Search results for "liquid"

Separation of selected peptides by capillary electroendoosmotic chromatography using 3 μm reversed-phase bonded silica and mixed-mode phases

1999

The retention behaviour and selectivity of selected basic, neutral and acidic peptides have been studied by capillary electroendoosmotic chromatography (CEC) with Hypersil C8, C18, Hypersil mixed-mode, and Spherisorb C18/SCX columns, 250 (335) mm x 100 microns, packed with 3 microns particles, and eluted with mobile phases composed of acetonitrile-triethylamine-phosphoric acid (TEAP) at pH 3.0 using a Hewlett-Packard Model HP3DCE capillary electrophoresis system. The selected peptides were desmopressin (D), two analogues (A and B) of desmopressin, oxytocin (O) and carbetocin (C). The peptides eluted either before or after the electroendoosmotic flow (EOF) marker, depending on the concentrat…

Are deep eutectic solvents useful in chromatography? A short review.

2021

A literature update has been done concerning Deep Eutectic Solvents (DES) use in chromatography applications. The literature survey was based on the period from 2010 till 2020 and manuscripts reported in the data bases Web of Science and Scopus. The use of DES as mobile phase and mobile phase additives, stationary phases and solid phase modifiers and the use of DES as reaction solvents for chromatography use, were evaluated. Emphasis was placed on the differentiation of DES and Ionic Liquids (ILs) and the advanced green characteristics of the new solvents as compared with traditional organic solvents and ILs with a look into the drawbacks and future perspectives in the field of separation m…

Performance of Markers and the Homologous Series Method for Dead Time Estimation in Reversed-Phase Liquid Chromatography

2009

Abstract Two methods for dead time estimation (the use of markers and the homologous series mathematical method) are revised. Out of twelve assayed common markers, only KBr, KI, tartrazine, thiourea, uracil, and urea yielded retention times independent of the mobile phase composition in the range 10–90% acetonitrile, using a Zorbax Eclipse XDB−C18 column. On the other hand, the quality of the estimations provided by the homologous series method was limited by the mathematical approach and the data quality. With this method, the estimated dead time is an extrapolated value, which is severely affected by the data of the most retained compounds that act as leverage points, biasing the result. …

Determination of Lobenzarit Disodium in Human Plasma by High-Performance Liquid Chromatography

1998

Abstract A reversed-phase high performance liquid chromatographic procedure was developed for determination of lobenzarit disodium in human plasma over the range 0.5−17.5 μg/mL with diphenylamine as internal standard. Plasma samples were extracted with acetonitrile and an aliquot was injected onto a Lichrospher 100 RP-18 column with ultraviolet absorbance detection at 308 nm. Composition of the mobile phase was acetonitrile-water-glacial acetic acid (50:50:0.2 v/v/v).

A theoretical plate model accounting for slow kinetics in chromatographic elution.

2011

The chromatographic elution has been studied from different perspectives. However, in spite of the simplicity and evident deficiencies of the plate model proposed by Martin and Synge, it has served as a basis for the characterization of columns up-to-date. This approach envisions the chromatographic column as an arbitrary number of theoretical plates, each of them consisting of identical repeating portions of mobile phase and stationary phase. Solutes partition between both phases, reaching the equilibrium. Mobile phase transference between the theoretical plates is assumed to be infinitesimally stepwise (or continuous), giving rise to the mixing of the solutions in adjacent plates. This yi…

Insect immunity. Constitutive expression of a cysteine-rich antifungal and a linear antibacterial peptide in a termite insect

2001

0021-9258 (Print) Journal Article Research Support, Non-U.S. Gov't; Two novel antimicrobial peptides, which we propose to name termicin and spinigerin, have been isolated from the fungus-growing termite Pseudacanthotermes spiniger (heterometabole insect, Isoptera). Termicin is a 36-amino acid residue antifungal peptide, with six cysteines arranged in a disulfide array similar to that of insect defensins. In contrast to most insect defensins, termicin is C-terminally amidated. Spinigerin consists of 25 amino acids and is devoid of cysteines. It is active against bacteria and fungi. Termicin and spinigerin show no obvious sequence similarities with other peptides. Termicin is constitutively p…

Purification and molecular weight determination of the membrane protein cytochrome o-complex from Rhodospirillum rubrum by high-performance liquid ch…

1988

Off-line dansylation of amines using C18 solid-phase packings: study of the fluorescence and chemiluminescence detection by post-column derivatizatio…

1999

Abstract Dansylation of amines (primaries and secondaries) using C18 solid-phase supports is described. The time of analysis and the handing sample have been markedly improved with respect to those required for solution dansylation. The dansylated amine derivates were injected onto the liquid chromatography system and fluorescence detected. The sensitivity and selectivity is better than the other dansylation procedures described in the literature and also better than other derivatization reagents such 1,2-napthoquinone 4-sulfonate (NQS) or 3,5-dinitrobenzoyl chloride (3,5-DNB). Dansyl compounds can also form chemiluminescent derivatives, therefore a post-column derivatization procedure with…

Metabolites of the aquatic pollutant diclofenac in fish bile.

2010

The uptake and metabolism of anti-inflammatory drug diclofenac (DCF) was studied by exposing rainbow trout (Oncorhynchus mykiss) to DCF intraperitoneally, and via water at concentration of 1.7 μg L(-1). The bile was collected and the formed metabolites were identified. The identification was based on the exact mass determinations by a time-of-flight mass analyzer and on the studies of fragments and fragmentation patterns of precursor ions by an ion trap mass analyzer. The main metabolites found were acyl glucuronides of hydroxylated DCFs. In addition, one ether glucuronide of hydroxylated DCF was found. Also, unmetabolized DCF was detected in the bile. The total bioconcentration factors (BC…

A rapid and cost-efficient DMSO-based method for isolating DNA from cultured lichen photobionts

2010

We have developed a simple and fast procedure for the purification of PCR-quality DNA from cultured lichen photobionts. This new one-step method uses the solvent dimethyl sulfoxide (DMSO) combined with heat treatment to chemically breakdown algal and plant tissues. The DMSO-DNA extracts may be directly precipitated and purified by standard techniques in a total time of approximately 30 min. Compared to other DNA extraction protocols, the DMSO-based method suppresses the need for liquid nitrogen, any extraction buffer, grinding, phenol, and long incubation or centrifugation steps, thereby considerably reducing the possibility of contamination. In addition, minimal amounts of starting materia…