Purification of closely eluting hydrophobic microcystins (peptide cyanotoxins) by normal-phase and reversed-phase flash chromatography

1999 ◽  
Vol 848 (1-2) ◽  
pp. 515-522 ◽  
Author(s):  
Linda A Lawton ◽  
Jacqui McElhiney ◽  
Christine Edwards
Keyword(s):  
Reversed Phase ◽  
Normal Phase ◽  
Flash Chromatography

scholarly journals Continuous synthesis of bromoalkyl glycosides by Fischer glycosylation in a microreactor

2021 ◽  
Author(s):  
Jessica Jung ◽  
Lars Kaiser ◽  
Hans-Peter Deigner ◽  
Magnus S. Schmidt
Keyword(s):  
Reversed Phase ◽  
Normal Phase ◽  
Flash Chromatography ◽  
Reaction Conditions ◽  
Continuous Synthesis ◽  
Acidic Catalysts

Abstract In this study, bromoalkyl glycosides were successfully synthesized in microreactor scale by Fischer glycosylation. Yields between 24 and 40% after purification were achieved using various acidic catalysts and conditions. In some experiments, yields 180% higher than with previously known methods could be achieved. This study showed also that reversed-phase flash chromatography is more successful than normal-phase flash chromatography for the purification of bromoalkyl glycosides. Furthermore, longer bromoalcohols were shown to be more compatible than shorter bromoalcohols under these reaction conditions.

scholarly journals Combining Normal/Reversed-Phase HPTLC with Univariate Calibration for the Piperine Quantification with Traditional and Ultrasound-Assisted Extracts of Various Food Spices of Piper nigrum L. under Green Analytical Chemistry Viewpoint

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 732
Author(s):  
Mohammed H. Alqarni ◽  
Prawez Alam ◽  
Ahmed I. Foudah ◽  
Magdy M. Muharram ◽  
Faiyaz Shakeel
Keyword(s):  
Analytical Chemistry ◽  
High Performance ◽  
Black Pepper ◽  
Reversed Phase ◽  
Normal Phase ◽  
Piper Nigrum ◽  
Green Analytical Chemistry ◽  
Pharmaceutical Samples ◽  
Analytical Technique ◽  
Ultrasound Assisted

Due to unavailability of sustainable analytical techniques for the quantitation of piperine (PPN) in food and pharmaceutical samples, there was a need to develop a rapid and sensitive sustainable analytical technique for the quantitation of PPN. Therefore, the current research presents a fast and highly sensitive normal/reversed-phase high-performance thin-layer chromatography (HPTLC) technique with classical univariate calibration for the quantitation of PPN in various food spices of black pepper with traditional (TE) and ultrasound-assisted extracts (UBE) of various food spices of Piper nigrum L. under green analytical chemistry viewpoint. The amount of PPN in TE of four different spices of black pepper—namely BPMH, BPLU, BPSH, and BPPA—was found to be 309.53, 304.97, 282.82, and 232.73 mg g−1, respectively using a sustainable normal-phase HPTLC technique. However, the amount of PPN in UBE of BPMH, BPLU, BPSH, and BPPA was recorded as 318.52, 314.60, 292.41, and 241.82 mg g−1, respectively using a sustainable normal phase HPTLC technique. The greenness of normal/reversed-phase HPTLC technique was predicted using AGREE metric approach. The eco-scale was found to be 0.90, suggested excellent greenness of normal/reversed-phase technique. UBE of PPN was also found to be superior over TE of PPN. Overall, the results of this research suggested that the proposed normal/reversed-phase densitometry technique could be effectively used for the quantitation of PPN in food and pharmaceutical samples.

Elucidation of Carotenoid Patterns in Citrus Products by Means of Comprehensive Normal-Phase × Reversed-Phase Liquid Chromatography

2006 ◽  
Vol 78 (22) ◽  
pp. 7743-7750 ◽  
Author(s):  
Paola Dugo ◽  
Veronika Škeříková ◽  
Tiina Kumm ◽  
Alessandra Trozzi ◽  
Pavel Jandera ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Reversed Phase ◽  
Normal Phase ◽  
Reversed Phase Liquid Chromatography ◽  
Phase Liquid

scholarly journals Normal-phase thin-layer chromatography of some angiotensin converting enzyme (ACE) inhibitors and their metabolites

2009 ◽  
Vol 74 (6) ◽  
pp. 677-688 ◽  
Author(s):  
Jadranka Odovic ◽  
Mirjana Aleksic ◽  
Biljana Stojimirovic ◽  
Dusanka Milojkovic-Opsenica ◽  
Zivoslav Tesic
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Ace Inhibitors ◽  
Reversed Phase ◽  
Normal Phase ◽  
Converting Enzyme ◽  
Reversed Phase Chromatography ◽  
Aqueous Solvent ◽  
Layer Chromatography

The separation and chromatographic behaviour of five ACE (angiotensin converting enzyme) inhibitors and their four active metabolites were investigated by normal-phase thin-layer chromatography on silica using several mono- and binary non-aqueous solvent systems. The linear relationship between the RM values and the composition of employed mobile phase was obtained. The hydrophobicity parameters 0M R and C0 were determined from the regression data of the plots, analogous to reversed-phase chromatography. The chromatographically obtained hydrophobicity parameters were correlated with the calculated log P values. The current results were correlated with the lipophilicity of the studied ACE inhibitors and their metabolites, previously estimated by reversed-phase chromatography.

scholarly journals The Separation of Cannabinoids on Sub-2 µm Immobilized Polysaccharide Chiral Stationary Phases

2021 ◽  
Vol 14 (12) ◽  
pp. 1250
Author(s):  
Takafumi Onishi ◽  
Weston J. Umstead
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Stationary Phases ◽  
Chiral Stationary Phases ◽  
Reversed Phase ◽  
Normal Phase ◽  
Elution Order ◽  
Testing Methods ◽  
Structural Isomers

The increased use and applicability of Cannabis and Cannabis-derived products has skyrocketed over the last 5 years. With more and more governing bodies moving toward medical and recreational legalization, the need for robust and reliable analytical testing methods is also growing. While many stationary phases and methods have been developed for this sort of analysis, chiral stationary phases (CSPs) are unique in this area; not only can they serve their traditional chiral separation role, but they can also be used to perform achiral separations. Given that mixtures of cannabinoids routinely contain enantiomers, diastereomers, and structural isomers, this offers an advantage over the strictly achiral-only analyses. This work presents the separation of a 10-cannabinoid mixture on several polysaccharide-based sub-2 µm CSPs with both normal-phase and reversed-phase ultra-high-performance liquid chromatography (UHPLC) conditions. Along with the separation of the mixture, appropriate single-peak identification was performed to determine the elution order and reported where applicable.

Quantification of Vitamins A, E, and K and Carotenoids in Submilliliter Volumes of Human Milk

2019 ◽  
Vol 102 (4) ◽  
pp. 1059-1068 ◽  
Author(s):  
Antoine Levêques ◽  
Jean-Marie Oberson ◽  
Emeline Alexandra Tissot ◽  
Karine Redeuil ◽  
Sagar K Thakkar ◽  
...  
Keyword(s):  
Human Milk ◽  
Reversed Phase ◽  
Normal Phase ◽  
Reversed Phase Liquid Chromatography ◽  
Liquid Liquid Extraction ◽  
Nutritional Needs ◽  
Phase Liquid ◽  
Single Laboratory ◽  
Β Carotene

Abstract Background: Human milk is the optimal nutrition for all newborns in the first 6 months of life. In order to assess the nutritional needs of the breastfed infant, human milk is often characterized for multiple nutrients. Objective: To ensure that we minimize the volume of milk dedicated for research and optimize the number of nutrients characterized, we developed analytical methodologies for the determination of vitamins A (retinol), E (alpha and gamma tocopherol), K (phylloquinone and menaquinone-4), and five carotenoids (β-carotene, lycopene, β-cryptoxanthin, lutein, and zeaxanthin) using <1 mL human milk. Method: Vitamins E and K and carotenoids are simultaneously isolated from 750 μL milk by liquid–liquid extraction (LLE). Tocopherols and carotenoids are determined by normal-phase LC with fluorescence and ultraviolet detection respectively. Vitamin K is analyzed on the same extracts after resuspension and clean-up by reversed phase liquid chromatography coupled to tandem MS. The analysis of vitamin A involves saponification of 200 μL milk followed by LLE and determination by normal-phase LC with UV detection. Results: Full single-laboratory validation at four different concentration levels is presented. Recovery rates were within 90–105% in all except one case (retinol at 1.9 μg/mL, 88% recovery), with RSDs of repeatability and intermediate reproducibility below 10 and 15%, respectively for all the compounds. Conclusions and Highlights: To the best of best knowledge, this is the first report that allows for the characterization and quantification of vitamins A, E, and K and five carotenoids in <1 mL human milk.

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