Hexanesulfonic Acid Research Articles

A stability-indicating HPLC assay of ten different vitamins in a food supplement: Appraisal of the method's greenness, whiteness, and blueness

Due to their susceptibility to degradation, vitamin levels in food formulations may differ from those found in the finished product. Vitamin levels can be impacted by processing and storage. In this work, the ingredients of Strong B50 ® film-coated tablets were estimated simultaneously using simple efficient stability indicating HPLC method. Strong B50 ® film-coated tablets contain thiamine (VB1), riboflavin (VB2), calcium pantothenate (VB5), pyridoxine (VB6), vitamin C (VC), folic acid (FA), biotin (BT), inositol (IS), niacin (NC), para-aminobenzoic acid (PB), cyanocobalamine (B12), choline bitartarate, and iron gluconate. Hypersil BDS C18 column was used for achieving reasonable separation. Mobile phases (A) and (B) were utilized, the mobile phase (A) consisted of 0.015 M Hexane sulfonic acid sodium salt + 0.1 % Triethylamine and orthophosphoric acid was used to adjust the pH to (2.9) while (B) system consisted of acetonitrile. Validation of the method was assessed using International Conference of Harmonization (ICH) parameters, where linearity, accuracy, selectivity, and robustness of the method were investigated. Correlations were above 0.99, accuracy results ranged from 97.6 to 102.8 % and limits for detection and quantitation (LOD and LOQ) values were determined for each vitamin in μg/mL except for FA and BT in ng/mL. LOD values were between 0.006 and 15.08 μg/mL while LOQ values ranged from 0.031 to 49.77 μg/mL. Stability studies were conducted under stressed conditions and degradation percentages were computed. Where, VB5, VB6, FA and PB, VC, and NC were the most degradable vitamins. Whiteness evaluation using the modern RGB 12 algorithm compared our method and the old reported one by Sasaki et al., 2020. The comparison favored our newly developed method in terms of analytical performance, practical applicability and greenness. Besides, AGREE and GAPI soft wares were used to assess the greenness of the method. It was clear that the results of colored pictograms confirm low hazardous impact and that the new method is greener with AGREE score of 0.66. Furthermore, the functionality and applicability of the novel HPLC approach were concluded via the Blue Applicability Grade Index (BAGI) tool with a final score of 82.5.

Design of Experiment Enhanced Development and Validation of RP-HPLC Method for Analysis of Ascorbic Acid and Rutin

This work intends to develop a QbD-based RP-HPLC method and validate rutin (RU) and ascorbic acid (ASC) in combined tablet dosage form. The method is optimized by the central composite design. The independent variables chosen are mobile phase ratio and pH. The dependent variables are retention time for RU (R1), retention time for ascorbic acid ASC (R2), and resolution (R3). Analysis of variance revealed that the method parameters were significant (p <5). Waters Alliance-e2695 [C18 (150x 4.6 mm, 3.5)] was used to separate rutin and ascorbic acid using a mobile phase Acetonitrile: Hexane Sulphonic Acid (pH-2.5/OPA) in a 70:30 ratio, the selected wavelength was 215 nm. Method validation and degradation studies were performed ICH guidelines are followed. The approach was determined to be easy, suitable, accurate, precise, and robust for quantitative analysis of ascorbic acid and rutin.

Development of an eco-friendly HPLC method for the stability indicating assay of binary mixture of ibuprofen and phenylephrine

The development and validation of the stability indicating HPLC technique has contributed to the understanding of the stability profile of ibuprofen (IBU) and phenylephrine (PHE). Stability profile was achieved for PHE; the drug was found to be liable to be influenced by stress oxidative conditions; two oxidative degradants (Deg1 & Deg2) were formed and their structures were confirmed using IR and mass spectrometry. The drugs and degradation products were successfully separated using a gradient elution method on YMC-C8 column with 0.1% hexanesulfonic acid and acetonitrile as a mobile phase at pH 6.6. The flow rate was 1.0 mL/min, and a diode array detector operating at 220 nm was used for UV detection. The retention times of degradants Deg1, Deg2, ibuprofen (IBU), and phenylephrine hydrochloride (PHE) were 2.0, 2.2, 3.2 and 7.0 min, respectively. The proposed method was validated with respect to linearity, accuracy, precision, specificity, and robustness using ICH guidelines. The linearities of ibuprofen and phenylephrine hydrochloride were in the range of 10–100 μg/mL and 0.3–10 μg/mL, respectively. The % recoveries of the two drugs were found to be 100.75 ± 1.44%, 99.67% ± 1.67, and the LOD was found to be 2.75/mL and 0.09/mL for IBU, and PHE, respectively. The method was successfully applied to the estimation of ibuprofen and phenylephrine hydrochloride combination in pharmaceutical dosage form. The proposed technique was validated using ICH guidelines and its greenness was assessed according to Analytical Eco Scale metric (AES). Molecular docking was used to assess the two drugs and PHE oxidative degradants interaction with the stationary phase and to confirm the outcomes of the proposed method with regard to the order of elution of the two drugs and PHE degradation products. Eco-friendly and environmental safety were assessed through the application of one of the most applicable greenness assessment tool; Analytical Eco Scale metric (AES).

Development of a Simple Accurate Method, Validation and It’s Degradation Studies of Nirmatrelvir, Ritonavir in Bulk and Marketed Formulation by RP-HPLC

An easy, accurate, and precise method used for simultaneous quantification of nirmatrelvir, ritonavir in bulk and marketed formulation by reverse phase high performance liquid chromatography (RP-HPLC) using a standard column Inertsil ODS (150 x 4.6 mm, 5 μm ) at a rate of flow 1-mL/min, acetonitrile and buffer containing hexane sulphonic acid, 50:50 v/v as a mobile phase was introduced through the HPLC column, detected at a wavelength 258 nm. Nirmatrelvir and ritonavir retention times were 2.481 and, 3.873 minutes, respectively. %Recovery rates for nirmatrelvir and ritonavir were 100 and 100.3%, respectively. LoD and LoQ values for nirmatrelvir and ritonavir were 1.5, 1 and 4.5, 3 g/mL, respectively. Nirmatrelvir regression equation is y = 32885.25x + 4223.04 while ritonavir is y = 39086.65x + 1680.21. Stability indicating studies done by acid, alkali, peroxide, Reduction, thermal, neutral and ultra violet light. The newly created reverse phase HPLC method, for bulk and marketed formulation, was rapid, stability indicating and accurate

Validated RP-UPLC-PDA Method for simultaneous Estimation of Artemether and Lumefantrine in API and Tablet dosage form

A specific, precise, accurate and robust isocratic RP-UPLC-PDA assay method was developed and validated for determination of Artemether and Lumefantrine in API and tablet dosage form. Isocratic separation was achieved on an Acquity UPLC BEH C18 column (50mm, 2.1mm, and 1.7µm) using mobile phase of Acetonitrile: 20mM Hexane sulfonic acid sodium salt adjust pH 2.5±0.05 with Ortho phosphoric acid (70:30% V/V) at a flow rate of 0.3ml/min, Temperature 40℃. The injection volume was 5µl and the detection was carried out at 218nm by using photo-diode array detector. Retention time of Artemether and Lumefantrine were found to be 0.908 min and 1.916min. The calibration plots were over the concentration range of 80-240μg/ml and 480-1440µg/ml for Artemether and Lumefantrine with correlation coefficient 0.999 and 0.999 respectively. The accuracywasobtained between 98.8% - 100.56% and 98.15% - 101.51% for Artemether and Lumefantrine respectively. The short retention time allows the analysis of a large number of samples in a short period of time andtherefore, will be cost-effective for routine analysis in the pharmaceutical industry.

Quantification of all B vitamins in a single run using ion-pair modified liquid chromatography with UV detection

A rapid and simple approach based on ion-pair liquid chromatography for the estimation of all B vitamins in a single run of 35 min using UV detector is developed. The estimation is based on the separation of all B vitamins on the C18 column using gradient elution comprising mobile phase A (65% methanol) and B (sodium dihydrogen phosphate, pH 3.05 containing 5 mM hexane sulphonic acid as an ion-pair reagent). Vitamins B1, B2, B3, B6, B9, and B12 were detected at 255 nm, while vitamins B5 and B7 were best detected at 200 and 210 nm, respectively. The standardized protocol was validated in buffer and milk permeate. The correlation coefficient for all B vitamins determined using a linear regression equation in the range of 1–30 µg mL−1 was > 0.99. The relative standard deviation for intra-day and inter-day repeatability of vitamins (10 µg mL−1) was less than 6%, and recoveries were in the 75–120% range. The applicability of the developed method has also been demonstrated for the quantification of B vitamins (B2, B3, B5, B6) in fortified commercial energy drinks.

Related Substances Method Development and Validation of Axitinib, Zanubrutinib and Upadacitinib Using RP-HPLC and its Degradation Products were Characterized by Using LC-MS/MS

Background: Axitinib was used to treat carcinoma of renal cells and Upadacitinib was used to treat rheumatoid arthritis and Zanubrutinib used as an anti cancer medication for mantle cell lymphoma. In the current application, Zanubrutinib, Upadacitinib and Axitinib and their associated substances will be developed and validated. Materials and Methods: The optimised method includes the Zanubrutinib, Upadacitinib and Axitinib gradient elution and associated flow rates with dimensions of 1 mL/min and phenyl column X-bridge (150 x 4.6 mm, 3.5 μ). A mobile phase was employed with 1.2 g of Hexane sulphonic acid of pH-2.5 adjusted with ortho-phosphoric acid (buffer) and acetonitrile. Zanubrutinib, Upadacitinib and Axitinib were separated from their associated substances for a total run time of 60 min. The approach developed has been validated in accordance with the ICH guidelines. Results: The test concentration LOD and LOQ were established for both drugs and for their impurities. The diagrams that were drawn were straightforward with an R2 regression coefficient > 0.999. As part of the method validation, recovery, specificity, linearity, accuracy, robustness was determined and the results were found to be within an acceptable range. Conclusion: HPLC was used to validate the method in terms of accuracy, linearity, method precision, accuracy, limit of detection, limit of quantification, robustness, and degradation, and LC-MS/MS was used to characterise the degradation products. The system was validated in all of these aspects.

Development of a Validated Stability Indicating Method for Quantification of Amoxicillin, Clarithromycin and Lansoprazole in Bulk and Pharmaceutical Dosage form by RP-HPLC

Objective: The main objective of the present work is to develop an efficient, unique, reliable Reverse Phase High Performance Liquid Chromatography (RP-HPLC) method for the simultaneous quantification of Amoxicillin (AMX), Clarithromycin (CTM) and Lansoprazole (LPZ) in bulk and pharmaceutical formulations. 
 Methods: The chromatographic separation was achieved by using Kinetex column C18 (100 x 4.6 mm, 2.6 µm) with Buffer (2.5 g of hexane sulphonic acid and 1ml of Triethylamine which are added to 1000 ml of HPLC water and adjusted its pH at 5.0 with Ortho phosphoric acid) and acetonitrile in the ratio of 70: 30 (%v/v) as a mobile phase at flow rate of 1.0 ml/min. The column effluents were monitored by a photodiode array detector at wavelength predetermined at 240 nm.
 Results: The method produced reliable results at optimized chromatographic conditions. The method was linear at concentration range of 15-225 µg/ml of AMX, 15-225 µg/ml of CTM and 0.9-13.5 µg/ml of LPZ with regression coefficients of 0.9999, 0.9999, and 0.9999 respectively. The retention times of AMX, CTM, LPZ were obtained as 1.513, 3.124, 3.770 min respectively. Results obtained for system suitability, precision, LOD and LOQ were in acceptable range and were validated according to the guidelines of the International Council for Harmonization (ICH).
 Conclusion: The proposed method was validated in accordance with ICH and all the obtained results were found satisfactory and were successfully applicable to the analysis of the bulk and the pharmaceutical formulations.

A comparative study of two analytical techniques for the simultaneous determination of amprolium HCl and ethopabate from combined dosage form and in presence of their alkaline degradation.

Chemometric and separation-based techniques (HPLC) are the most applicable and versatile analytical techniques for the analysis of multicomponent mixtures, in the present contribution, a comparison was highlighted between the two analytical techniques of utmost importance as stability indicating assays: UV-spectrophotometry and HPLC-UV focusing on the greenness of each for the simultaneous determination of amprolium HCl (AMP) and ethopabate (ETHOP) in the presence of their alkaline degradation products. The first method was chemometric methods applied were PLS-1, GA-PLS and GA-ANN. To compare the prediction ability of the models, a 4-factor 5-level experimental design was used to establish a calibration set of 25 mixtures containing different ratios of the drugs and their degradation products. The validity of the proposed methods was assessed using an independent validation set of 5 mixtures. The comparison between the different models showed the superiority of ANN model in solving the highly overlapped spectra of the quaternary mixture, yet using inexpensive and easy to handle instruments like the UV-VIS spectrophotometer. The ANN method was used for the quantitative analysis of the drugs in pharmaceutical dosage form via handling the UV spectral data. The second method was based on liquid chromatographic HPLC determination of AMP and ETHOP using C18 column (250×4.6mm2)-PRONTOSIL 5μm, a mobile phase consisting of methanol: Hexane sulphonic acid sodium salt at (pH=3.4±0.2) adjusted by orthophosphoric acid (55: 45v/v). Quantitation was achieved with UV detection at 270nm at temperature 24°C. Linearity, accuracy and precision were found to be acceptable over the concentration range of 10.0-70.0 and 1.0-25.0μg·mL-1 for AMP and ETHOP, respectively. The proposed methods could be successfully applied for the routine analysis of the studied drugs either in their pure bulk powders or in their pharmaceutical preparations without any preliminary separation step. The results obtained were statistically compared with those obtained by applying the reported method.

Chromatographic Methods for the Determination of Aminexil, Pyridoxine, and Niacinamide in a Novel Cosmetic Hair Preparation.

Aminexil, a new compound patented by L'Oreal, has a stimulating effect on human keratin fibers. Pyridoxine HCl and niacinamide are added to boost the hair tonic effect of aminexil. Two novel chromatographic methods were developed for the determination of aminexil (AX), niacinamide (NA) and pyridoxine HCl (PD) in the novel hair tonic preparation. The developed methods were high-performance liquid chromatography (HPLC) and thin layer chromatography (TLC) with densitometric determination. Different experimental parameters were investigated and optimized to achieve complete baseline separation and well resolved peaks. The RP-HPLC separation was achieved using a Thermoscientific BDS hypersil C18 (250 × 4.6 mm, 5 µm) column using 0.005 M hexane sulfonic acid: methanol (80: 20, v/v) as a mobile phase. For the TLC method, the three analytes were partitioned between propanol: toluene: ammonia solution (40:60:2, v/v/v) and fluorescent silica plates. The two methods were validated in compliance with International Conference on Harmonization (ICH) guidelines. The obtained data were statistically analyzed to confirm the existing results. The developed methods were successfully applied for determination of the studied drugs in pure forms and in the cosmetic preparation. For the HPLC method, the RSDs of AX, NA and PD were 0.70, 0.88 and 1.17 respectively. For the TLC method, the RSDs of AX, NA and PD were 1.06, 1.37 and 0.73 respectively. The proposed chromatographic methods showed high sensitivity and selectivity for the three compounds under analysis in the laboratory prepared mixture and in the hair tonic preparation. Aminexil, Pyridoxine, Niacinamide, HPLC. The present work offers two reproducible, accurate, validated, time and cost saving alternatives for the quantitative and qualitative determination of medicated hair preparation.

Determination of Histamine H3-Receptor Antagonist Conessine in Wistar Rat Plasma by a Rapid and Sensitive RP-UFLC Method: Application to a Pharmacokinetic Study

Objectives: Epidemiological data suggests the highest density of histamine H3-receptors (H3R) in basal ganglia of central nervous system (CNS) wherein they function as inhibitory auto-receptors and control the release of many neurotransmitters. Inhibition of H3R increases the turnover of neurotransmitters, especially dopamine in basal ganglia and could be beneficial to treat Parkinson’s disease. Methods: In this study, we formulated the brain targeting liposomes of conessine, a selective antagonist for H3R to increase bioavailability and developed and validated a rapid and sensitive reverse phase ultra-force liquid chromatographic (RP-UFLC) method and to quantitate conessine in Wistar rat plasma and tissue. Plasma and tissue samples were extracted by protein precipitation technique using acetonitrile (ACN) and aripiprazole as the internal standard. Chromatographic separation was performed on the Hibar C18 column with a mobile phase of Hexane Sulphonic acid (10 mM, pH 10.0 adjusted with ammonia) and methanol at a flow rate of 0.9 ml/min. Results: The lower limit of quantification of the developed method was 4.0 ng/ml and 6.0 ng/g in plasma and tissue samples, respectively. Liposomes of conessine (equivalent to 20 mg/kg) administered orally to animals, demonstrated remarkable absorption into the systemic circulation with maximum concentration (~8700 ng/ ml) within 2.0 h. The order of area under curve was found to be kidney> brain> liver> lungs> spleen> heart. Conclusion: The liposomes of conessine were rapidly taken up into the brain and showed a good brain concentration after 2.0 h; sustenance up to 4.0 h was achieved which is better than conessine solution. Key words: Conessine, RP-UFLC method, Pharmacokinetic, Tissue distribution, Validation.

Bioanalytical LC-MS/MS method for Determination and comparison of Selexipag Assay in various Biological materials and its Application to Pharmacokinetics Studies in Rat plasma

A rapid, sensitive and selective bioanalytical method was developed and validated by Liquid Chromatography - Mass spectrometry (LC-MS/MS) for determination and comparison of Selexipag% assay in various biological materials. Selexipag wasextractedand compared its % assay after protein precipitation technique from various biological materials such as rat plasma, rabbit plasma, human plasma and urine. Ambrisentan was selected as internal standard. Selected analytical column Waters, X-Bridge C18 3.5µ (50 x 4.6 mm), mobile phase consists of Hexane sulfonic acid and Acetonitrile (80:20 v/v) at a flow rate of 1.0 mL /minin isocratic modeand Selexipag was determined by the +ve mode of electrospray ionization by using Mass detector. The method was developed to assess the lowerlimit of detection (LLOD)(0.5 ng/mL), lower limit of quantification(LLOQ) (5 ng/mL) concentrations and Linearity range of 1 ng/mL to 20 ng/mLconcentration with regression correlation coefficient 0.999 were observed for Selexipag in Rat plasma. The test samples at lower, medium and higher concentrationsof Selexipag shows precision (% CV was 0.8 to 1.11) and accuracy results (97.3 % to 100.6%) for inter-day and intra-day analysis at0.5, 5, 10, 15 ng/mL concentrationsof Selexipag. Appreciable recoveries for Selexipag were observed when extracted in Rat plasma compared with other biological materials. Stability of Selexipag exists in all conditions like wet extract, bench top, freeze-thaw and in instrument auto sampler as per FDA guidelines. This method indicates good results of accuracy, precision, linearity, recovery, stability and pharmacokinetic studies in rat plasma for clinical trials.

Stability Indicating HPLC Method for Simultaneous Estimation of Nicotinamide and Salicylic Acid

The purpose of the present study was to develop stability indicating HPLC method for simultaneous estimation of Nicotinamide and Salicylic acid and to validate developed method in accordance with ICH guidelines. Stability indicating reverse phase high performance liquid chromatography method was developed for Nicotinamide and Salicylic acid. Various trials with aqueous phase and organic phase were performed and mobile phase was optimized. The separation was achieved using Chromatopak C-18 (250mm x 4.6 mm, 5 µm) column, mobile phase containing Methanol and Water (0.1% TEA and 0.15 gm Hexane sulphonic acid and pH 3.0 adjusted with Glacial acetic acid) in the ratio of (40:60 v/v), at a flow rate of 1.0 ml/min. The retention time for Nicotinamide and Salicylic acid was 4.343 min and 17.673 min respectively. Forced degradation study was performed by applying stress conditions like acid hydrolysis, alkali hydrolysis, and neutral hydrolysis, and oxidation, thermal and photolytic degradation. %degradation was calculated with respect to drugs and specificity.LC method was validated by ICH Q2 (R1) guideline. The linearity was observed in the concentration range of 225-315 μg/ml for Nicotinamide and 75-105 μg/ml for Salicylic acid. The correlation coefficient was found to be 0.9971 and 0.9985 for Nicotinamide and Salicylic acid respectively. Degradation in all conditions was found to be 10 -20%. The method specifically estimates both the drugs in the presence of all the degradant generated during forced degradation study. The developed method was specific and precise and can be used for simultaneous estimation of Nicotinamide and Salicylic acid.

Novel Ion Pair HPLC Methods for the Assessment of Sitagliptin and Pioglitazone in Tablets

Objective: Developing simple, rapid and accurate ion-pair reversed phase high performance liquid chromatographic methods for the determination of pioglitazone hydrochloride, and sitagliptin phosphate in pure and tablet forms. These methods would be practical additional choices in quality control laboratories. Methods: pioglitazone hydrochloride and sitagliptin phosphateanalysis were performed depending on (Method A), the chromatographic conditions comprised of a classical C18-type stationary phase (250×4.6 mm, 5µm), The mobile phase consisting of 10-2 sodium hexane sulfonic acid, in a mixture of 550ml of deionized water and 450ml of acetonitrile, and apparent pH of 2.5 was adjusted with phosphoric acid. (Method B) is an additional method for pioglitazone hydrochloride analysis, the mobile phase consisting of 10-3 M cetrimide, in a mixture of 400 ml of deionized water and 600ml of acetonitrile, leading to measured pH=10. The flow rate was 1ml/min, the detection wavelengths were at 269nm for pioglitazone HCl (Method A,B), and 267nm for sitagliptin phosphate, the temperature was ambient temperature for both Methods A and B. Results: Two methods were validated in accordance to ICH guidelines. The developed methods given accepted linearity (R2>0.999) in the concentration range of (0.01875-0.21)mg/ml for pioglitazone hydrochloride and (0.1-0.6) mg/ml for sitagliptin phosphate, accuracy with mean recovery values between 98-102%, precision with relative standard deviations of the calculated concentrations were less than 2%. Conclusion: The results showed that the two developed methods were effective in separating and determining of pioglitazone HCl, sitagliptin phosphate in their pharmaceutical forms and routine analysis in quality control laboratories simply.

Inhibitory Effect of Taurine on Biofilm Formation During Alkane Degradation in Acinetobacter oleivorans DR1.

Taurine, 2-aminoethanesulfonate, is known to function as an antioxidant or membrane stabilizer in eukaryotic cells, but its role in bacteria has been poorly characterized. Biofilm formation of Acinetobacter oleivorans DR1 was significantly reduced by taurine only during alkane degradation, suggesting that taurine affects alkane-induced cell surface. Structurally similar compounds harboring an amine group such as hypotaurine or ethylenediamine have a similar effect, which was not observed with sulfonate-containing chemicals such as ethanesulfonic acid, hexanesulfonic acid. Our biochemical assays and physiological tests demonstrate that taurine reduced cell surface hydrophobicity, which resulted in interruption of the interactions between cells and oily substrate surfaces, such that cells utilized alkanes less effectively. Interestingly, taurine-mediated reduction of quorum sensing (QS) signal production and QS-control sapA gene expression indicated that membrane permeability of quorum signals was also interfered by taurine. Composition and biomass of extracellular polymeric saccharides were changed in taurine-amended conditions. Taken together, our data provide evidence that amine-containing taurine can inhibit biofilm formation of DR1 cells during alkane degradation by (i) changing cell surface charge and (ii) reducing membrane hydrophobicity and QS sensing.

An ultra-sensitive method for the analysis of perfluorinated alkyl acids in drinking water using a column switching high-performance liquid chromatography tandem mass spectrometry

In epidemiological research, it has become increasingly important to assess subjects’ exposure to different classes of chemicals in multiple environmental media. It is a common practice to aliquot limited volumes of samples into smaller quantities for specific trace level chemical analyses. A novel method was developed for the determination of 14 perfluorinated alkyl acids (PFAAs) in small volumes (10mL) of drinking water using off-line solid phase extraction (SPE) pre-treatment followed by on-line pre-concentration on a WAX column before analysis on column-switching high performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS). In general, large volumes (100–1000mL) have been used for the analysis of PFAAs in drinking water. The current method requires approximately 10mL of drinking water concentrated by using an SPE cartridge and eluted with methanol. A large volume injection of the extract was introduced on to a column-switching HPLC–MS/MS using a mix-mode SPE column for the trace level analysis of PFAAs in water. The recoveries for most of the analytes in the fortified laboratory blanks ranged from 73±14% to 128±5%. The lowest concentration minimum reporting levels (LCMRL) for the 14 PFAAs ranged from 0.59 to 3.4ng/L. The optimized method was applied to a pilot-scale analysis of a subset of drinking water samples from an epidemiological study. These samples were collected directly from the taps in the households of Ohio and Northern Kentucky, United States and the sources of drinking water samples are both surface water and ground water, and supplied by different water distribution facilities. Only five PFAAs, perfluoro-1-butanesulfonic acid (PFBS), perfluoro-1- -hexanesulfonic acid (PFHxS), perfluoro-1-octanesulfonic acid (PFOS), perfluoro-n-heptanoic acid (PFHpA) and perfluoro-n-octanoic acid (PFOA) are detected above the LCMRL values. The median concentrations of these five PFAAs detected in the samples was ≤4.1ng/L with PFOS at 7.6ng/L and PFOA at 10ng/L. Concentrations of perfluoro-1-decanesulfonic acid, PFDS and other perfluoroalkyl carboxylic acids were below the LCMRL values.

Development of a Single Ion Pair HPLC Method for Analysis of Terbinafine, Ofloxacin, Ornidazole, Clobetasol, and Two Preservatives in a Cream Formulation: Application to In Vitro Drug Release in Topical Simulated Media-Phosphate Buffer Through Rat Skin.

Present work reports an HPLC method with UV detection for quantification of terbinafine, ofloxacin, ornidazole, and clobetasol in a cream formulation along with two preservatives methyl and propyl paraben. The chromatographic separation and quantification was achieved by an octyl bonded column and a gradient elution program involving an ion-pairing reagent, hexanesulfonic acid (0.2%, pH modified to 2.7 using orthophosphoric acid) and acetonitrile. The method was simple and devoid of buffer salts and therefore advantageous for system and column life. The three step gradient program was initiated with 30% (v/v) acetonitrile for the first 5 min and ramped linearly to 60% in the next 7 min. The mobile phase remained constant for the next 11 min and then concluded at 30% (v/v) of acetonitrile. Flow rate throughout was 0.8 mL/min, and all the signals were monitored at 243 nm. The method was applied for assay of a cream formulation and its in vitro permeation studies to determine the penetration profile of the four drugs and two preservatives. A marketed cream formulation was selected for the permeation study, which was carried out using a diffusion cell consisting of topical simulated media, phosphate buffer (pH=6.8) solution containing 1% sodium lauryl sulfate as a receiver medium.

Surface Protection of Carbon Steel by Hexanesulphonic Acid-Zinc Ion System

Inhibition of corrosion of carbon steel in dam water by hexanesulphonic acid as its sodium salt C6H13SO3Na (SHXS) in the absence and presence of a bivalent cation zinc ion (Zn2þ) has been investigated using weight loss method. Results of weight loss method indicate that inhibition efficiency (IE) increased with increase of inhibitor concentration. Polarization study reveals that SHXS-Zn2+system controls the cathodic reaction predominantly. AC impedance spectra reveal that a protective film is formed on the metal surface. The nature of the metal surface has been analysed by Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Force Microscopy (AFM).

Effects of LDH synthesis and modification on the exfoliation and introduction of a robust anion-exchange procedure

Layered double hydroxides (LDHs) were synthesized and modified with different methods and also with different functional molecules. An easy and successful one-pot anion-exchange intercalation procedure was introduced and the influencing parameters of the modification were investigated in comparison to other modification methods. LDH based polymer nanocomposites were prepared with a microcompounder using melt-mixing method. The exfoliation behavior of organomodified LDHs was investigated with two different rheological models and visualized with electron microscopy techniques. Some of the relations between modification of LDH and the extent of exfoliation were identified. Highly exfoliated nanocomposites were successfully prepared after intercalation even with a small molecule like hexanesulfonic acid by performing the introduced anion exchange method.

STABILITY INDICATING HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF METOPROLOL SUCCINATE AND TELMISARTAN

A simple, rapid, accurate, precise, selective, and reproducible stability‐indicating HPLC method has been developed for simultaneous estimation of metoprolol succinate and telmisartan using a mobile phase consisting mixture of Methanol: 10 mM potassium dihydrogen phosphate buffer: 10 mM hexane sulphonic acid (80:10:10,v/v/v) at the flow rate of 1 mL/min and detection wavelength at 223.0 nm. HiQ Sil C18 (250 × 4.6 mm, 5 µm) column was used as stationary phase. The retention time for metoprolol succinate and telmisartan were 3.067 min and 5.653 min, respectively. Linearity was observed in the concentration range of 5–80 µg/mL for metoprolol succinate and 5–60 µg/mL for telmisartan. The coefficient of correlation for metoprolol succinate and telmisartan was found to be 0.9990 and 0.9980, respectively. The results of analysis have been validated statistically and by recovery studies. Both the drugs were subjected to acid, alkali and neutral hydrolysis, oxidation, dry heat, and photolytic degradation. The degradation products of telmisartan and metoprolol succinate were well resolved from the pure drugs with significant differences in the retention time values. This method can be successfully employed for simultaneous quantitative analysis of metoprolol succinate and telmisartan in bulk drugs and formulations.