Isolation and Structural Elucidation of Impurity in Sulfonamide Intermediate of Glyburide

A reproducible isolation method by Reverse Phase (RP) preparative HPLC technique for the isolation of one crucial impurity at 1.65 RRT (Relative Retention Time) in sulfonamide stage of Glyburide API (Active Pharmaceuticals Ingredient) was developed. Preparative chromatography was done on Luna C8, 10µm (250 mm x 21.2mm) preparative HPLC column with acetonitrile: water in 70:30 % v/v proportion as a mobile phase and 8 ml/min as a flow rate. This impurity was detected at 300 nm UV-wavelength maximum. This impurity was isolated from synthesized crude impurity of sulfonamide stage of Glyburide substance by preparative HPLC by injecting 50 mg/ml concentration over 5 ml fixed loop. Isolated impurity was elucidated as N-methyl impurity of sulfonamide intermediate of Glyburide API by means of chromatographic and spectral data. Structural elucidation carried out by spectral data was reviewed. This impurity was analyzed by reverse phase HPLC for purity analysis. A Inertsil C8 (250 x 4.6) mm, 5µ particle size was employed for separation. The mobile phase consisted of Water: Acetonitrile: Methanol in the ratio of 60:15:25 % v/v. The flow rate was set at 1 ml/min. Detection was carried out at 300 nm. 10µL of 2 mg/ml concentration of sample in methanol was injected. The column oven temperature was at 25°C.

Strategies to Enhance Retention in a Cohort Study Among Adults of Turkish Descent Living in Berlin

Retention is important for statistical power and external validity in long-term cohort studies. The aims of our study were to evaluate different retention strategies within a cohort study of adults of Turkish descent in Berlin, Germany, and to compare participants and non-participants. In 2011–2012, a population-based study was conducted among adults of Turkish descent to primarily examine recruitment strategies. 6 years later, the participants were re-contacted and invited to complete a self-report questionnaire regarding their health status, health care utilization, and satisfaction with medical services. The retention strategy comprised letters in both German and Turkish, phone calls, and home visits (by bilingual staff). We calculated the response rate and retention rate, using definitions of the American Association for Public Opinion Research, as well as the relative retention rate for each level of contact. Associations of baseline recruitment strategy, sociodemographic, migration-related and health-related factors with retention were investigated by logistic regression analysis. Of 557 persons contacted, 249 (44.7%) completed the questionnaire. This was 50.1% of those whose contact information was available. The relative retention rate was lowest for phone calls (8.9%) and highest for home visits (18.4%). Participants were more often non-smokers and German citizens than non-participants. For all remaining factors, no association with retention was found. In this study, among adults of Turkish descent, the retention rate increased considerably with every additional level of contact. Implementation of comprehensive retention strategies provided by culturally matched study personnel may lead to higher validity and statistical power in studies on migrant health issues.

Systematic Study on a Quantitative Analysis of Multicomponents by Single Marker (QAMS) Method for Simultaneous Determination of Eight Constituents in Pneumonia Mixture by UPLC-MS/MS

Pneumonia mixture was formulated and is available to treat children acute pneumonia and acute bronchitis in our hospital for nearly forty years, but there are few studies of its quality evaluation or control. In this paper, a new strategy for quality evaluation of pneumonia mixture was explored and verified through qualitative and quantitative analyses of multicomponents by single marker (QAMS) by UPLC-MS/MS. Baicalein was selected as an internal reference, and the relative correction factors (RCFs) and the relative retention time (RRT) of (R, S)-goitrin, amygdalin, chlorogenic acid, pseudoephedrine hydrochloride, ephedrine hydrochloride, ammonium glycyrrhizinate, and baicalin were established. The robustness and durability of the QAMS method were investigated. RCF values calculated by the average (AVG) method and linear regression (LRG) method had good repeatability and were acceptable for quantitative analysis, and the RTT combined with the exact masses of precursor and fragment ions and their abundance could be adopted for accurately positioning the chromatographic peak of the eight constituents. The consistency and feasibility of the QAMS method were verified by comparing the contents of the seven components calculated by a classic and validated external standard method (ESM) with those of the QAMS method, which reduces analytical cost and time of detection and avoids the problem of the diversity and large quantity of reference standards. The results demonstrated that the QAMS method developed in this paper could provide a new, alternative, and promising method to comprehensively and effectively determine multicomponents and control the quality of pneumonia mixture or even a group of similar medicines.

Better together – Relative retention time plus spectral matching improves automated glycan characterization using PGC-nLC-IT-ESI-MS/MS

Porous Graphitized Carbon nano-liquid chromatography tandem mass spectrometry (PGC-nLC-MS/MS) is a glycomics technique with the unique capacity to differentiate isobaric glycans. The lack of suitable software tools integrating chromatography and MS-information delivered by PGC-nLC-MS/MS has been limiting fast and robust glycan identification and quantitation. We report a LC-system-independent strategy called GlycoRRT that combines relative retention time (RRT) and negative ion fragment spectra analyses for isobaric structure-specific glycomics of PGC-nLC-MS/MS data. The GlycoRRT toolset is fully customizable and easily adaptable enabling semi-automated high-throughput structural assignments. The current library contains over 200 entries and their individual meta-data (MS instrumentation, experimental conditions, retention times, fragmentation profiles and glycan structural diagnostic ion features) relevant for reliable data analyses. The GlycoRRT workflow was employed to map the N- and O-glycome in blood group matched human plasma and urine as well as decipher Immunoglobulin (IgG) glycosylation features from 13 different animal species. We have also developed visualization tools to enable a consistent, reliable and reproducible analysis of large sets of multidimensional PGC-nLC-MS/MS glycomics data. This comprehensive glycan resource provides the glycan map of human and animal species, will serve as a reference in dissecting the role of glycans in host pathogen interaction and zoonotic disease transmission.

Substantiation of an approach to determination of ketoprofen macrogol 400 esters

The aim. The work is concerned with the substantiation of the approach to the identification and quantitative determination of ketoprofen macrogol 400 esters. Materials and methods. Ketoprofen, macrogol 400, ketoprofen macrogol 400 ester (KM400E), as well as model cream-gels were studied by the following methods: absorption spectrophotometry ultraviolet (UV) and visible, high-performance liquid chromatography (HPLC), gas chromatography (GC), GC / mass spectrometry, nuclear magnetic resonance (NMR) spectrometry and thermogravimetry. Results. It was found by GC and GC / mass spectrometry that the average molecular mass (Mr) of the test macrogol 400 is 383.50 and it contains oligomers with molecular masses from 150.17 to 546.65. KM400E, which is a mixture of esters of ketoprofen with macrogol oligomers, was synthesized. The formed esters were characterized by 1H NMR spectra. It was shown that the ratio of the average molecular mass of KM400E, calculated for monoesters, and the molecular mass of ketoprofen corresponds to the ratio of specific absorbances of solutions of ketoprofen and solutions of KM400E, this fact indicated the formation of monoesters. Taking into account the risk of variability of the fractional composition of macrogol 400 in different batches, it is advisable to quantify KM400E using ketoprofen reference standard (RS) and not KM400E RS. Using HPLC with diode array detection the peak of KM400E should be identified by the UV absorption spectrum with λmax≈255 nm, which is characteristic for ketoprofen, and the relative retention time (RRt) of the peak; KM400E should be quantified by the content of ketoprofen in this impurity. During storage of model cream-gels the content of KM400E impurity is significantly lower than the content of ketoprofen propylene glycol ester (mixture of isomers). Conclusions. The approach to the identification and quantitative determination of KM400E is substantiated. The analytical procedure for determination of KM400E impurity by HPLC with a diode array detection using ketoprofen RS was developed. Correctness of the procedure was proved by the results of the validation studies.

How Managerial Openness to Voice Shapes Internal Attraction: Evidence from UNITED STATES School Systems

In this study, the authors explore a heretofore unappreciated benefit of managerial openness to employee voice: internal attraction. Previous work has shown that managers who are more open to listening to employees receive valuable information and their units have higher relative retention levels. The authors explain and empirically demonstrate that managers who are more open to employee voice also more effectively attract workers from other units in their organizations. They describe how and why managerial openness to voice likely shapes the information that employees in a focal organizational unit (“employee insiders”) share with employees in other units (“employee outsiders”). They find that units with managers who are perceived as more open to voice are viewed as more attractive places to work. Conducting two field studies in separate US school districts, the authors find that managerial openness to voice positively predicts a work unit’s attractiveness among employees who work in other areas of the organization. They discuss the implications of their findings for organizations in general and school districts specifically.

Identification of Tartaric Acid Adduct Impurities in Dipyridamole Capsule Formulation Related Substances Method

Two tartaric acid adduct degradation products namely dipyridamole tartaric acid monoester and dipyridamole ditartaric acid ester are observed in a dipyridamole capsule formulation. The adduct impurities are inevitable in the formulation due to the interaction of multilayers of dipyridamole on tartaric acid pellets. Present study reported a simple procedure for generating these two major adducts degradation products from a mixture of dipyridamole drug substance and tartaric acid by stress study. The obtained stress mixture was characterized by liquid chromatography-tandem mass spectrometry (LC-MS) to assure the identity of adduct degradant impurities. The obtained solid stress mixture was stable for more than one year and the prepared solution can be used as reference solution to identify both the degradants during related substance analysis. Practically, the identification of tartaric acid degradants applied to the British pharmacopeia monograph related substances method, where no mechanism for identification of these adduct impurities was described. This study establishes relative retention times for the British pharmacopeia method, which enables the chemist to monitor these two major degradants during quality control release testing and shelf life stability. The same kind of experimental approach for identifying tartaric acid adduct impurities in the British pharmacopeia method can be extended to any of the in-house laboratory-developed related substance methods.

Stability-Indicating RP-HPLC Method for the Estimation of Process-Related Impurities and Degradation Products in Fesoterodine Fumarate by Using a Mass Spectrometric Compatible Mobile Phase

The objective of the present work was to develop a sensitive, selective, accurate and precise stability-indicating HPLC method for quantification of degradation products and process-related impurities in fesoterodine fumarate extended-release tablets. The degradation profile was studied by conducting forced degradation studies and all the degradation products formed during degradation were separated. A chromatographic separation was achieved by using Waters Symmetry C18, 250 × 4.6 mm, 5 μm column, maintained at 30°C. Mobile phase A (0.05% trifluoroacetic acid in water) and mobile phase B (90% of 0.02% TFA in methanol and 10% of water) were used in gradient elution mode. A total of 75 μL of each solution was injected and peak responses were quantified at 220 nm. The method was found specific, precise, accurate, linear, rugged, robust and sensitive. During stability studies of fesoterodine fumarate extended-release tablets, one unknown impurity at relative retention time 1.37 was found increasing beyond the identification threshold. This impurity was isolated by using Preparative HPLC and structure was elucidated using mass and NMR spectroscopy. This method is a simple, inexpensive HPLC method that can be used as a routine quality control test for the estimation of impurities in fesoterodine fumarate extended-release tablets.

Quality Assessment of Sitopaladi Churna Using High-Performance Liquid Chromatography Coupled with Multivariate Analysis

“Sitopaladi churna,” a well-known formulation of Ayurveda, is prescribed to treat the disease like Bronchitis, Pneumonia, allergic conditions, viral infection of the respiratory tract and as a natural antioxidant. A novel method based on reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to photodiode array detector was established and validated for sitopaladi churna. Here, HPLC fingerprints data obtained for 28 samples including standard sample were then treated to chemometric analysis like principal component analysis and hierarchical clustering analysis for further analysis to evaluate the differences in market samples of sitopaladi churna. Additionally, one major marker compound, piperine was quantified and it also facilitated for relative retention time. The simulative mean spectrum was also generated. The validation results showed that the developed method was simple, precise and stable. Thus, the developed chromatographic method adjoined with multivariate analysis can be used as an efficient and practical approach for quality assessment of sitopaladi churna.