Simultaneous determination of naproxen and related compounds by HPLC using porous graphitic carbon column (original) (raw)
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Journal of Chromatography A, 2007
The main tests developed in last 20 years to investigate the chromatographic behaviour and the stationary phase properties are described in this paper. These properties are the hydrophobicity, depending on the surface area and the bonding density, the number of accessible residual silanol groups having sometimes different acidity, which can interact with neutral solutes by hydrogen bonds or with the ionic form of basic compounds and the shape or steric selectivity, depending on both the functionality of the silanising agent and the bonding density. Two types of tests are performed, either based on key solutes having well defined properties such as phenol, caffeine, amitriptyline, benzylamine, acenaphtene, o-terphenyl, triphenylene, p-ethylaniline, carotenoid pigments, or on retention models (solvation parameter, hydrophobic subtraction) obtained from the analyses of numerous and varied compounds. Thus, the chromatographic properties are either related to selectivities or retention factors calculated from key solutes, or they are described by interaction coefficients provided by multilinear regression from retention models. Three types of comparison methods are used based on these data. First, simple plots allow the study of differences between the columns as regards to one or two properties. Columns located in the same area of the plot display close properties. Second, chemometric methods such as principal component analysis (PCA) or hierarchical cluster analysis (HCA) can be performed to compare columns. In this case, all the studied properties are included in the comparison, done either by data projection to reduce the space in which the information is located (PCA) or by distance calculation and comparison for drawing a classification (HCA). Neighbouring columns are expected to provide identical chromatographic performances. These two chemometric methods can be used together, PCA before HCA. The third way is to calculate a discrimination factor from a reference column, through calculation methods based on the Pythagorean Theorem: the lower this factor, the closer the column properties. Following the presentation of the analytical conditions, the compounds and the data treatments used by the teams working in this field, the pertinence of the different selectivities, i.e. of the different probe solute couples or of the different interaction coefficients, are discussed as regards their discrimination capacity. The accuracy of chemometric treatments in the discrimination of stationary phases having different functionalities (octadecylsiloxane (ODS), cyano, fluorinated, phenyl, polar embedded group or "aqua" type) will be discussed, as well as their performances in the finer ODS discrimination. New two-dimensional plots, from data gained by different studies will be suggested, to improve the classification of stationary phases having different nature of bonded chains.
Chromatographia, 2000
An analytical methodlogy for the determination of organotin compounds (OTs) in aqueous matrices based on solid-phase extraction (SPE) followed by Grignard pentylation and gas chromatography-flame photometric detector (GC-FPD) determination was developed. Spiked OTs, mono-, di-and tributyltin (MBT, DBTand TBT); and mono-, di-and triphenyltin (MPhT, DPhT and TPhT)were pre-concentrated from aqueous samples as OT chlorides in two different sorbents. A macroporous copolymer containing either lipophilic divinylbenzene, hydrophilic N-vinylpyrrolidone or conventional hydrophobic octadecyl (C18) bonded silica were evaluated by using an automated off-line SPE system. Optimization of the SPE preconcentration included the presence of a complexing agent, sample pH, loading the sorbent with a complexing agent (tropolone), eluent type and volume, breakthrough volume and the sorbent mass. Recoveries of OTs in spiked water samples at 100 ng L -1 ranged from 70 to 90%. Detection limits for butyltin and phenyltin compounds ranged from 10 ng L -1 to 20 ng L -1. Automation of the SPE procedure provides a higher sample throughput in comparison with the use of conventional C18 disks. A new polymeric SPE sorbent evaluated provides higher recoveries, better sample capacities and higher reproducibility in comparison with conventional hydrophobic C18 silica cartridges, and also uses lower sorbent mass.
Characterization of chromatographic supports for the analysis of basic compounds
Journal of Separation Science, 2002
Characterization of chromatographic supports for the analysis of basic compounds Reversed-phase liquid chromatography (RP-HPLC) has become a powerful and widely employed technique for the analysis of a great variety of substances and, in particular, of basic compounds. These compounds are present in various areas. In pharmacy, 80% of drugs are estimated to possess a basic function. Basic compounds can strongly interact with free silanol groups on the surface of the silica particles. These ion exchange interactions produce peak tailing which affects resolution, sensitivity, and reproducibility. For these reasons, many new stationary phases have been designed to reduce access to silanol groups. The main problem facing the analyst is to effectively select the best column for a particular type of separation. In order to characterize and evaluate the properties of these packings, several tests are proposed in the literature, which can be divided into two main categories: general tests and particular tests. In this work, a particular test was developed for the characterization of base deactivated RP-HPLC stationary phases. For this purpose, a set of 14 basic test substances was selected and five different chromatographic supports were tested with three isocratic mobile phases. Furthermore, in order to undertake a complete characterization of these supports, batch and column reproducibility were also studied. Principal Component Analysis was applied to evaluate both the performance of the test compounds and of the stationary phases.
Chromatographia, 2001
Reversed-phase liquid chromatography (RP-HPLC) has become a powerful and widely employed technique in the separation and analysis of a great variety of compounds with different functionalities. The most common type of stationary phase for RP-H PLC consists of nonpolar, hydrophobic organic species (e.g., octyl, octadecyl) attached by siloxane bonds to the surface of a silica support. In the first part of this article, a description of the many beneficial properties that make porous silica the most employed support in RP-HPLC will be presented, starting from the synthesis of silica. It is noteworthy that the chromatographic properties of the final column are strictly correlated to the preparation type. A silica surface possesses a number of attractive properties, but also some drawbacks. Unreacted or residual silanols interact with basic compounds and can induce peak tailing, which means a loss in chromatographic performance. This problem has lead many manufacturers to produce stationary phases with reduced silanol activity which improve dramatically the peak shape of basic compounds. In the second part of this review, different approaches are proposed to obtain less reactive stationary phases.
Bangladesh Pharmaceutical Journal, 2015
A simple, sensitive and precise reversed phase high performance liquid chromatographic (RP-HPLC) method has been developed for the estimation of naproxen in pharmaceutical dosage forms. The method was developed using the mobile phase comprising of dibasic sodium phosphate buffer (Na 2 HPO 4 ) at pH 7.80 (adjusted by sodium hydroxide) and acetonitrile in the ratio of 70:30 (v/v) over C-18 column (250 x 4.6 mm, 5µm, Phenomenex Inc.) at ambient temperature. The flow rate was at 0.7 ml/min and the column washing was monitored by UV detector at 225 nm. The retention time of naproxen was 4.8 ± 0.1 min. The recovery was found to be >97% which is demonstrative of accuracy of the protocol. Inter-day and intra-day precision of the newly developed method were less than the maximum allowable limit (RSD% ≤ 2.0) according to ICH, USP and FDA guidelines. The method showed linear response with correlation coefficient (r 2 ) value of 0.9991. Therefore, the method was found to be accurate, reproducible, sensitive and less time consuming and can be successfully applied for routine analysis of naproxen in pharmaceutical formulations.
A novel stability-indicating normal phase liquid chromatographic (NP-LC) method was developed for the determination of purity of naproxcinod in the presence of its impurities and degradation products. This method is capable of separating all the related substances of naproxcinod along with its chiral and achiral impurities. This method can be also be used for the estimation of assay of naproxcinod. The method was developed using chiralpak IB (250mm×4.6mm, 5μm) column with immobilized stationary phase. n-Hexane, 2-propanol, acetonitrile and triflouro acetic acid in 97.5:2.5:0.0.2:0.2 (v/v/v/v) ratio was used as a mobile phase. The eluted compounds were monitored at 210 nm. naproxcinod was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. The degradation products were well resolved from main peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per International Co...