scholarly journals Determination of absolute molecular weight of regioregular poly(3-hexylthiophene) by1H-NMR analysis

2016 ◽  
Vol 55 (1) ◽  
pp. 79-82 ◽  
Author(s):  
Dushanthi S. Dissanayake ◽  
Elena Sheina ◽  
Michael C. Biewer ◽  
Richard D. McCullough ◽  
Mihaela C. Stefan
Keyword(s):  
Molecular Weight ◽  
Nmr Analysis ◽  
Regioregular Poly

Determination of Some Nitrophenols by Atomic Absorption Spectrometry (AAS) After Extraction of Ionic Associates Involving the Bipyridylocopper(II) or Phenanthrolinocopper(II) Complex

1994 ◽  
Vol 59 (10) ◽  
pp. 2227-2234 ◽  
Author(s):  
Václav Stužka ◽  
Jaromír Souček
Keyword(s):  
Molecular Weight ◽  
Atomic Absorption Spectrometry ◽  
Atomic Absorption ◽  
Methyl Isobutyl Ketone ◽  
Absorption Spectrometry ◽  
Methyl Isobutyl ◽  
Isobutyl Ketone ◽  
Indirect Determination ◽  
Ionic Associates

A new method has been developed for the indirect determination of nitroso- and nitrophenols by atomic absorption spectrometry (AAS) after extraction of ionic associates involving bipyridylocopper(II) (CuDP) or phenanthrolinocopper(II) (CuPH) complexes. Nitrobenzene and methyl isobutyl ketone appeared to be suitable for the extraction. It was possible to determine several tenths to hundredths of a milligram of nitrophenol in a litre. Extractable associates with CuDP and CuPH are formed by phenols possessing two substituents or by higher molecular weight phenols such as naphthol or hydroxyquinoline. Monosubstituted phenols fail to form associates of this kind.

scholarly journals Structural Characterization of a Polysaccharide from Gastrodia elata and Its Bioactivity on Gut Microbiota

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4443
Author(s):  
Jiangyan Huo ◽  
Min Lei ◽  
Feifei Li ◽  
Jinjun Hou ◽  
Zijia Zhang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Citric Acid ◽  
Gut Microbiota ◽  
Structural Characterization ◽  
Hot Water ◽  
Nmr Analysis ◽  
Gastrodia Elata ◽  
Hot Water Extraction ◽  
Hydroxybenzyl Alcohol

A novel homogeneous polysaccharide named GEP-1 was isolated and purified from Gastrodia elata (G. elata) by hot-water extraction, ethanol precipitation, and membrane separator. GEP-1, which has a molecular weight of 20.1 kDa, contains a polysaccharide framework comprised of only glucose. Methylation and NMR analysis showed that GEP-1 contained 1,3,6-linked-α-Glcp, 1,4-linked-α-Glcp, 1,4-linked-β-Glcp and 1,4,6-linked-α-Glcp. Interestingly, GEP-1 contained citric acid and repeating p-hydroxybenzyl alcohol as one branch. Furthermore, a bioactivity test showed that GEP-1 could significantly promote the growth of Akkermansia muciniphila (A. muciniphila) and Lacticaseibacillus paracasei (L.paracasei) strains. These results implied that GEP-1 might be useful for human by modulating gut microbiota.

scholarly journals Simultaneous Determination of Human Serum Albumin and Low-Molecular-Weight Thiols after Derivatization with Monobromobimane

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3321
Author(s):  
Katarzyna Kurpet ◽  
Rafał Głowacki ◽  
Grażyna Chwatko
Keyword(s):  
Molecular Weight ◽  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Simultaneous Determination ◽  
Reversed Phase ◽  
Fluorescence Labeling ◽  
Detector Response ◽  
Low Molecular Weight

Biothiols are extremely powerful antioxidants that protect cells against the effects of oxidative stress. They are also considered relevant disease biomarkers, specifically risk factors for cardiovascular disease. In this paper, a new procedure for the simultaneous determination of human serum albumin and low-molecular-weight thiols in plasma is described. The method is based on the pre-column derivatization of analytes with a thiol-specific fluorescence labeling reagent, monobromobimane, followed by separation and quantification through reversed-phase high-performance liquid chromatography with fluorescence detection (excitation, 378 nm; emission, 492 nm). Prior to the derivatization step, the oxidized thiols are converted to their reduced forms by reductive cleavage with sodium borohydride. Linearity in the detector response for total thiols was observed in the following ranges: 1.76–30.0 mg mL−1 for human serum albumin, 0.29–5.0 nmol mL−1 for α-lipoic acid, 1.16–35 nmol mL−1 for glutathione, 9.83–450.0 nmol mL−1 for cysteine, 0.55–40.0 nmol mL−1 for homocysteine, 0.34–50.0 nmol mL−1 for N-acetyl-L-cysteine, and 1.45–45.0 nmol mL−1 for cysteinylglycine. Recovery values of 85.16–119.48% were recorded for all the analytes. The developed method is sensitive, repeatable, and linear within the expected ranges of total thiols. The devised procedure can be applied to plasma samples to monitor biochemical processes in various pathophysiological states.

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