Analytical and Preparative Reverse Phase HPLC of Porphyrin C and N,N′-Diacetyl Porphyrin C

Abstract

Efficient high-performance liquid chromatographic (HPLC) conditions have been developed for the routine analysis of the therapeutically useful form of porphyrin c as the free acid. Porphyrin c and its diacetyl derivative have been resolved into their diastereoisomers. Preparative HPLC conditions for the purification of porphyrin c and its diacetyl derivative have also been developed.     

Detectors for Liquid Chromatographic Analysis for Polynuclear Aromatic Hydrocarbons

Abstract

A number of liquid chromatographic detectors of various types have been evaluated for both selectivity and sensitivity for the detection of polynuclear aromatic hydrocarbons (PAH). Detection limits for fixed and variable wavelength UV photometers, filter fluorimeters, and spectrofluorimeters have been determined. The utility of each of these types of detectors for use in the reversed-phase HPLC analysis of environmental extracts containing trace levels of PAH's is discussed.     

A High Performance Liquid Chromatographic Assessment of the Isolation of Bovine Proinsulin and a Synthetic Proinsulin Fragment

Abstract

High performance liquid chromatographic techniques have been used for the analysis and purification of the bovine proinsulin C-peptide fragment 34–45 (H-Val-Glu-Gly-Pro-Gln-Val-Gly-Ala-Leu-Glu-Leu-Ala-OH) (I) prepared solid phase synthetic methods. Conventional open column chromatographic methods failed to resolve the desired dodecapeptide (I)' from the des-Pro⁹-undecapeptide (II), which constituted the major solid phase synthetic deletion product. On 5- or 10- μm microparticulate reversed phase columns, these peptides are readily resolved preparatively in less than twenty minutes with simple elution systems. The elution order is in accord with that expected on the basis of hydrophobic fragmental constant summation. These HPLC techniques have been extended to permit the analytical assessment of the isolation of bovine pro-insulin and the proinsulin intermediates. The conversion of bovine proinsulin initially to the intermediates and finally to the desalanyl-insulin and the C-peptide on tryptic digestion can be followed by HPLC techniques which thus supplement alternative polyacrylamide disc electrophoretic methods.     

Analysis of Plasma Angiotensins by Reversed Phase HPLC and Radioimmunoassay

Abstract

The analysis of biologically active angiotensin peptides in blood plasma by high performance liquid chromatography in a weakly non-polar reversed phase (C₂) chromatographic system combined with quantification of chromatographically isolated peptides by radioimmunoassay has been developed. This system is able to resolve each of seven closely-related peptides of the angiotensin group. The chromatographic system was applied to plasma samples which have been prepared for chromatographic analysis by C₁₈ cartridge extraction. Samples were reconstituted in HPLC solvent prior to injection into the HPLC system. Separated angiotensin were collected by fraction collector and the volatile components of the solvent system were blown off under an air stream. The content of several of the various angiotensin peptides in the fractions was then determined by radioimmunoassay using an appropriate antiserum. Antiserum to angiotensin II (octapeptide) was used to quantify the biologically active components angiotensin II, angiotensin III (hepta-peptide) and C-terminal hexapeptide. Recovery of angiotensin II in the C₁₈ cartridge extraction has been assessed at 85.0 ± 0.9% (mean ± SEM) using I¹²⁵-labelled angiotensin II, and 82.2 ± 4.45% using synthetic unlabelled angiotensin II. Recovery of standard preparations of angiotensin II in the HPLC system have been estimated at 67.5 ± 6.08%. The application of this technique to evaluating some components of the angiotensin in normal plasma is presented.     

Chromatography of Trichothecene Mycotoxins

Abstract

Trichothecene mycotoxins occur in agricultural commodities and can cause problems from feed refusal to death in animals. This paper describes chromatographic methods for selective analysis for trichothecene mycotoxins. These methods include gas chromatography (GC), thin layer chromatography (TLC), and high pressure liquid chromatography (HPLC). The trichothecene analysis methods by GC and TLC are shown to have a greater sensitivity than in HPLC for the underivatized mycotoxins.     

剖析液相色谱柱技术的复杂状况(英文)

 Column packings continue to evolve as the needs of users for high efficiency, high resolution and highly sensitive high performance liquid chromatographic (HPLC) analysis drive further developments. In comparing and contrasting modern HPLC columns technologies, diameters of column packings and particle materials are covered. Some products and applications of modern HPLC columns are provided. Future directions in packing developments are predicted in this introductory article.     

High Pressure Liquid Chromatography of Thyromimetic Iodoamino Acids

Abstract

The chromatographic properties of 16 thyromimetic iodoamino acids and related compounds on microparticulate non-polar stationary phases have been examined and conditions determined which allow optimised resolution with analysis time ca. 60 minutes. These compounds elute in order of increasing hydrophobicity which correlates with the progressive increase in the number of iodogroups present in the tyrosine or thyronine aromatic nucleus. The reverse isomers, e.g. rT3, have consistently greater k' values than their corresponding analogues, e.g. T3. Conditions for the direct application of the rapid HPLC analyses of the iodoamino acids in biological or pharmaceutical samples have been examined.     

Overpressured Thin-Layer Chromatography and Its Applications

Abstract

In recent years, a rapid progress can be observed both in column and planar liquid chromatographic techniques. In the field of liquid column chromatography the most spectaular achievement was the development of high-performance liquid chromatographic/HPLC/ systems by means of several special instruments and sorbents/1, 2/. As regards planar techniques, the most significant break-through is the development of highperformance thin-layer chromatography/HPTLC//3/ based on the application of fine-particle sorbents. Both techniques proved to be very useful in many fields of chemical analysis, although the use of the latter is more restricted, mainly to micro chromatographic studies.     

Determination of Flecainide in Human Plasma by High Performance Liquid Chromatography with Fluorescence Detection

Abstract

A simple, rapid, selective, and sensitive high-performance liquid chromatographic (HPLC) method for the monitoring of plasma flecainide levels in a therapeutic or research environment is described. The drug is first separated from plasma by a single-step extraction with hexane and then quantitated by HPLC with fluorescence detection. Two linear ranges have been established; 100–2000 ng/ml for drug monitoring in clinical management of patients and 3–300 ng/ml for pharmacokinetic studies. The intra-day variation is less than 6%.     

Hair Colors: Classification,Chemistry and a Review of Chromatographic and Electrophoretic Methods for Analysis

Abstract

At present, the demand for hair color is rising globally. Because commercial hair colors have been reported to possess adverse effects on human health, their formulation is under strict regulation in each country. In this review, we briefly discuss the advantages and limitations of currently available chromatographic and electrophoretic methods, such as high performance liquid chromatography (HPLC), gas chromatography/gas chromatography with mass spectrometry (GC/GC-MS), and capillary electrophoresis (CE) employed for the analysis of dyestuffs present in commercial hair colors. Furthermore, a brief attempt has been made to classify hair colors according to their type and stability on hair. In addition, the chemistry behind dyeing is also briefly surveyed.     

Application of Computer-Aided Spectral Deconvolution Technique in Validation of High Performance Liquid Chromatographic Peaks

Abstract

Reliable analysis with high performance liquid chromatography (HPLC) requires purity of the eluting peak. The present work has combined the advantages of the availability of full spectral data from HPLC photodiode array UV detector and computer algorithms to perform chromatographic peak purity check. A deconvolution technique based on multicomponent analysis has been applied to the UV spectra of co-eluting components. This method employs residual error (Relative-fit-error, RFE) between predicted spectrum and analyte's spectrum to detect presence of other component or contaminant. Typical RFE values for uncontaminated chromatographic peaks of norethisterone and ethynyloestradiol range between 1 and 3, while contaminated peaks have RFE values as large as 145. A systematic increase in ‘relative-fit error’ from 1.10 to 145 was observed for peaks of norethisterone when contaminated to varied extent with ethynyloestradiol. Extent of peak overlap in chromatogram was also mapped out with this technique. The co-prescribed oral contraceptive, norethisterone and ethynyloestradiol were used as model in this work. An advantage of the method is its applicability when the contaminant's spectrum is unavailable. The method, unlike several earlier techniques, is also applicable to chromatograms with concidental elution time for the components.     

The Simultaneous Spectrophotometric Assay of the Active Constituents of Multicomponent Analgesics Using Kalmanfiltering

Abstract

UV-spectrophotometry in combination with Kalmanfiltering is used for the assay of analgesics in tablets. Commercial products containing various combinations of acetylsalicylic acid, salicylic acid, caffeine, phenacetine and acetaminophen are analyzed. For comparison, these tablets were also analyzed by HPLC. The accuracy and precision of both methods are comparable. The described spectrophotometric assay with the aid of Kalmanfiltering represents a new, rapid and low-cost alternative to existing analytical procedures for analgesics.     

Quantitative HPLC Analysis of Plasma Amino Acids as Orthophthaldialdehyde/Ethanethiol Derivatives

Abstract

A reverse phase high performance liquid chromatographic method for the analysis of plasma amino acids is described. The method employs pre-column derivatization with o-phthaldialdehyde using ethanethiol as the reducing agent. The analysis shows good linearity and reproducibility. An average overall difference of 12% was seen for results obtained by the HPLC method versus those obtained with an amino acid analyzer. The chromatographic parameters of buffer concentration and column temperature were also examined.     

Liquid Crystals as Stationary Phases for High Performance Liquid Chromatography

Abstract

Liquid crystals have not yet been used as stationary phases in High Performance Liquid Chromatography. This is surprising since Gas Chromatography has demonstrated some remarkable separations, many of which are not possible with normal stationary phases, that have been achieved where liquid crystals have been employed as the stationary phase. The objective of the work reported here was to evaluate the chromatographic properties of several cholesteric liquid crystals as stationary phases in HPLC. Included in this study was an investigation of the feasibility of bonding a cholesteric moiety to a solid support for use in HPLC. The columns showed a dramatic increase in capacity factor for steroid molecules as the temperature of the column was increased.     

Improved High Performance Liquid Chromatography of Cyclic Polypeptide Antibiotics—Polymyxins B—and Its Application to Assays of Pharmaceutical Formulations

Abstract

An isocratic high performance liquid chromatographic (HPLC) method for the analysis of polymyxins B1 and B2 is described. The method uses a 25 cm Hypersil—ODS column, a mobile phase containing 22.5% acetonitrile (v/v) in an aqueous phase with tetramethylammonium chloride (TMAC), a flow rate of 1.09 ml/minute and a wavelength of 220 nm for detection. Complete resolution of B1 and B2, and their separation from all other components and/or impurities have been achieved in less than 23 minutes. The capability of the method for the determination of the polymyxin content in pharmaceutical preparations has also been demonstrated.     

Determination of Lipophilic Character of a Series of Dermorphin-Related Oligopeptioes by Means of Reversed-Phase HPLC

Abstract

In recent times there has been a growing interest in the determination of chromatographic parameters of lipophilicity with regard to their use in the study of quantitative structure-activity relationship (1, 2). Very good correlations had been shown between the chromatographic parameters and the log P or π values as a measure of the partition coefficient between octanol and water (2). The reversed phase TLC R_m values in two different chromatographic systems and the reversed-phase HPLC log k′ values of a series of dermorphin-related oligopeptides have been previously determined (3, 4). The purpose of the present work was to study the relationship between log k′ values on one hand and R_m or ^Σπ values on the other one in view of QSAR studies. In fact the discovery of enkephalin and endorphins with high affinities for opioid receptors added new dimensions to the study of structure-activity relationship of opioid agonists (5, 6, 7, 8).     

High-Performance Liquid Chromatographic Determination of Lasalocid Sodium in Chicken Tissue

Abstract

A high-performance liquid chromatographic (HPLC) method with fluorometric detection has been developed to determine lasalocid sodium(Fig.1) residues in chicken tissues. Lasalocid sodium was extracted from tissues by homogenizing them with methanol, purified by silicagel cartridge column and separated by HPLC using an ODS column.     

Extraction of Anthracyclines from Biological Fluids for HPLC Evaluation

Abstract

A new technique for the extraction of anthracyclines and their metabolites from plasma or serum is described, which gives suitable extracts for HPLC analysis of these drugs in patients. This technique consists in a very rapid chromatographic step on the bonded silica contained in small open columns (C-18 Sep-Paks, Waters Associates). This extraction gives quantitative recoveries of all the anthracyclines and metabolites that have been tested; 0.2 to 3 ml of plasma can be processed, with concentrations up to 5,000 ng/ml. The advantages of this technique over classical techniques using an organic extraction with a partition between two phases are: speed, simplicity, efficacy, reproducibility and similarity of recoveries for various anthracyclines.     

High-Performance Liquid Chromatographic Determination of Trace Quantities of Azinphos Methyl and Azinphos Methyl Oxon in Various Water Sources by Direct Injection and Trace Enrichment

Abstract

A high-performance liquid chromatographic (HPLC) method is described for the determination of trace amounts of the organophosphate insecticide, azinphos methyl and its degradation product, azinphos methyl oxon, by direct injection and by trace enrichment. The compounds were analyzed on a uBondapak C₁₈ column with UY detection at 224 nm. The mobile phase for the analysis was acetonitrile-water (50:50) at a flow rate of 1.3 ml/min. Ten minutes were required for the chromatographic analysis. Water from three sources, public water supply, stream, and ocean was analyzed for azinphos methyl and azinphos methyl oxon at concentrations as low as 11.9 and 11.3 ppb, respectively, without a clean-up, concentration or derivatization step. Azinphos methyl was quantitated at 0.29 ppb and azinphos methly oxon at 0.29 ppb by employing a concentration step involving a C₁₈ Sep-Pak cartridge. The coefficients of variation for all determinations ranged from 0.77 to 9.06%. Peak heights were used for quanti-tation. Several other pesticides have been shown not to interfere with the analysis of either compound.     

Retention Behavior of Benzodiazepines in Normal-Phase HPLC. Silica,Cyano, and Amino Phases Comparison

Abstract

The retention data for 16 benzodiazepines was evaluated on different normal-phase HPLC columns using the Soczewinski-Snyder model. The slopes and intercepts of the linear relationships between log k' and the mobile phase composition have been discussed in relation to solute and stationary phase characteristics. The good correlation between substituent chromatographic contribution and substituent electronic constant showed that the benzodiazepine molecule acts as a proton donor towards the adsorbent sites of the stationary phases investigated.