Separation Of Nonsteroidal Anti-inflammatory Drugs Research Articles

A mixed-mode reversed-phase/strong-anion-exchange stationary phase: Analyte-retention stability and application in the analysis of nonsteroidal anti-inflammatory drugs

Mixed-mode reversed-phase/anion-exchange chromatography (RP/AEX) is an effective method for the chromatographic analysis of acidic drugs because it combines reversed-phase chromatography (RP) with anion-exchange chromatography (AEX). However, the result repeatability for the RP/AEX analysis of acidic drugs is frequently compromised by the detrimental effects of residual silanol groups in an RP/AEX stationary phase on peak separation and analyte retention. In this study, an RP/weak-AEX stationary phase with amino anion-exchange groups, Sil-AA, was prepared. Subsequently, an RP/strong-AEX stationary phase, Sil-PBQA, was prepared by replacing the amino groups in Sil-AA with a benzene ring and a benzyl-containing quaternary ammonium salt. The chromatographic behaviors of Sil-PBQA and Sil-AA were compared, and the effect of residual silanol groups on the chromatographic behavior of an RP/AEX stationary phase was evaluated. Residual silanol groups not only caused additional electrostatic interactions for acidic analytes, but also competed with the analytes for the anion-exchange sites in an RP/AEX stationary phase. The effects of different salt-containing mobile-phase systems on the analyte-retention behavior of Sil-PBQA were investigated to develop a method that enhanced the repeatability of the RP/AEX acidic-analyte-analysis results obtained using Sil-PBQA and facilitated the separation of nonsteroidal anti-inflammatory drugs on Sil-PBQA. The ideas presented in this paper can improve the separation of peaks and repeatability of results in the RP/AEX analysis of acidic drugs.

Tandem-Column High Performance Liquid Chromatography Separation of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

Tandem-Column High Performance Liquid Chromatography Separation of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

Response Surface Method for Simultaneous Separation of Non-Steroidal Anti-Inflammatory Drugs and Tetracyclines in Water Samples using Online Solid Phase Extraction-Liquid Chromatography

Response Surface Method for Simultaneous Separation of Non-Steroidal Anti-Inflammatory Drugs and Tetracyclines in Water Samples using Online Solid Phase Extraction-Liquid Chromatography

Dynamic in situ growth of bonded-phase silica nanospheres on silica capillary inner walls for open-tubular liquid chromatography

Silica nanospheres (SNS) were grown on the inner walls of silica capillaries through a dynamic in situ nucleation process to prepare a highly porous and large accessible surface area substrate. The SNS were then functionalized with octadecyl (C18), 3-aminopropyltriethoxysilane (APTES), beta-cyclodextrin (β-CD), and amino groups to develop robust and efficient chromatographic stationary phases. The modified silica capillaries were exploited for open-tubular liquid chromatography (OT-LC) and open-tubular capillary electrochromatography (OT-CEC) applications. The prepared stationary phases were compared to conventional capillaries in terms of separation performance. The synthesis process was optimized, and the bonded-phase stationary phases were characterized by the electron microscopy technique. The effects of different solvents, additives, and functional groups on the geometry and chromatographic resolving power of the SNS were envisaged. The capillaries modified with octadecyl groups were evaluated for the separation of non-steroidal anti-inflammatory drugs, phenones, alkenylbenzenes, and enantiomers of chlorophenoxy herbicides. As an application instance, an SNS-C18-coated capillary was utilized for the separation of alkenylbenzenes from clove extract and protein digest medium, through OT-LC and OT-CEC techniques, respectively. The β-CD functionalized capillary was applied for the OT-CEC separation of a dichlorprop racemic mixture.Graphical abstract

Enantioselective separation of nonsteroidal anti-inflammatory drugs with amylose tris(3-chloro-5-methylphenylcarbamate) stationary phase in HPLC with a focus on enantiomeric quality control in six pharmaceutical formulations containing racemic mixtures or single stereoisomers.

In the present study, an accurate, rapid, and simple chiral HPLC-UV method with amylose tris(3-chloro-5-methylphenylcarbamate) as stationary phase was developed and applied for enantiomeric determination of six nonsteroidal anti-inflammatory drugs (NSAIDs) in the commercial pharmaceutical formulations, including (R,S)-ibuprofen, S-ibuprofen, (R,S)-ketoprofen, S-ketoprofen, S-naproxen, and (R,S)-loxoprofen sodium. Experiments on the influence of mobile phase composition, proportion of organic modifier, percentage of acid additives, and column temperature on enantioseparation were conducted to obtain the best separation condition. It was indicated that one mobile phase simply composed of acetonitrile-water (0.1% formic acid, v/v) at the proportion of 50:50 (v/v) with a flow rate of 0.6ml/min at 22°C could simultaneously provide the excellent enantiomeric resolutions for all selected NSAIDs, which made the enantioseparation process more applicable and operable. The newly developed method was then applied for determination of NSAID enantiomers in pharmaceutical formulations containing racemic mixtures or single stereoisomers. Calibration curve of each enantiomer at the concentration of 5.0-100 ug/ml showed good linearity with the correlation coefficient above 0.9996. Satisfactory recovery (96.54-101.54%), good intra-day precision (RSD 0.52-1.46%), and inter-day precision (RSD 0.13-1.09%) were also obtained. The newly developed method was then applied for determination of NSAID enantiomers in pharmaceutical formulations containing racemic mixtures or single stereoisomers. Quantitative results of the commercial capsules and tablets demonstrated that the difference between the declared and measured values did not exceed 1.52%.

Polycaprolactone Composite Micro/Nanofibrous Material as an Alternative to Restricted Access Media for Direct Extraction and Separation of Non-Steroidal Anti-Inflammatory Drugs from Human Serum Using Column-Switching Chromatography.

Application of the poly-ɛ-caprolactone composite sorbent consisting of the micro- and nanometer fibers for the on-line extraction of non-steroidal anti-inflammatory drugs from a biological matrix has been introduced. A 100 μL human serum sample spiked with ketoprofen, naproxen, sodium diclofenac, and indomethacin was directly injected in the extraction cartridge filled with the poly-ɛ-caprolactone composite sorbent. This cartridge was coupled with a chromatographic instrument via a six-port switching valve allowing the analyte extraction and separation within a single analytical run. The 1.5 min long extraction step isolated the analytes from the proteinaceous matrix was followed by their 13 min HPLC separation using Ascentis Express RP-Amide (100 × 4.6 mm, 5 µm) column. The recovery of all analytes from human serum tested at three concentration levels ranged from 70.1% to 118.7%. The matrix calibrations were carried out in the range 50 to 20,000 ng mL−1 with correlation coefficients exceeding 0.996. The detection limit was 15 ng mL−1, and the limit of quantification corresponded to 50 ng mL−1. The developed method was validated and successfully applied for the sodium diclofenac determination in real patient serum. Our study confirmed the ability of the poly-ɛ-caprolactone composite sorbent to remove the proteins from the biological matrix, thus serving as an alternative to the application of restricted-access media.

Enantioselective Separation of Nonsteroidal Anti-Inflammatory Drugs with Amylose Tris (3-Chloro-5-Methylphenylcarbamate) Stationary Phase in HPLC with a Focus on Enantiomeric Quality Control in Six Pharmaceutical Formulations Containing Racemic Mixtures or Single Stereoisomers

In the present study, an accurate, rapid and simple chiral HPLC-UV method with amylose tris (3-chloro-5-methylphenylcarbamate) as stationary phase was developed and applied for enantiomeric determination of six nonsteroidal anti-inflammatory drugs (NSAIDs) in the commercial pharmaceutical formulations, including Rac-ibuprofen, S-ibuprofen, Rac-ketoprofen, S-ketoprofen, S-naproxen and Rac-loxoprofen sodium. Experiments on the influence of mobile phase composition, proportion of organic modifier, percentage of acid additives as well as column temperature on enantioseparation were conducted to obtain the best separation condition. It was indicated that one mobile phase simply composed of acetonitrile-water (0.1% formic acid) at the proportion of 50:50 (v/v) with a flow rate of 0.6 mL/min at 22℃ could simultaneously provid the excellent enantiomeric resolutions for all selected NSAIDs, which made the enantioseparation process more applicable and operable. The newly developed method was then applied for determination of NSAID enantiomers in pharmaceutical formulations containing racemic mixtures or single stereoisomers. Calibration curve of each enantiomer at the concentration of 5.0－100 ug/ml showed good linearity with the correlation coefficient above 0.9996. Satisfactory recovery (96.54－101.54%), good intra-day precision (RSD 0.52－1.46%) and inter-day precision (RSD 0.13－1.09%) were also obtained. Quantitative results of the commercial capsules and tablets demonstrated that the difference between the declared and measured values did not exceed 1.52%.

Adjusting the chromatographic properties of poly(ionic liquid)‐modified stationary phases by substitution on the imidazolium cation

Poly(ionic liquid)-modified stationary phases can have multiple interactions with solutes. However, in most stationary phases, separation selectivity is adjusted by changing the poly(ionic liquid) anions. In this work, two poly(ionic liquid)-modified silica stationary phases were prepared by introducing the cyano or tetrazolyl group on the pendant imidazolium cation on the polymer chains. Various analytes were selected to investigate their mechanism of retention in the stationary phases using different mobile phases. Two poly(ionic liquid)-modified stationary phases can provide various interactions toward solutes. Compared to the cyano-functionalized poly(ionic liquid) stationary phase, the tetrazolyl-functionalized poly(ionic liquid) stationary phase provides additional cation-exchange and π-π interactions, resulting in different separation selectivity toward analytes. Finally, applicability of the developed stationary phases was demonstrated by the efficient separation of nonsteroidal anti-inflammatory drugs.

Green synthesis of mesoporous molecular sieve incorporated monoliths using room temperature ionic liquid and deep eutectic solvents

A hybrid monolith incorporated with mesoporous molecular sieve MCM-41 of uniform pore structure and high surface area was prepared with binary green porogens in the first time. With a mixture of room temperature ionic liquids and deep eutectic solvents as porogens, MCM-41 was modified with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS) and the resulting MCM-41-MPS was incorporated into poly (BMA-co-EDMA) monoliths covalently. Because of good dispersibility of MCM-41-MPS in the green solvent-based polymerization system, high permeability and homogeneity for the resultant hybrid monolithic columns was achieved. The MCM-41-MPS grafted monolith was characterized by scanning electron microscopy, energy dispersive spectrometer area scanning, transmission electron microscopy, FT-IR spectra and nitrogen adsorption tests. Chromatographic performance of MCM-41-MPS grafted monolith was characterized by separating small molecules in capillary electrochromatography, including phenol series, naphthyl substitutes, aniline series and alkyl benzenes. The maximum column efficiency of MCM-41-MPS grafted monolith reached 209,000 plates/m, which was twice higher than the corresponding MCM-41-MPS free monolith. Moreover, successful separation of non-steroidal anti-inflammatory drugs and polycyclic aromatic hydrocarbons demonstrated the capacity in broad-spectrum application of the MCM-41-MPS incorporated monolith. The results indicated that green synthesis using room temperature ionic liquid and deep eutectic solvents is an effective method to prepare molecular sieve-incorporated monolithic column.

Preparation, characterization and application of a reversed phase liquid chromatography/hydrophilic interaction chromatography mixed-mode C18-DTT stationary phase

A mixed-mode chromatographic stationary phase, C18-DTT (dithiothreitol) silica (SiO2) was prepared through “thiol-ene” click chemistry. The obtained material was characterized by fourier transform infrared spectroscope, nitrogen adsorption analysis and contact angle analysis. Chromatographic performance of the C18-DTT was systemically evaluated by studying the effect of acetonitrile content, pH, buffer concentration of the mobile phase and column temperature. It was demonstrated that the novel stationary phase possessed reversed phase liquid chromatography (RPLC)/hydrophilic interaction liquid chromatography (HILIC) mixed-mode property. The stop-flow test revealed that C18-DTT exhibited excellent compatibility with 100% aqueous mobile phase. Additionally, the stability and column-to-column reproducibility of the C18-DTT material were satisfactory, with relative standard deviations of retention factor of the tested analytes (verapamil, fenbufen, guanine, tetrandrine and nicotinic acid) in the range of 1.82–3.72% and 0.85–1.93%, respectively. Finally, the application of C18-DTT column was demonstrated in the separation of non-steroidal anti-inflammatory drugs, aromatic carboxylic acids, alkaloids, nucleo-analytes and polycyclic aromatic hydrocarbons. It had great resolving power in the analysis of various compounds in HILIC and RPLC chromatographic conditions and was a promising RPLC/HILIC mixed-mode stationary phase.

An investigation into the stability of microemulsions in electrophoresis.

A typical oil-in-water microemulsion (ME) was applied for the capillary electrophoretic separation of nonsteroidal anti-inflammatory drugs (NSAIDs). As the high-pH ME was introduced into the capillary and a voltage was applied, we observed an unusual phenomenon during the preconditioning process: a sharp inflection point occurred at 56.2 min ( ± 4.8%) (N = 15). Both before (region A) and after (region B) that point, a steady state was observed. Highly reproducible results were obtained for this event. Two different absorbance patterns were observed for the hydrostatic injection of either freshly prepared ME or ME collected from the outlet of the capillary column during the steady state of region B. The latter had an inflection point at approximately 9 min, whereas the former had a constant absorbance over the entire range. To further characterize this property, regions A and B were used for the separation of NSAIDs. The results showed that both the detection limit and the reproducibility of the separation were superior in region B. For deep insight into the stability of the ME in an electric field, the effects of the oil, cosurfactant, pH, and voltage were systematically investigated in the neat ME. From our findings, it can be concluded that the inflection time might be the migration time of the ME in an electric field, and it might actually be the result of equilibration. Moreover, the existence of many unexpected phenomena seems to be the result of a change in the properties of ME droplet in an electric field.

High-performance Enantiomer Separation of Nonsteroidal Anti-inflammatory Drugs (NSAIDs) by 3 μm Reversed-phase Chiral Columns and Application to the Optical Purity Testing of Naproxen Drug Substances and Its Formulations

The enantiomer separation of five nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, ketoprofen (KP) and naproxen (NX), which are included in The Japanese Pharmacopoeia 16th edition (JP16), was investigated by employing four kinds of 3 μm reversed-phase chiral columns (AD-3R, AS-3R, OD-3R and OJ-3R). Except for KP, the enantiomers of four NSAIDs were successfully separated by one of the four columns. Among five NSAIDs, only NX has been used as a single enantiomer (S-form, active form) in the clinical field (JP16); therefore, optical purity testing method of NX is required for its quality evaluation. Among four CSPs, the method was developed by using an AS-3R column, which showed good enantioselectivity for NX enantiomers. By optimizing the conditions, the resolution (Rs) of 2.55 was obtained for NX enantiomers within approximately 6 min. The minor enantiomer R-form eluted before the main active enantiomer S-form. Finally, the developed method was applied to the optical purity testing of NX active pharmaceutical ingredients (APIs), and its formulations (tablet and capsule). Other than the minor enantiomer (R-form, inactive form, 0.21 - 0.78%), normal (not chiral) impurities at levels of 0.01-0.3% were simultaneously separated and determined by the method, showing an excellent separation capability of the method for those impurities including the minor enantiomer. The content uniformity test of the NX tablet according to JP16 was also successfully performed by the method with the AS-3R column. Normal phase separation with two chiral columns (AD-H and OD-H) and capillary electrophoretic (CE) separation were also investigated for five NSAIDs enantiomers to discuss the enantioselectivity.

Functionalized carbon nanotubes as the pseudostationary phase for capillary EKC separation of non‐steroidal anti‐inflammatory drugs

Functionalized multiwalled carbon nanotubes (f-MWCNTs) can serve as the pseudostationary phase (PSP) for the capillary EKC separation of non-steroidal anti-inflammatory drugs (NSAIDs). To increase their hydrophilicity, we treated MWCNTs, with a sonochemical process in a concentrated nitric/sulfuric acid mixture. The oxidized MWCNTs were then characterized by FT-IR, transmission electron microscopy, and X-ray photoelectron spectroscopy. We evaluated the potential of the PSP and the effects of buffer composition, pH, addition of organic modifier, and injection temperature on the NSAID separation. The PSP created a network structure of pi-pi interactions, hydrophobic forces, hydrogen bonding, and electrostatic interactions to separate NSAIDs, providing a different separation mode from SDS micelles. We achieved complete separation of six NSAIDs using a mixture of a borate buffer (75 mM, pH 10) with methanol (5%, v/v) containing 0.02 mg/mL f-MWCNTs, an applied voltage of +12 kV and detection at 214 nm. Better precision was obtained with a low injection temperature. The method was also satisfactorily applied to the analysis of NSAIDs spiked into a urine sample.

Enantiomer Resolution of Nonsteroidal Anti-Inflammatory Drugs on Chiral Stationary Phases Derived from Polysaccharide Derivatives

Abstract The liquid chromatographic enantiomerPDF separation of nonsteroidal anti-inflammatory drugs (NSAIDs) was performed on covalently immobilized chiral stationary phases (CSPs) (Chiralpak IA, Chiralpak IB, and Chiralpak IC) and coated-type CSPs (Chiralpak AD and Chiralcel OD) derived from polysaccharide derivatives. The chromatographic conditions were as follows: the flow rate was 1.0 ml min−1, the detection wavelength was 254 nm, and the standard mobile phase was 2-propanol/hexane/trifluoroacetic acid on all CSPs. A mobile phase of 2-propanol/hexane/trifluoroacetic acid = 10:90:0.1 (v/v) and 2:98:0.1 (v/v) were used on Chiralpak AD and Chiralcel OD of coated-type CSPs, respectively. Several solvents (dichloromethane, tetrahydrofuran, and ethyl acetate) in the mobile phase were used on covalently immobilized CSPs (Chiralpak IA, Chiralpak IB, and Chiralpak IC) and, therefore, solvent versatility of the covalently immobilized CSPs for enantiomer separation of NSAIDs was shown. Also, chromatographic comparisons for enantiomer resolution of these analytes were made on amylose tris (3,5-dimethylphenylcarbamate) derived CSPs (Chiralpak IA and Chiralpak AD) and cellulose tris (3,5-dimethylphenylcarbamate) derived CSPs (Chiralpak IB and Chiralcel OD), respectively. The results indicated that Chiralpak IA and Chiralpak IB showed generally lower enantiomer separation than Chiralpak AD and Chiralcel OD, respectively.

Capillary electrochromatographic separation of non-steroidal anti-inflammatory drugs with a histidine bonded phase.

An open tubular wall-coated capillary column containing histidine functional groups was prepared and employed for the capillary electrochromatographic separation of non-steroidal anti-inflammatory drugs. The anion exchange along with the hydrogen bonding and hydrophobic properties of the surface coating allowed the separation of analytes with very similar ionic mobility. Selectivity and resolution were studied by changing the pH over the range from 3.5 to 5.0 and the concentration of the buffer from 10 to 25 mM, as well as variation of the organic modifier, such as methanol, ethanol and 1-propanol over the range 7.5 to 20%. The optimum experimental conditions for the separation of a drug mixture, which consisted of indoprofen, ketoprofen, suprofen, naproxen, flurbiprofen, fenoprofen and ibuprofen were using a mixture of acetate buffer (20 mM, pH 5.0)-ethanol (1:5, v/v) as background electrolyte and an applied voltage of -20 kV with UV detection at 220 nm. The separation of these drugs could be achieved with an average plate number of 1.0 x 10(5) m(-1).

Capillary electrochromatography and capillary electrochromatography–electrospray mass spectrometry for the separation of non-steroidal anti-inflammatory drugs

In this study capillary electrochromatography (CEC) was utilized for the separation of ten non-steroidal anti-inflammatory drugs (NSAIDs). Experiments were carried out in a commercially available CE instrument using a packed capillary with RP-18 silica particles where the stationary phase completely filled the capillary. The mobile phase consisted of a mixture of ammonium formate buffer pH 2.5 and acetonitrile. Selectivity and resolution were studied changing the pH and the concentration of the buffer, the acetonitrile content mobile phase and the capillary temperature. The optimum experimental conditions for CEC separation of the studied drug mixture were found using 50 m M ammonium formate pH 2.5–acetonitrile (40:60) at 25°C. The CEC capillary was coupled to an electrospray mass spectrometer for the characterization of the NSAIDs. A mobile phase composed by the same buffer but with a higher concentration of acetonitrile (90%) was used in order to speed up the separation of analytes.

Study of method validation criteria in a capillary electrophoresis method for the separation of non-steroidal anti-inflammatory drugs

The separation of three non-steroidal anti-inflammatory drugs (NSAIDs) by a capillary electrophoresis (CE) method was examined and validated. The method was first optimised using experimental designs (half-fraction factorial designs for five factors). The finally selected conditions consisted of a borate buffer with ionic strength 0.09 and pH 9.0, an applied voltage of 20 kV and an injection time of 10 s. The validation of the method showed good results for the selectivity, linearity, system repeatability and bias. The results obtained from peak areas, corrected peak areas and peak heights were compared. The calibration lines from peak areas and corrected peak areas were linear while those from peak heights curved. In some concentration ranges the data were heteroscedastic. The ordinary least squares (OLS) and weighted least squares (WLS) regressions were used and compared in a low-concentration range of the drug solution. Half-fraction factorial designs were also applied to test the robustness of the method. The validation of the method approves the assay for the quantitative determination of the examined substances, occurring alone or in mixtures.

Separation of non-steroidal anti-inflammatory drugs by capillary electrophoresis using non-aqueous electrolyte.

Separation of non-steroidal anti-inflammatory drugs by capillary electrophoresis using non-aqueous electrolyte.

Separation of non-steroidal anti-inflammatory drugs by capillary electrophoresis using non-aqueous electrolyte

Separation of non-steroidal anti-inflammatory drugs by capillary electrophoresis using non-aqueous electrolyte

Separation of nonsteroidal anti-inflammatory drugs by capillary electrophoresis using nonaqueous electrolytes

The aim of the present work was to investigate the separation of nonsteroidal anti-inflammatory drugs (NSAIDs: niflumic acid, flufenamic acid, piroxicam, alclofenac, tiaprofenic acid, flurbiprofen, suprofen, ketoprofen, naproxen, indomethacin, carprofen, indoprofen, sulindac) in capillary electrophoresis (CE) using completely nonaqueous systems. The influence of different parameters such as nature and proportion of organic solvent (methanol, acetonitrile, 2-propanol), apparent pH (ranging from 7 to 9) and temperature (ranging from 25 to 40 degrees C) on selectivity and migration times were studied systematically in an uncoated fused-silica capillary. A nonaqueous electrolyte made of 50 mM ammonium acetate - 13.75 mM ammonia in methanol proved to resolve 11 NSAIDs at 25 degrees C and 13 NSAIDs at 36 degrees C, both within 13 min and without a modifier besides the methanol itself. The same buffer containing 30% acetonitrile provides a satisfactory separation for 13 NSAIDs within 14 min at 25 degrees C.