Separation Of Tryptophan Research Articles

Preparation and performance characterization of gold nanoparticles modified chiral capillary electrochromatography stationary phase

Gold nanoparticles (GNPs, 15 nm) were prepared and introduced to amino groups derived silica monolithic column. Bovine serum albumin (BSA) was immobilized via covalent modification method onto the carboxylic functionalized GNPs to afford chiral stationary phase (CSP) for enantioseparation. GNPs were well dispersed and successfully incorporated onto the columns with the contents as high as 17.18% by characterization method such as transmission electron microscopy (TEM), ultraviolet (UV)-visible absorption spectra and scanning electron microscopy (SEM). The preparation conditions of the BSA modified CSP were optimized and 10% (v/v) 3-aminopropyltriethoxysilane (APTES) and 15 g/L BSA were selected as appropriate reaction conditions. The enantioseparation performance of the BSA modified CSP has been investigated by capillary electrochromatography (CEC). Enantiomers of tryptophan, ephedrine and atenolol were resolved, and the baseline separation of tryptophan was achieved. Meanwhile, the influences of pH value, buffer concentrations and applied voltages used on the chiral separation were studied, and the optimal separation conditions were 10 mmol/L phosphate buffer at pH 7.4 and 15 kV applied voltages. In comparison with the BSA modified CSP prepared by physical adsorption, the CSP prepared by covalent modification method had better separation results, and the analytes could be separated directly without pre-column derivatization. In addition, the prepared BSA modified CSP exhibited good run to run repeatability with relative standard deviations (RSDs) of the migration times and selectivity factors not more than 2.3% and 0.96%, respectively. This work offers a good thinking for modification with other proteins or other types of chiral selectors.

Surfactants modified silica phase for sorption studies of essential amino acids by thin layer chromatography

A new thin layer chromatographic system comprising silica layer impregnated with an anionic surfactant, 0.001 M sodium dodecyl sulphate (SDS) as stationary phase and borate–phosphate buffer (pH 2.3) as mobile phase was identified as most favourable system for the mutual separation of l-histidine and dl-tryptophan. The presence of amines, inorganic anions and metal cations as impurities in the sample were examined for the separation of l-histidine from dl-tryptophan. The lowest detectable amount for these two amino acids, stability of the mixture of l-histidine and dl-tryptophan and reproducibility of the R F values were determined. Chromatographic parameters like separation factor and resolution for the separation of l-histidine and dl-tryptophan on silica TLC plates as well as on silica gel 60 F 254 HPTLC plates were evaluated and compared. Tryptophan as an impurity at 0.25 μg level in amino acids ( l-histidine, dl-methionine, l-lysine, dl-threonine and l-leucine) sample was detected as violet-blue fluorescing spot under UV radiation. The proposed method is rapid and applicable to the identification and separation of tryptophan in drug samples.

Enantiomeric Separation of Tryptophan by Ultrafiltration Using the BSA Solution System

The optical resolution of racemic tryptophan was performed by ultrafiltration using the BSA solution system. The pH of the feed solution had a strong influence on the complexation constants between BSA and tryptophan, especially for L-tryptophan. The complexation constant for L-tryptophan reached a maximum value at pH 9 (K L = 110,000), varying by 2 orders of magnitude in the range from pH 6 (K L = 1000) to pH 11 (K L = 21,000). Smaller variations of the complexation constant of D-tryptophan were observed. Based on these data, the recovery and the purity of the permeate were optimized by a proper control of the physicochemical parameters of the feed solution (essentially pH and initial concentrations). In one stage, 91% purity with a 89% recovery of D-tryptophan has been easily obtained with a high permeation rate (6.3 × 10−4 mol·m−2s−1 at 1.5 bar).

Separation of tryptophan from DSIP, a Trp-nonapeptide, by adsorption to aluminum oxide

Delta sleep-inducing peptide (DSIP) has been found to induce sleep as well as extra-sleep effects. Although the presence of endogenous DSIP-like material has been demonstrated, the metabolic fate of injected DSIP has not been clarified so far. A major obstacle in monitoring degradation of DSIP has been the lack of an easy method to separate DSIP from tryptophan (Trp). Cleavage of the N-terminal Trp apparently represents the first and most important step in the metabolism of the peptide. Adsorption to aluminum oxide has been found to separate the two compounds and optimal conditions for the separation are described. Quantitative determination of the degradation of DSIP in plasma or serum is now rapidly achieved. The method should help to advance metabolic studies of DSIP. Other applications such as extraction of DSIP from solutions are also possible.

Fluorometric Determination of Tryptophan and Its Brain Indoleamine Metabolites by Ion-Pair HPLC

Abstract The reverse phase HPLC separation of tryptophan, serotonin, 5-hydroxyindoleacetic acid, tryptamine and indoleacetic acid using two solvent systems (one of them containing an ion-pairing reagent) is reported. The two low concentration eluents employed are either formic acid/water or 0.005 mol/L solution of 1-pentane sulfonn ic acid. In both cases chromatographic separation was achieved through a linear gradient elution using methanol/water (7/3) as the high concentration eluent. We also describe the variation of retention volumes of these compounds as a function of the pH of the mobile phase. pH values ranged from 1.5 to 4.0 and were obtained by adding either formic acid or NaOH respectively to the low concentration eluent. Tryptophan and its metabolites were detected fluorometrically. All compounds show a linear response in the pg to μg range. The chromatographic separation achieved allows a concurrent measurement of tryptophan and its main indoleamine metabolites which coupled to the high sensit...

Chromatographic separation of tryptophan metabolites

Separation of tryptophan and 15 metabolites by ion-exchange chromatography using Sephadex QAE-A25 and carboxymethyleellulose in a continuous system is reported. The system employs a complex NaCl gradient to elute the QAE-A25 column, and a simple linear NaCl gradient to elute the CMC column. Detection was achieved by a dual-beam UV analyzer or a flowthrough filter fluorometer. The UV unit allows sample detection on the order of 10 μg and the fluorometer allows the detection of 1 μg or less depending on the compound. Ultraviolet spectra at 3 pH valves and extinction coefficients are given for 16 compounds. UV absorption and fluorometric determinations of recovery from chromatographic separation of a mixture of tryptophan metabolites showed recovery to be 100 ± 5%.