-definition mass spectrometry
2014
We report automated and time efficient (2 h per sample) profiling of muscle using ultra-performance liquid chromatography (LC) coupled directly with high-definition mass spectrometry (HDMSE). Soluble proteins extracted from rat gastrocnemius (n=10) were digested with trypsin and analysed in duplicate using a 90 min RPLC gradient. Protein identification and label-free quantitation were performed from HDMSE spectra analysed using TransOmics Informatics for Proteomics software. In total 1,514 proteins were identified. Of these, 811 had at least 3 unique peptides and were subsequently used to assess the dynamic range and precision of LC-HDMSE label-free profiling. Proteins analysed by LC-HDMSE …
"Design and application of a data-independent precursor and product ion repository."
2012
The functional design and application of a data-independent LC-MS precursor and product ion repository for protein identification, quantification, and validation is conceptually described. The ion repository was constructed from the sequence search results of a broad range of discovery experiments investigating various tissue types of two closely related mammalian species. The relative high degree of similarity in protein complement, ion detection, and peptide and protein identification allows for the analysis of normalized precursor and product ion intensity values, as well as standardized retention times, creating a multidimensional/orthogonal queryable, qualitative, and quantitative spac…
Column switching and high-performance liquid chromatography in the analysis of amitriptyline, nortriptyline and hydroxylated metabolites in human pla…
1992
A column-switching system for the direct injection of plasma or serum samples, followed by isocratic high-performance liquid chromatography and ultraviolet detection, is described for the simultaneous quantitation of the tricyclic antidepressant amitriptyline, its demethylated metabolite nortriptyline and the E- and Z-isomers of 10-hydroxyamitriptyline and 10-hydroxynortriptyline. The method included adsorption of amitriptyline and metabolites on a reversed-phase C8 clean-up column (10 microns; 20 mm x 4.6 mm I.D.), washing of unwanted material to waste and, after on-line column-switching, separation on a cyanopropyl analytical column (5 microns; 250 mm x 4.6 mm I.D.). The compounds of inte…
Physicochemical compatibility and stability of nebulizable drug admixtures containing Dornase alfa and tobramycin.
2012
The objective of this in-vitro study was to determine whether admixtures of the inhalation solutions Pulmozyme(®) (Dornase alfa) and either Bramitob(®) or Tobi(®) (both containing Tobramycin) are physicochemically compatible and to analyze the aerodynamic parameters of these admixtures. After mixing, test solutions were stored at room temperature and under ambient light conditions over a period of 24 h. Tobramycin concentrations were determined by using a fluorescence immunoassay. Stability of dornase alfa was determined by size-exclusion high performance liquid chromatography, ultraviolet spectroscopy, sodium dodecyl sulfate polyacrylamide gel electrophoresis and tentacle strong cation-exc…
Quantitative and qualitative control of antineoplastic preparations: Gravimetry versus HPLC.
2019
This article compares gravimetry vs. high-performance liquid chromatography (HPLC) as quality control (QC) methods for paclitaxel, docetaxel and oxaliplatin preparations. We aimed at assessing the preparation method reliability in our hospital, evaluating compounding accuracy and estimating the influence of personnel training and standardized homogenization on compounding accuracy. Agreement, correlation, concordance, accuracy and precision between methods were evaluated for each drug. Conforming preparation percentages (CPs) at different tolerance limits (TLs) and compounding accuracy were calculated for each method and drug. Compounding accuracy was compared before and after personnel tra…