Determination of polyphenolic compounds in Cirsium palustre (L.) extracts by high performance liquid chromatography with chemiluminescence detection

Neuraminidase Inhibitory Activity and Constituent Characterization of Fagopyrum dibotrys

“…Peak 11 was proposed to be 4- o -methyl-gallate, whose fragment ions were m / z 169 [M − H − CH 3 − CO 2 ] − , m / z 125 [M − CH 3 − CO 2 ] − [20]. Peak 21 had a molecular ion at m / z 197, and its fragment ions at m / z 169 and 125 were identified as [ethyl gallate − CH 3 CH 2 ] − , and [ethyl gallate − CH 3 CH 2 − CO 2 ] − , respectively.…”

Ultra-high Performance Liquid Chromatography with Photodiode Array and Chemiluminescence Detection for the Determination of Polyphenolic Antioxidants in Erigeron acris L. Extracts

“…One of the problems that could be observed in the post‐column CL detection is that the mobile phase is not compatible with applied CL reaction (some organic modifiers strongly quench the emission intensity). Our previous study (Nalewajko‐Sieliwoniuk et al , ) revealed that acetonitrile, contrary to methanol, caused strong inhibition of analytical signals of polyphenolic compounds measured by the post‐column manganese(IV)‐based CL detection. This effect was also observed by other researchers (e.g.…”

“…For the determination of polyphenolic compounds after their UHPLC separation the CL detection based on manganese(IV)–hexametaphosphate–formaldehyde system was used. A weak CL generated in this system is greatly enhanced by plant polyphenolic compounds (Malejko et al , ; Nalewajko‐Sieliwoniuk et al , ). Polyphenols are able to reduce manganese(IV) to an electronically excited manganese(II) species, which emit red radiation (725–740 nm) when returning to their ground state (Adcock et al , ).…”

“…According to the procedure described in our previous paper (Nalewajko‐Sieliwoniuk et al , ) 1.7 × 10 −3 mol/L nano‐colloidal manganese(IV) solution in 5 mol/L phosphoric acid (H 3 PO 4 ) (POCH, Gliwice, Poland) and containing 3% (w/v) sodium hexametaphosphate (Sigma‐Aldrich, Steinheim, Germany) was prepared. Briefly, manganese(IV) solution was obtained by dissolving freshly precipitated manganese dioxide (formed during the reaction of sodium formate (Sigma‐Aldrich, Steinheim, Germany) with potassium permanganate (POCH, Gliwice, Poland) in 5 mol/L H 3 PO 4 ).…”

“…For the post‐column CL detection of polyphenols manganese(IV)–formaldehyde–hexametaphosphate system was applied. In our previous papers (Malejko et al , ; Nalewajko‐Sieliwoniuk et al , ) it was found that this CL system enables sensitive detection of polyphenols, good compatibility with the water–methanol mobile phase and stability of the baseline, as well as the ability to estimate antioxidant activity of plant extracts (a good correlation was established between the total polyphenols determined by manganese(IV)‐based CL method and the antioxidant activity measured by the DPPH and ABTS (2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid)) assays). To the best of our knowledge, this study is the first report on the application of the UHPLC‐PDA‐CL method for the fast separation and sensitive determination of polyphenols, replacing the conventional HPLC.…”