Prediction of Reversed-Phase Liquid Chromatography Retention Parameters for Phenylisothiocyanate Derivatives of Amino Acids

2014 ◽  
Vol 52 (1-2) ◽  
pp. 61-70
Author(s):  
S. Vorslova ◽  
J. Golushko ◽  
S. Galushko ◽  
A. Viksna
Keyword(s):  
Amino Acids ◽  
High Performance ◽  
Method Development ◽  
Initial Conditions ◽  
Reversed Phase ◽  
Fine Tuning ◽  
Model Parameters ◽  
Step Method ◽  
Retention Model ◽  
Derivatives Of

Abstract We report our experience with highly polar and charged analyte retention parameter prediction for a reversed-phase high-performance liquid chromatographic method. The solvatic retention model has been used to predict retention of phenylisothiocyanate derivatives of 25 natural amino acids under gradient elution conditions. Retention factors have been calculated from molecular parameters of analyte structures and from the column and eluent characteristics. A step-by-step method which includes the first guess prediction of initial conditions from structural formula and fine tuning of the retention model parameters using data from successive runs can substantially save method development time

scholarly journals Pressurized planar electrochromatography of DNS amino acids derivatives in silica gel and silanized silica gel systems with formic acid addition to the water mobile phase

2021 ◽  
Author(s):  
Adam Chomicki ◽  
Tadeusz H. Dzido
Keyword(s):  
Amino Acids ◽  
Silica Gel ◽  
High Performance ◽  
Reversed Phase ◽  
Mobile Phases ◽  
Phase Systems ◽  
Silanized Silica ◽  
Layer Chromatography ◽  
Derivatives Of ◽  
Electrophoretic Effect

AbstractPressurized planar electrochromatography (PPEC) of dansyl (DNS) derivatives of amino acids in normal- and reversed-phase systems is presented. The results have been obtained for mobile phases with different acetonitrile (ACN) concentrations (0–85%). The data obtained show differences in separation selectivity between high-performance thin-layer chromatography (HPTLC) and PPEC systems. These differences originate from the electrophoretic effect which is involved in the PPEC system, contrary to the HPTLC one.

Directed biosynthesis of novel derivatives of echinomycin. II. Purification and structure elucidation

1984 ◽  
Vol 30 (6) ◽  
pp. 730-738 ◽  
Author(s):  
D. Gauvreau ◽  
M. J. Waring
Keyword(s):  
High Performance ◽  
Reversed Phase ◽  
Aromatic Acids ◽  
Antibacterial Assay ◽  
New Antibiotics ◽  
Field Desorption Mass Spectrometry ◽  
Directed Biosynthesis ◽  
Phase Systems ◽  
Derivatives Of ◽  
Acid Precursor

New antibiotics produced by Streptomyces echinatus A8331 cultured in the presence of heterocyclic aromatic acids can be separated and purified by high-performance liquid chromatography using reversed phase columns. Natural quinoxaline antibiotics and certain quinoline derivatives can also be efficiently separated in normal phase systems. Details of purification procedures are described together with experiments to characterise the new antibiotics by field desorption mass spectrometry and proton magnetic resonance. Mono- and bis-substituted derivatives of echinomycin containing the following replacement chromophores have been isolated: 7-chloroquinoxaline-2-carbonyl, thieno[3,2-b]pyridine-5-carbonyl, and 6-methylquinoline-2-carbonyl. With a 6-methylquinoline-2-carboxylic acid precursor the analogues containing one or two replacement chromophores are each separable into two distinct components. One of the bis-substituted 6-methylquinoline products appears inactive in an antibacterial assay and behaves as a triostin analogue, presumably an immediate precursor of the corresponding echinomycin derivative.

BIO ANALYTICAL METHOD DEVELOPMENT AND VALIDATION FOR SIMULANEOUS ESTIMATION OF NITAZOXANIDE AND OFLOXACIN IN HUMAN PLASMA BY RP-HPLC

INDIAN DRUGS ◽  
2021 ◽  
Vol 57 (10) ◽  
pp. 47-57
Keyword(s):  
Human Plasma ◽  
High Performance ◽  
Method Development ◽  
Reversed Phase ◽  
Chromatography Method ◽  
Rp Hplc ◽  
Method Development And Validation ◽  
Liquid Chromatography Method ◽  
Development And Validation ◽  
Lower Limits

An isocratic Reversed-Phase High Performance Liquid Chromatography method has been developed for rapid and simultaneous separation and estimation of two antibiotics, namely, nitazoxanide and ofloxacin, in human plasma. Separation was carried out on Altima C8 (150 x 4.6 mm, 5µ) column using a mobile phase of 0.1% ortho phosphoric acid: acetonitrile (50:50, V/V) at 260 nm. The retention time of nitazoxanide and ofloxacin was noted to be 4.850 and 7.949 min, respectively. The average % recovery for nitazoxanide and ofloxacin were 98.012 % and 94.176 %, respectively and reproducibility was found to be satisfactory. The linearity was investigated in the concentration range of 0.02-2 µg/ml (r2=0.9996) for nitazoxanide and 0.008-0.8 µg/ml (r2=0.9998) for ofloxacin. The lower limits of quantification were 0.0196 µg/ml and 0.0079 µg/ml for nitazoxanide and ofloxacin, respectively, which reach the level of both drugs possibly found in human plasma. The proposed method can be applied for etermination of nitazoxanide and ofloxacin from dosage forms during pharmacokinetic study.

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