Absorption Coefficients of Phenolic Structures in Different Solvents Routinely Used for Experiments

Abstract

Phenolic structures are of great interest due to their antioxidant properties and various postulated benefits on human health. However, the quantification of these structures in fruits and vegetables, as well as in vivo or in vitro experiments, is demanding, as relevant concentrations are often low, causing problems in exactly weighing the respective amounts. Nevertheless, the determination of used concentrations is often a prerequisite for accurate results. A possibility to quantify polyphenol is the use of UV/vis spectroscopy. Therefore, the absorption coefficients of selected phenolic structures were determined in three different solvents relevant for polyphenol research (water/methanol (50/50, v/v), water, and phosphate buffer at pH 7.5). To confirm the values based on weight and to avoid errors due to impurities, hygroscopic effects, and inadequate balance care, the mass concentrations were additionally determined by quantitative NMR (q-NMR). The coefficients presented in this article can help to quickly and easily determine accurate concentrations in a laboratory routine without wasting the often-precious standard compounds.

Neutral and Pectic Heteropolysaccharides Isolated from Opuntia joconostle Mucilage: Composition, Molecular Dimensions and Prebiotic Potential

“…To corroborate this finding, the SEC analysis delivered in the UV/VIS plot at 310 nm a prominent peak at 48 mL without any corresponding signal in the RI plot ( Figure A1 ). The wavelength of 310 nm was chosen as it is close to the absorption maximum of ferulic acid and its derivatives [ 23 ]. This peak is likely to be phenolics separated under the mild conditions of SEC.…”

Geographical and seasonal phytochemical variation of Artemisia afra Jacq. ex Willd

“…Interestingly, there was an interchangeable trend between CGA and DCQA observed in the samples collected monthly, with elevated levels of CGA during winter months and elevated levels of DCQA during summer months. A possible explanation is the difference in ultraviolet (UV) attenuation coefficient between CGA (18.3 ϵ) and DCQA (34.0 ϵ) at 329 and 330 nm, respectively, which implies DCQA, with a higher molar absorptivity, is biosynthesised during the summer months when UV radiation is generally higher 27 . De Lazzari et al 28 .…”

Ultrasound-Assisted Extraction of Polyphenols from Maritime Pine Residues with Deep Eutectic Solvents

“…The optimization of the USE method was based on extracting the maximum total polyphenols from pine residues. The extracts were analyzed at 280 nm, using a Genesys 10uv spectrophotometer (Thermo Scientific, Waltham, MA, USA), a wavelength where maximum absorbance is observed in polyphenols [ 35 ]. A gallic acid calibration curve was prepared between 0 and 800 mg/L and used as standard to estimate the total concentration of polyphenols.…”