scholarly journals Absolute optical chiral analysis using cavity-enhanced polarimetry

2021 ◽  
Author(s):  
Lykourgos Bougas ◽  
joseph byron ◽  
Dmitry Budker ◽  
Jonathan Williams
Keyword(s):  
Quality Control ◽  
Enantiomeric Excess ◽  
Chiral Analysis ◽  
In Situ Observation ◽  
Complex Environments ◽  
Gaseous Mixtures ◽  
Counterfeit Goods ◽  
Chiral Compounds ◽  
Online Quality Control ◽  
Pharmaceutical Industries

Chiral analysis is central for scientific advancement in the fields of chemistry, biology, and medicine. It is also indispensable in the development and quality control of chiral compounds in the chemical and pharmaceutical industries. Current methods for chiral analysis, namely optical polarimetry, mass spectrometry and nuclear magnetic resonance, are either insensitive, have low time resolution, or require preparation steps, and so are unsuited for monitoring chiral dynamics within complex environments: the current need of both research and industry. Here we present the concept of absolute optical chiral analysis, as enabled by cavity-enhanced polarimetry, which allows for accurate unambiguous enantiomeric characterization and enantiomeric-excess determination of chiral compounds within complex mixtures at trace levels, without the need for calibration, even in the gas phase. The utility of this approach is demonstrated by post chromatographic analysis of complex gaseous mixtures, the rapid quality control of perfume mixtures containing chiral volatile compounds, and the online in-situ observation of chiral volatile emissions from a plant under stress. Our approach and technology offer a step change in chiral compound determination, enabling online quality control of complex chemical mixtures, identification of counterfeit goods, detection of pests on plants, and assessment of chiral emission processes from climate relevant ecosystems.

Room Temperature Flow Electrochemistry as a Means of Retaining the “Memory of Chirality” via Hofer Moest Type Reaction

2020 ◽  
Author(s):  
Tomas Hardwick ◽  
Rossana Cicala ◽  
Nisar Ahmed
Keyword(s):  
Continuous Flow ◽  
Room Temperature ◽  
Biological Activities ◽  
Supporting Electrolyte ◽  
Enantiomeric Excess ◽  
Flow Chemistry ◽  
Batch Processes ◽  
Enabling Technology ◽  
Chiral Compounds ◽  
Memory Of Chirality

<p>Many chiral compounds have become of great interest to the pharmaceutical industry as they possess various biological activities. Concurrently, the concept of “memory of chirality” has been proven as a powerful tool in asymmetric synthesis, while flow chemistry has begun its rise as a new enabling technology to add to the ever increasing arsenal of techniques available to the modern day chemist. Here, we have employed a new simple electrochemical microreactor design to oxidise an L-proline derivative at room temperature in continuous flow. Flow performed in microreactors offers up a number of benefits allowing reactions to be performed in a more convenient and safer manner, and even allow electrochemical reactions to take place without a supporting electrolyte due to a very short interelectrode distance. By the comparison of electrochemical oxidations in batch and flow we have found that continuous flow is able to outperform its batch counterpart, producing a good yield (71%) and a better enantiomeric excess (64%) than batch with a 98% conversion. We have, therefore, provided evidence that continuous flow chemistry has the potential to act as a new enabling technology to replace some aspects of conventional batch processes. </p>

Simultaneous determination of the concentration and enantiomeric excess of amino acids with a coumarin-derived achiral probe

2021 ◽  
Vol 13 (16) ◽  
pp. 1905-1910
Author(s):  
Lamei Yang ◽  
Feng Luo ◽  
Weili Wei
Keyword(s):  
Amino Acids ◽  
Simultaneous Determination ◽  
Enantiomeric Excess ◽  
Chiral Analysis

An achiral easy-to-synthesize coumarin aldehyde probe was designed and synthesized for chiral analysis of amino acids.

Online quality control of laser welding using supporting line-shaped IR detection

1999 ◽  
Author(s):  
Hans K. Toenshoff ◽  
Ferdinand von Alvensleben ◽  
Andreas Ostendorf ◽  
Oliver Hillers ◽  
Matthias Stallmach
Keyword(s):  
Quality Control ◽  
Laser Welding ◽  
Supporting Line ◽  
Online Quality Control ◽  
Ir Detection

scholarly journals A new twist in eutectic composition: deracemization of a racemic compound amino acid by Viedma ripening and temperature fluctuation.

2021 ◽  
Author(s):  
CRISTOBAL VIEDMA ◽  
José Eugenio Ortíz
Keyword(s):  
Temperature Fluctuation ◽  
Solid Phase ◽  
Enantiomeric Excess ◽  
Eutectic Mixture ◽  
Chiral Molecules ◽  
Racemic Compound ◽  
Chiral Compounds ◽  
First Case ◽  
New Finding ◽  
New Ideas

Viedma ripening and temperature fluctuation are processes based on solution phase racemization and dissolution-growth of racemic or scalemic conglomerates resulting in solid-phase deracemization. The dissolution-growth process is performed by abrasive grinding in the first case and by the temperature fluctuation in the second. But both methods have the intrinsic drawback of being only applicable to conglomerates, accounting for only 10% of all chiral molecules and are not suitable for the 90% of chiral compounds that crystallize as racemic compound. Herein we show that the enantiomeric excess of the solution in the eutectic mixture formed by a racemic compound and one of its enantiomers in suspension changes dramatically by growth-dissolution of the crystals through grinding and temperature fluctuation, converting the racemic compound into the desired enantiomer. With this new finding the scope of Viedma ripening and temperature fluctuation could be significantly expanded and can shed new ideas about the origin of biological homochirality on earth.

Online Quality Control, Hyperfractionated Radiotherapy Alone and Reduced Boost Volume for Standard Risk Medulloblastoma: Long-Term Results of MSFOP 98

2009 ◽  
Vol 27 (11) ◽  
pp. 1879-1883 ◽  
Author(s):  
Christian Carrie ◽  
Jacques Grill ◽  
Dominique Figarella-Branger ◽  
Valerie Bernier ◽  
Laetitia Padovani ◽  
...  
Keyword(s):  
Overall Survival ◽  
Quality Control ◽  
Full Scale ◽  
Cognitive Outcomes ◽  
Long Term Results ◽  
Hyperfractionated Radiotherapy ◽  
Tumor Bed ◽  
Online Quality Control ◽  
Standard Risk

Purpose To determine event free and overall survival, and long-term cognitive sequelae of children with standard-risk medulloblastoma (SRM) treated with hyperfractionated radiotherapy, conformal reduced boost volume without chemotherapy, and online quality assurance. Patients and Methods Forty-eight patients (age 5 to 18 years) were included in the Medulloblastoma-Société Française d'Oncologie Pédiatrique (MSFOP 98) protocol (December 1998 to October 2001). Patients received hyperfractionated radiotherapy (HFRT; 36 Gy, 1 Gy/fraction twice per day) to the craniospinal axis followed by a boost to the tumor bed (1.5-cm margin) to a dose of 68 Gy. Records of craniospinal irradiation were reviewed before treatment started. Neuropsychologic evaluations were done according to the protocol (1, 3, 5, and 7 years after irradiation). Cognitive outcomes were followed longitudinally with full-scale intelligence quotient (FSIQ) obtained with age-adapted Wechsler scales. Results After a median follow-up of 77.7 months, 6-year overall survival (OS) and event-free survival (EFS) rates for the cohort were 78% (95% CI, 66% to 90%) and 75%, respectively (95% CI, 62% to 87%). Thanks to quality control, 14 major deviations were detected. Annual full scale IQ decline was 2 points over a 6-year period. Predicted change in FSIQ points per year was 2.15 (95% CI, −1.24 to 3.51) with an intercept (ie, predicted FSIQ) of 93.57 at baseline. Conclusion HFRT protocol with conformal reduced boost and online quality control allows excellent long-term OS and EFS in the absence of chemotherapy. In addition, FSIQ drops seem to be less pronounced than previously reported with standard irradiation regimens.

Fast Determination of Active Components in Fructus Corni by Near Infrared Spectroscopy

2013 ◽  
Vol 807-809 ◽  
pp. 2054-2058
Author(s):  
Hai Yan Gong ◽  
Ya Nan Hu ◽  
Cai Xia Xie ◽  
Yong Xia Cui ◽  
Yan Bai
Keyword(s):  
Quality Control ◽  
Infrared Spectroscopy ◽  
Mean Square Error ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Calibration Model ◽  
Mean Square ◽  
Active Components ◽  
Near Infrared Reflectance ◽  
Pharmaceutical Industries

Today, near-infrared (NIR) has been proved to be a powerful analytical tool. It has been applied widely in agricultural, petrochemical, textile and pharmaceutical industries. In this paper, near-infrared spectroscopy (NIRS) combined with partical least square (PLS) was used as a qualitative tool to rapidly determinate two active components in Fructus Corni. The PLS calibration model of NIR Spectroscopy, the correlation coefficients (R2) of Loganin and Morroniside were 0.95895 and 0.98450, the root-mean-square error of cross-validation (RMSECV), the Correction of deviation, the prediction mean square error was 0.0344,0.109;0.0625, 0.2641 and 0.0948, 0.233. The result shows that, the near-infrared Reflectance Spectroscopy could be used to determinate the content of Loganin and Morroniside, and meanwhile as a simple and rapid new method for the quality assessment of Fructus Corni. In addition, the NIRS has a unique advantage in the quality control of traditional Chinese Medicine (TCM), such as rapid, accurate, nondestructive and no pollution. It is expected to be further uses in the quality control of TCM. It is can achieve the requirement of rapid detection of large quantities of Fructus Corni.

scholarly journals Recent Development of Quality Control Methods for Herbal Derived Drug Preparations

2018 ◽  
Vol 13 (12) ◽  
pp. 1934578X1801301 ◽  
Author(s):  
Gunawan Indrayanto
Keyword(s):  
Quality Control ◽  
Raw Materials ◽  
Herbal Medicines ◽  
Complex Nature ◽  
Chemical Marker ◽  
Chemical Profiling ◽  
Chemical Content ◽  
Pharmaceutical Industries ◽  
Microbial Toxins

Pharmaceutical industries should apply rigorous QC (quality control) to ensure the consistency, safety, and efficacy of their herbal derived drug-preparations. QC must be performed at every stage of the production line i.e. incoming raw materials, extractions, in-process control, finished products and keeping samples. Due to the complex nature of the chemical content of herbal drugs, two approaches to QC should be taken, that is quantitative determination of the selected marker(s) compound(s), and metabolite profiling. Contamination of herbal medicines by heavy metals, pesticides, toxic metabolites, microbial toxins, pathogenic microorganisms and other foreign matter should also be evaluated. A combination of chemical profiling and multivariate analysis (MVA) is recommended as the QC tool for the botanical identification method (BIM) of herbs, extracts, herb materials, and herbal drug preparations. Microscopic methods, DNA profiling or chemical marker(s) are not recommended for use as the sole BIM due to the lack of specificity. Only markers that meet certain criteria i.e. quality active (QA) markers can be utilized as a QC tool. The limit specification range of markers used as QC tools should be described in the analytical target profile (ATP). To gain reliable results of any analysis that has been performed at any QC laboratory, the analysis method must be validated according to the newest guidance. Sample detection limit of any toxic compound(s) should be lower than its cut-off value and MPL. The reliability of any results of analysis of a QC laboratory must be evaluated by using QC-samples for each series of measurements.

An efficient asymmetric approach to the R-enantiomer impurity of esomeprazole

2016 ◽  
Vol 22 (1) ◽  
pp. 17-19
Author(s):  
Guobin Zhou ◽  
Yueqing Guan
Keyword(s):  
Quality Control ◽  
Proton Pump Inhibitor ◽  
Proton Pump ◽  
Enantiomeric Excess ◽  
Antiulcer Drug ◽  
Asymmetric Oxidation ◽  
C Nmr

AbstractEsomeprazole {(S)-5-methoxy-2-[(4-methoxy-3, 5-dimethyl-2-pyridinylmethyl) sulfinyl]-1H-benzimidazole} is a proton pump inhibitor used as an antiulcer drug. Its R-enantiomer 3 was synthesized with high enantioselectivity by asymmetric oxidation of prochiral sulfide 2 using the oxaziridinium salt 4. Product 3, useful as a reference for the quality control of esomeprazole, was characterized by 1H and 13C NMR, IR, and HRMS. The enantiomeric excess was determined by HPLC.

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