Selection of reversed-phase liquid chromatographic columns with diverse selectivity towards the potential separation of impurities in drugs (original) (raw)
Related papers
Journal of Pharmaceutical and Biomedical Analysis, 2012
In LC method development, the choice of suitable experimental conditions is often challenging for the analyst because of the huge diversity of stationary phases, mobile phase pH and organic modifiers, that could significantly alter the selectivity. The influence of these parameters on selectivity was experimentally tested in both RPLC and HILIC conditions for the analysis of 45 pharmaceutical compounds covering a wide range of physico-chemical properties. Principal component analysis (PCA) models were built to assess the resulting multivariate dataset. The complementarity between RPLC and HILIC was clearly demonstrated. The importance of mobile phase pH as one of the main experimental factors to be considered was confirmed. The RPLC and HILIC methods were thus employed for the analysis of a drug cocktail containing two substrates and their numerous desmethylated metabolites. All the compounds were finally resolved in both modes, with a very distinct elution order. In addition, the possibility to combine columns of different selectivity was highlighted using a column coupler setup and found to be extremely promising. The same type of experiments was also carried out for the impurity profiling of an antihistaminic drug. In this example, compounds of very distinct polarity were satisfactorily eluted in both RPLC and HILIC modes, using suitable conditions of pH and stationary phase. In conclusion, this study demonstrates the complementary and interest of RPLC and HILIC in the case of pharmaceutical method development.
Journal of Separation Science, 2003
Capillary liquid chromatography as a tool for separation of hydrophobic basic drugs. Relation between tests for column characterization and real analysis Two capillary columns for reversed phase (RP) capillary liquid chromatography (CLC), viz. Nucleosil 100 -5 C18 and LiChrosorb RP-select B, were characterized by the Walters test, i.e. the chromatographic test proposed for RP stationary phases. Hydrophobicity indices were determined not only in acetonitrile/water mobile phase, as proposed in the test, but they were also measured in buffered systems. This approach was used to quantify the influence of mobile phase composition on the modification of the surface of the stationary phases. In the next step, small basic compounds differing in their hydrophobicity and basicity were selected and their retention on the stationary phases in mobile phases of the same composition as used for column testing was examined. Furthermore, the retention of newly synthesized drugs, chemotherapeutics derived from thioacridine and pyridoquinoline, differing in their structures, basicity, and hydrophobicity, was also studied. The composition of the mobile phases had to be shifted to higher contents of organic modifiers -acetonitrile or methanol -in order to elute these hydrophobic compounds from the columns. The question we wanted to answer was: How is the method for testing of reversed phases related to retention, separation efficiency, and peak symmetry of various analytes?
Journal of Chromatography A, 2009
In this paper a comparison of two column characterisation systems is reported: the method based on the hydrophobic-subtraction model of Dolan and Snyder (HS method) versus the method developed at the Katholieke Universiteit Leuven (KUL method). Comparison was done for seven different pharmaceutical separations (fluoxetine, gemcitabine, erythromycin, tetracycline, tetracaine, amlodipine and bisacodyl), using a set of 59 columns. A ranking was built based on an F value (KUL) or F s value (HS) versus a (virtual) reference column. Both methods showed similar probabilities of ranking patterns. Correlation of the respective test parameters of both approaches was poor. Both methods are not perfect and do not match well, but anyhow yield results which allow, with a relatively high certainty, the selection of similar or dissimilar columns as compared to a reference column. An analyst that uses either of the two methods will end up with a similar probability to choose an adequate column. From a practical point of view, it must be noted that the KUL method is easier to use.
Journal of Separation Science, 2012
Recent developments in HPLC methods have focused on various strategies in order to increase the speed of analysis. One area of impressive growing is column technology. Today, analytical methods that propose the use of short columns packed with sub-2 mm particles installed in ultra high-pressure LC instruments are not uncommon. Another strategy consisted of heating thermally resistant columns to temperatures well above of 1001C in order to reduce eluent viscosities and, therefore, column backpressure. We discuss experimental conditions for achieving high-throughput analysis using standard instruments with a few simple modifications. The chromatographic performance of two particulated and a silica-based monolithic column operated at moderate temperatures and flow rates are compared. The monolithic column proved to be stable over several thousands column volumes at 601C. More important, its resistance to mass transfer at this temperature was significantly reduced. Very fast separations of two different mixtures of pharmaceutical compounds, anti-inflammatory drugs and b-blockers, were achieved with the three columns at 601C by using ACN/buffer at 5 mL/min. Excellent peak shapes of basic solutes and quite reasonable resolutions were achieved in very short analysis times with columns operated at temperatures moderately higher than the usual room temperature.
Journal of Chromatographic Science, 2000
Retention data for a set of 69 compounds using rapid gradient elution are obtained on a wide range of reversed-phase stationary phases and organic modifiers. The chromatographic stationary phases studied are Inertsil (IN)-ODS, pentafluorophenyl, fluoro-octyl, n-propylcyano, Polymer (PLRP-S 100), and hexylphenyl. The organic solvent modifiers are 2,2,2trifluoroethanol (TFE); 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP); isopropanol; methanol (MeOH); acetonitrile (AcN); tetrahydrofuran; 1,4-dioxane; N,N-dimethylformamide; and mixed solvents of dimethylsulfoxide (DMSO) with AcN and DMSO with MeOH (1:1). A total of 25 chromatographic systems are analyzed using a solvation equation. In general, most of the systems give reasonable statistics. The selectivity of the reversed phase-highperformance liquid chromatographic (HPLC) systems with respect to the solute's dipolarity-polarity, hydrogen-bond acidity, and basicity are reflected in correspondingly large coefficients in the solvation equation. We wanted to find the most orthogonal HPLC systems, showing the highest possible selectivity difference in order to derive molecular descriptors using the gradient retention times of a compound. We selected eight chromatographic systems that have a large range of coefficients of interest (s, a, and b) similar to those found in water-solvent partitions used previously to derive molecular descriptors. The systems selected are IN-ODS phases with AcN, MeOH, TFE, and HFIP as mobile phase, PLRP-S 100 phase with AcN, propylcyano phase with AcN and MeOH, and fluorooctyl phase with TFE. Using the retention data obtained for a compound in the selected chromatographic systems, we can estimate the molecular descriptors with the faster and simpler gradient elution method.
AdvionInterchim Scientific, 2023
When replacing a column for a separation under partially aqueous reversed-phase conditions, few problems may arise. This column may still not be available. A new column with the same designation may not provide the same separation. Several attempts have been made to produce a set of chemical probes to best characterize the huge number of stationary phases available. Nowadays a harmonized set of test probes has not been identified. However several independent publicly databases of HPLC columns exist today. They were also used for selection of alternative columns giving very different selectivities. We present, here, a new and complementary ranking method which includes flash purification, preparative LC and core-shell columns.The new and complementary ranking method was obtained from the sum of respective Euclidean differences corresponding to 6 normalized parameters. Four of them are the well-known Tanaka selectivities: C/P), (T/O), (A/P) pH 2.7, (A/P) pH 7.6. The fifth is the hydrophobic potential HP. The sixth parameter is the symmetry d(TF; 1) derived from reduced Veuthey test methodology at basic pH. For evaluation of the stationnary phase similarity they have been in parallel characterized by a normalized radar plot drawn with the four parameters: HP, alphaC/P), alpha(T/O), alpha(A/P) pH 2.7 and two histograms (normalized retention capacity and symmetry parameter).
Journal of Pharmaceutical and Biomedical Analysis, 1995
Prednisolone, an important active pharmaceutical ingredient, is a synthetic glucocorticoid used for the preparation of various pharmaceutical products with anti-inflammatory and immunosuppressive properties. It is a challenge in high-performance liquid chromatography (HPLC) to separate the prednisolone peak and its structurally related substance (hydrocortisone), which only differs in a double bond at the C-1 position. Successful application of the HPLC method according to the European Pharmacopoeia monograph for related substances of prednisolone is very often limited to the chromatographic system available. This is due to the nonbaseline separation of the prednisolone and hydrocortisone peaks, which is strongly influenced by the instrument parameters and the chosen C18 column. First, an adjusted European Pharmacopoeia method for related substances of prednisolone was developed within the allowable adjustments. Next, an improved stabilityindicating reversed-phase HPLC method for related substances of prednisolone was developed and validated for use in quality control laboratories for routine analysis. The optimized separation was performed on a Phenomenex Gemini C18 column (150 mm × 4.6 mm, 3 μm) using a gradient mobile-phase system consisting of acetonitrile/tetrahydrofuran/water (15:10:75 v/v/v), acetonitrile/water (80:20 v/v), and ultraviolet detection at 254 nm. A baseline separation was achieved, and stability indicating capability was demonstrated by a forced degradation study. A full validation procedure was performed in accordance with International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines.
Journal of Chromatography A, 1999
Quantitative structure-retention relationships (QSRRs) were derived for logarithms of retention factors normalised to a hypothetical zero percent organic modifier eluent, log k , determined on 18 reversed-phase high-performance liquid w chromatography (RP-HPLC) columns for 25 carefully designed, structurally diverse test analytes. The study was aimed at elucidating molecular mechanism of retention and at finding an objective manner of quantitative comparison of retention properties and classification of modern stationary phases for RP-HPLC. Three QSRR approaches were employed: (i) relating log k to logarithms of octanol-water partition coefficient (log P); (ii) describing log k in terms of linear solvation-energy w w relationship-based parameters of Abraham; (iii) regressing log k against simple structural descriptors acquired by w calculation chemistry. All the approaches produced statistically significant and physically interpretable QSRRs. By means of QSRRs the stationary phase materials were classified according to the prevailing intermolecular interactions in the separation process. Hydrophobic properties of the columns tested were parametrized. Abilities of individual phases to provide contributions to the overall retention due to non-polar London-type intermolecular interactions were quantified. Measures of hydrogen-bond donor activity and dipolarity of stationary phases are proposed along with two other phase polarity parameters. The parameters proposed quantitatively characterize the RP-HPLC stationary phases and provide a rational explanation for the differences in retention patterns of individual columns observed when applying the conventional empirical testing methods.
Chemometric classification of reversed-phase high-performance liquid chromatography columns
Journal of Chromatography A, 1987
Cluster analysis and principal components analysis have been used to classify nine octadecyl (C,a) high-performance liquid chromatography (HPLC) columns into three general groups displaying similar chromatographic behaviour. Principal components analysis was also able to identify the key test compounds on which the classification was most highly dependent. These identifications agreed with the classification and test compound selection by an HPLC specialist. In addition, the chemometric techniques can easily be extended to many more columns and test measurements than could be conveniently examined by a human expert.