1-octanesulfonic Acid Research Articles

Unrefined and Milled Ilmenite as a Cost-Effective Photocatalyst for UV-Assisted Destruction and Mineralization of PFAS.

Per- and polyfluoroalkyl substances (PFAS) are fluorinated and refractory pollutants that are ubiquitous in industrial wastewater. Photocatalytic destruction of such pollutants with catalysts such as TiO2 and ZnO is an attractive avenue for removal of PFAS, but refined forms of such photocatalysts are expensive. This study, for the first time, utilized milled unrefined raw mineral ilmenite, coupled to UV-C irradiation to achieve mineralization of the two model PFAS compounds perfluorooctanoic acid (PFOA) and perfluoro octane sulfonic acid (PFOS). Results obtained using a bench-scale photocatalytic reactor system demonstrated rapid removal kinetics of PFAS compounds (>90% removal in less than 10 h) in environmentally-relevant concentrations (200-1000 ppb). Raw ilmenite was reused over three consecutive degradation cycles of PFAS, retaining >80% removal efficiency. Analysis of degradation products indicated defluorination and the presence of shorter-chain PFAS intermediates in the initial samples. End samples indicated the disappearance of short-chain PFAS intermediates and further accumulation of fluoride ions, suggesting that original PFAS compounds underwent mineralization due to an oxygen-radical-based photocatalytic destruction mechanism induced by TiO2 present in ilmenite and UV irradiation. The outcome of this study implies that raw ilmenite coupled to UV-C is suitable for cost-effective reactor operation and efficient photocatalytic destruction of PFAS compounds.

Development and Validation of Stability-Indicating Impurity Profiling Method for Azelastine Hydrochloride and Fluticasone Propionate in Nasal Spray Product Using HPLC with a UV/PDA Detector.

Azelastine HCl (AZ) and fluticasone propionate (FL) nasal spray drug product is commonly used in the treatment of allergic rhinitis worldwide. To date, the impurity profiling of this product has not been reported. The present study aimed to develop and validate a novel RP-HPLC stability-indicating analytical method for the estimation of impurities from AZ and FL nasal spray drug product. A mixture of octane sulfonic acid sodium salt and trifluroacetic acid is used as a mobile phase A. Acetonitrile is used as a mobile phase B. Good separation was achieved on Baker bond phenyl hexyl, 250 × 4.6, 5 µm column at 1 mL/min flow rate in gradient elution mode. The chromatograms were monitored at 239 nm. The LOD and LOQ were found to be 0.006 and 0.019 µg/mL for AZ and 0.010 and 0.030 µg/mL for FL, respectively. The correlation coefficient for all the known impurities and principal analytes was 0.999 from LOQ level to 150% of standard concentration. The recovery for all the known impurities was found to be between 90 and 110%. In the stress study, 15% degradation was observed in basic conditions and 8.7% in acidic conditions. No significant degradation was observed in thermal and oxidative conditions. An impurity profiling method for AZ and FL combination nasal spray product was successfully developed, validated, and demonstrated to be accurate, precise, specific, robust, and stability-indicating. The method can be routinely used for impurity testing of commercial batches in QC laboratories in the pharmaceutical industry. No impurity study has been reported for this combination product until now.

Validated HPLC-UV Method for Simultaneous Estimation of Paclitaxel and Doxorubicin Employing Ion Pair Chromatography: Application in Formulation Development and Pharmacokinetic Studies.

Though paclitaxel (PTX) and doxorubicin (DOX) are amongst the most widely used and investigated drug pair for combination chemotherapy but surprisingly, not a single validated HPLC-UV method is available to analyze PTX and DOX simultaneously. So, herein a HPLC-UV method is developed and validated for the same, filling an indispensable gap in the literature. As these two moieties have characteristically different polarities, resolving them under the common chromatographic conditions is a challenging task. Herein, the principle of ion pair chromatography is utilized to resolve these two moieties on a C18 column employing an isocratic mobile phase comprised of acetonitrile and octane sulfonic acid buffer (67 : 37) and detected simultaneously at 231 nm using a UV detector only. The retention time is 4.4 and 7.2 min for PTX and DOX, respectively, with a total analysis time of less than 10 minutes, suitable for the formulation development and research, while LOQ is less than 0.066 μg/ml for both the drugs, suitable for the therapeutic drug monitoring at preclinical and clinical research setup. To substantiate the applicability of the developed method, a nanoformulation coloaded with PTX and DOX was designed and analyzed using the developed protocol. The method is also applied successfully to study the plasma kinetic profile of both the moieties simultaneously in Balb/c mice. Further, the method is validated as per the ICH guidelines fulfilling the unmet need of a validated analytical tool to simultaneously estimate PTX and DOX. Moreover, the results suggest that the principal of common ion chromatography demonstrated here can also be applied further for the simultaneous chromatographic separation of other polar and nonpolar moieties too. Consequently, the reported method surely will advance the toolset required for the precision-based combination chemotherapy.

Impurity profiling method development and validation of metformin hydrochloride and teneligliptin hydrobromide hydrate in their combination tablet dosage form by using RP-HPLC with UV/PDA detector

BackgroundAn accurate, precise and robust analytical method was developed for the impurity profiling in the metformin hydrochloride and teneligliptin hydrobromide hydrate tablet. The gradient was optimized for better separation of impurities by using BDS Hypersil C18 250 × 4.6 mm, 5µ column operated at 35 °C. The octane sulfonic acid and phosphate buffer with triethylamine at pH 3.0 were used as mobile phase A, and acetonitrile was used as mobile phase B. The mobile phase was pumped at 1.0 mL/min. The gradient was optimized for better resolution, and the chromatogram was monitored at 210 nm.ResultsThe % recovery of teneligliptin and metformin HCL observed was above 90% from LOQ level to 150%. The correlation coefficient r2 was 0.999 for metformin HCl, teneligliptin, melamine, cyanocobalamin, teneligliptin impurity A and 0.998 for teneligliptin impurity B. The method was found unaffected by change in method variance during the robustness study. During the stress study with acid, base, peroxide and temperature, maximum degradation was observed with peroxide indicating the sensitivity of the molecule toward oxidative stress.ConclusionsThe developed method is precise, accurate, robust and linear and hence can be routinely used for the related substance analysis of metformin hydrochloride and teneligliptin hydrobromide hydrate tablet in the quality control laboratory at manufacturing site during the commercial manufacturing.

Highly accurate and New approach for quantiϐication of Gramicidin in medication by RP-HPLC

A significant Reverse Phase-High performance Liquid Chromatography technique was developed for a more accurate, unique and quick economical method was developed for the analysis of Gramicidin in medication dosage forms. The separation of this drug Gramicidin was done by using the X-Bridge phenyl column as a stationary phase, and a mixture of acetonitrile + buffer in 50:50 v/v ratio was used as a movable phase. The buffer used in this method was Octane sulphonic acid of pH-2.5 adjusted with OPA. The maximum absorbance of eluents was observed at 235 nm. A specific flow rate (1 ml/minute) was maintained throughout the runtime of 8 min. The selected drug is eluted at 2.49 minutes. The selected drug obeys Beer Lambert's law in the concentration range of 0.5-7.5 µg/ml of Gramicidin. The percentage of recovery was found to be within the acceptable limit. The selected approach was corroborated with ICH standard ground rules, and the results of parameters like method precision, accuracy, ruggedness, robustness, and degradation studies were found to be within the allowable limit. Thus, the present method was successfully applied for the simultaneous analysis of Gramicidin in routine industrial work.

1, 4-Diazabicyclo[2.2.2]octane-sulfonic acid immobilized on magnetic Fe3O4@SiO2 nanoparticles: a novel and recyclable catalyst for the one-pot synthesis of 4-aryl-NH-1, 2, 3-triazoles

In this study, the surface of silica-coated magnetic nanoparticles (Fe3O4@SiO2) were successfully functionalized by an organic ligand of 1, 4-Diazabicyclo[2.2.2]octane (DABCO)-sulfonic acid and used as a highly efficient catalyst for the synthesis of 4-aryl-NH-1, 2, 3-triazoles from the benzyl alcohol derivatives, nitromethane and sodium azide in ethanol. Furthermore, this catalyst could be recovered and reused five times without noticeable loss of activity. Fe3O4@SiO2@TCT-DABCO-SO3H nanoparticles were successfully synthesized and used as a novel, recyclable, efficient and heterogeneous catalyst for the synthesis of 4-aryl-NH-1, 2, 3-triazoles.

SEPARATION AND ASSAY OF FOUR ANTIHISTAMINE DRUGS DIPHENHYDRAMINE, CHLORPHENIRAMINE, CYPROHEPTADINE AND FEXOFENADINE IN PHARMACEUTICAL FORMS BY A SINGLE HPLC METHOD

Objective: The objective of this study was to develop and validate a single HPLC method, in order to separate and assay four antihistamine drugs diphenhydramine, chlorpheniramine, cyproheptadine and fexofenadine in pharmaceutical forms. This method was a practical additional choice in quality control laboratories.Methods: The chromatographic conditions comprised of a classical C18-type stationary phase (150 × 4.6 mm, 5μ), with a mobile phase consisting of, 2.5g of sodium octane sulfonic acid in a mixture of 500 ml of deionized water and 500 ml of acetonitrile, and apparent pH of 2.0 was adjusted with phosphoric acid. The flow rate was 1 ml/min; the detection wavelengths were at 220 nm, 230 nm, 265 nm and 254 nm for diphenhydramine, chlorpheniramine, cyproheptadine and fexofenadine respectively. The temperature was ambient temperature.Results: The method was validated for linearity with correlation coefficients very close to one, the accuracy with mean recovery values between 95.0-105.0%, precision with relative standard deviations of the calculated concentrations less than 5.0% and specificity in the presence of degradation products. Then it was used successfully to separate a mixture of them and to assay these drugs in pharmaceutical forms purchased from Syria.Conclusion: The results presented in this paper showed that the developed method was simple and applicable, for the separation and determination of the four drugs in their pharmaceutical forms.

Determination of rare earth elements at trace levels in uranium process stream samples by ion-interaction chromatography

Determination of rare-earth elements like Ce, Sm, Eu, Gd, Dy, Er at trace levels in uranium process stream samples has been investigated by ion-interaction chromatography using C18 column, cation exchange based pre-concentration column (PCC). A mixture of α-hydroxy-iso-butyric acid and octane sulfonic acid is used as eluent after separation of uranium by solvent extraction. The trapping of analytes by PCC is found to be maximum in the pH range of 2.9–3.7 of sample solution. The spiking standard recovery for each analyte was found to be more than 90% and the method can be employed regularly.

Friedel–Crafts alkylation of 4-hydroxycoumarin over silica-bonded 1,4-diaza-bicyclo[2.2.2] octane-sulfonic acid chloride as nanostructured heterogeneous catalyst

A novel nanostructured heterogeneous catalyst, namely silica-bonded 1,4-diaza-bicyclo[2.2.2]octane-sulfonic acid chloride (SBDBSAC), has been synthesized and fully characterized by several techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential thermal gravimetric (DTG), scanning electron microscope (SEM), and energy dispersive X-ray analysis (EDX). Afterward, the nanostructured catalyst was utilized as an efficient catalyst for the synthesis of bis-coumarin derivatives by the condensation reaction of arylaldehydes with 4-hydroxycoumarin at 70 °C under solvent-free conditions.

Novel Validated RP-HPLC Method for Bendamustine Hydrochloride Based on Ion-pair Chromatography: Application in Determining Infusion Stability and Pharmacokinetics.

Ion pair chromatography was used for quantifying bendamustine hydrochloride (BH) in its marketed vial. The permissive objective was to investigate time duration for which highly susceptible drug content of the marketed vial remained stable after reconstitution. However, the method could also be used to measure extremely low levels of drug in rat plasma and a pharmacokinetic study was accordingly conducted to further showcase method's applicability. Optimized separation was achieved on C-18 Purospher®STAR (250 mm×4.6 mm, 5 μm particle size) column. Mobile phase flowing at 1.5 mL/min consisted of 5 mM sodium salt of octane sulfonic acid dissolved in methanol, water and glacial acetic acid (55:45:0.075) maintained at pH 6. Detection was carried out at 233 nm with BH eluting after 7.8 min. Validation parameters were determined as per ICH guidelines. Limit of detection and limit of quantification were found to be 0.1 µg/mL and 0.33 µg/mL, respectively. The recoveries were 98-102% in bulk and 85-91% in plasma. The developed method was specific for BH, and utilized for assessing its short-term stability in physiologic solvents and forced degradation products in acid, base, oxidative, light and temperature induced stress environments.

Silica-bonded 1,4-diaza-bicyclo[2.2.2]octane-sulfonic acid chloride catalyzed synthesis of spiropyran derivatives

In this research, a novel nanostructured heterogeneous catalyst, namely silica-bonded 1,4-diaza-bicyclo[2.2.2]octane-sulfonic acid chloride (SBDBSAC), as an acidic ionic liquid based on 1,4-diaza-bicyclo[2.2.2]octane ring bonded to silica has been prepared and fully characterized by several techniques such as fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential thermogravimetric (DTG), scanning electron microscope (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The nanostructured catalyst has been suxessfully used as reusable nanostructured catalyst for green, simple and efficient synthesis of spiropyrans by the one-pot tandem Knoevenagel-Michael-cyclization reaction of isatin derivatives or acenaphthenquinone with barbituric acid derivatives, and 1,3-dicarbonyl compounds under aqueous media.

Development and validation of HPLC method with fluorometric detection for quantification of bisnaphthalimidopropyldiaminooctane in animal tissues following administration in polymeric nanoparticles

A simple, sensitive and specific high-performance liquid chromatography method for the quantification of bisnaphthalimidopropyldiaminooctane (BNIPDaoct), a potent anti-Leishmania compound, incorporated into poly(d,l-lactide-co-glycolic acid) (PLGA) nanoparticles was developed and validated toward bioanalysis application. Biological tissue extracts were injected into a reversed-phase monolithic column coupled to a fluorimetric detector (λexc=234nm, λem=394nm), using isocratic elution with aqueous buffer (acetic acid/acetate 0.10M, pH 4.5, 0.010M octanesulfonic acid) and acetonitrile, 60:40 (v/v) at a flow rate of 1.5mLmin−1. The run time was 6min, with a BNIPDaoct retention time of 3.3min.Calibration curves were linear for BNIPDaoct concentrations ranging from 0.002 to 0.100μM. Matrix effects were observed and calibration curves were performed using the different organ (spleen, liver, kidney, heart and lung) extracts. The method was found to be specific, accurate (97.3–106.8% of nominal values) and precise for intra-day (RSD<1.9%) and inter-day assays (RSD<7.2%) in all matrices. Stability studies showed that BNIPDaoct was stable in all matrices after standing for 24h at room temperature (20°C) or in the autosampler, and after three freeze–thaw cycles. Mean recoveries of BNIPDaoct spiked in mice organs were >88.4%. The LOD and LOQ for biological matrices were ≤0.8 and ≤1.8nM, respectively, corresponding to values ≤4 and ≤9nmolg−1 in mice organs. The method developed was successfully applied to biodistribution assessment following intravenous administration of BNIPDaoct in solution or incorporated in PLGA nanoparticles.

Novel liquid chromatographic methods for the determination of varenicline tartrate

Two simple, sensitive, rapid, and stability-indicating liquid chromatographic (LC) methods have been developed for the determination of varenicline tartrate. They comprised the determination of varenicline (VRC) in the presence of its oxidative degradates and related impurity (N-formyl varenicline) (NFV). The first method was a LC with diode array detection (DAD) at 235nm using Ristek-Ultra® C18 column (100mm×2.1mm, 5µm). Isocratic elution of VRC was employed using a mobile phase consisting of buffer mixture (1.2% potassium dihydrogen phosphate and 0.08% octane sulphonic acid): acetonitrile (86:14, v/v), pH (5.0). In the second method; a fluorimetric detection technique was developed, based on precolumn derivatization of VRC using 7-chloro-4-nitrobenzo-2-oxa-1, 3-diazole (NBD-Cl). The fluorescence detector (FLD) was operated at 474nm for excitation and 539nm for emission. Isocratic elution was applied with a mobile phase consisting of methanol-distilled water (70:30, v/v). Separation was achieved using Symmetry® Waters C18 column (150mm×4.6mm, 5µm). Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 0.5–20.0µgmL−1 and 0.2–20.0µgmL−1 with the first and the second method, respectively. The optimized methods were validated and proved to be specific, simple, and accurate for the quality control of the drug in its pharmaceutical preparation.

Evaluation of Catecholamine Levels in Iraqi Female Parkinson's Patients by Using HPLC Technique

High performance liquid chromatography Reversed–phase (Rp-HPLC) was used to estimate noradrenaline (NA), adrenaline (AD) and dopamine (DA) in the female plasma blood samples of normal volunteer's and Parkinson's patients before and after treatment with levodopa drug. Optimal condition based on ion-pairing has been performed to measure NA, AD and DA on ODS-DB column using 50 mM phosphate buffer mixed with 0.5 mM of 1- octane sulphonic acid: acetonitrile (95:5) at pH = 4.5 and monitored by UV-Visible spectrophotometer at 280 nm.The chromatographic linearity appears to be linear in the range 0.5-10.0 ppm. The results show that the plasma concentration levels of NA, AD and DA in female normal volunteers were (236(64)), (265(84)) and (692(165)) ng/mL, respectively, whereas the plasma concentration levels of NA, AD and DA in female Parkinson's patients were (277(41)), (175(32)) and (127(42)) ng/mL before treatment with Levodopa drug using general dose of 100 mg/day. After treatment the plasma, the concentration levels become (277(37)), (214(45)) and 359(83)) ng/mL, respectively. Probably, this study has revealed that the non-enzymaticoxidation of NA in addition to DA, promotes a toxic effect by causing an inactivation of the vesicular H+-ATPase.

Microextraction by packed sorbent (MEPS) to analyze catecholamines in innovative biological samples

A new microextraction by packed sorbent (MEPS) procedure coupled to a high-performance liquid chromatographic method has been developed for quantitation of catecholamines (i.e. norepinephrine, epinephrine and dopamine) in innovative biological samples, namely dried plasma and urine spots. Analyses were carried out on a C18 reversed-phase column using a mobile phase composed of 2.5% methanol and 97.5% aqueous citrate buffer, containing octanesulfonic acid. Coulometric detection was used, setting the first analytical cell at −0.350V and the second analytical cell at +0.400V. Dried matrices were purified by means of a fast and feasible MEPS procedure, optimized on C18 sorbent and requiring only a small amount of biological sample. The availability of miniaturized procedures allowed satisfying specific requirements that ought to be considered during pre-treatment intended for catecholamine analysis. The extraction yield values were always higher than 85% and sensitivity was good, with a limit of quantitation of 100pgmL−1 for all the analytes. Satisfactory results were also obtained in terms of linearity, precision and accuracy. The method was successfully applied to dried plasma and urine spots derived from two socially diversified groups, namely psychiatric patients and poly-drug abusers, in comparison to healthy volunteers.

An Isocratic Toxic Chemical-Free Mobile Phase HPLC-PDA Analysis of Malachite Green and Leuco-Malachite Green

This paper describes a reserved-phase high-performance liquid chromatographic (HPLC) method for detecting malachite green (MG) and leuco-malachite green (LMG) using an isocratic toxic organic solvent/reagent-free mobile phase. Chromatographic separations were performed an Inertsil® WP300 C4 with 0.02 mol/L octane sulfonic acid–ethanol mobile phase and a photodiode-array detector. The total run time was &lt;5 min. The system suitability was well within the international acceptance criteria. A harmless method for simultaneously detecting MG and LMG was developed and may be further applied to the quantification in foods.

New Spectrophotometric Methods for the Quantitative Analysis of Fluorometholone in Ophthalmic Suspensions

Two simple, rapid and sensitive spectrophotometric methods were developed for the determination of Fluorometholone in pharmaceutical formulations in methanol (Method A) and Octane sulfonic acid buffer (pH 3.0) (Method B). Beer's law was obeyed over the concentration range 0.1-80 μg/mL in both methods. The linear regression equations were found to be y = 0.040x + 0.005 and y = 0.040x - 0.013 in Method A and B respectively. The % RSD was found to be 0.76 and 0.97 in Method A as well as 0.58 and 0.49 in Method B for intra-day and inter-day precision studies. The % RSD in accuracy studies was also found to be less than 2.0. The proposed methods are simple and suitable for the determination of Fluorometholone in pharmaceutical formulations. No interferences were observed from the excipients in the formulations. The methods were validated according to ICH guidelines.

Ion-Pair LC Method for Simultaneous Determination of Aliskiren Hemifumarate, Amlodipine Besylate and Hydrochlorothiazide in Pharmaceuticals

A rapid and precise LC method was developed for the simultaneous determination of aliskiren hemifumarate (ALS), amlodipine besylate (AML) and hydrochlorothiazide (HCZ) using acetonitrile:25 mM octane sulfonic acid sodium salt monohydrate in water (60:40 v/v) as the mobile phase. The flow rate was maintained at 1.2 mL min−1 on a stationary phase composed of Supelco, Discovery® HS (C18) column (25 cm × 4.6 mm, 5 μm). Isocratic elution was applied throughout the analysis. Detection was carried out at λ max (232 nm) at ambient temperature. The method was validated according to ICH guidelines. Linearity, accuracy and precision were satisfactory over the concentration ranges of 32–320, 2–44 and 4–64 μg mL−1 for ALS, AML and HCZ, respectively. LOD and LOQ were estimated and found to be 0.855 and 2.951 μg mL−1, respectively, for ALS, 0.061 and 0.202 μg mL−1, respectively, for AML as well as 0.052 and 0.174 μg mL−1, respectively, for HCZ. The method was successfully applied for the determination of the three drugs in their co-formulated tablets. The results were compared statistically with reference methods and no significant difference was found. The developed method is specific and accurate for the quality control and routine analysis of the cited drugs in pharmaceutical preparations.

An isocratic solvent-free mobile phase HPLC-PDA analysis of clenbuterol and ractopamine

Abstract This paper describes a reserved-phase HPLC method for detecting clenbuterol (CB) and ractopamine (RP) using an isocratic solvent-free mobile phase. The separations were performed a Kaseisorb ® LC C1-300-5 (100 × 4.6 mm, 5 μm) with 0.05 mol/L octane sulfonic acid mobile phase and a photodiode array detector. The total run time was

Improved reversed phase liquid chromatographic method with pulsed electrochemical detection for tobramycin in bulk and pharmaceutical formulation

Tobramycin is one of the aminoglycoside antibiotics that lack a UV absorbing chromophore. However, the application of pulsed electrochemical detection (PED) has been used successfully for the analysis of this and similar antibiotics. This work describes an improved liquid chromatographic (LC) method combined with PED, which is able to separate much more impurities than before. Using a Discovery C-18 RP column (250mm×4.6mm i.d., 5μm), isocratic elution was carried out with a mobile phase, containing sodium sulfate (35g/L), sodium octanesulphonic acid (1g/L), tetrahydrofuran (14mL/L) and 0.2M phosphate buffer pH 3.0 (50mL/L). Using these experimental conditions, the limit of quantification (LOQ, S/N=10) was 5ng. The linearity was examined in the range LOQ-60μg/mL and the coefficient of determination was 0.998. The method also proved to be repeatable and the recovery was close to 100%. The influence of the different chromatographic parameters on the separation was investigated by means of an experimental design. The proposed method is useful in quality control of tobramycin drug substances and drug products.