“…Under (nagative) APCI conditions, the fragmentation of precursor ions occurred mainly on the prenyl groups as observed in negative ESI-MS/MS experiment [10] and no abundant product ion corresponding to the loss of acyl group was formed (see Figure 3). Under (positive) APCI conditions, fragmentation of protonated ions could present more characteristic product ions than fragmentation of deprotonated molecular ions (see Figure 4).…”
Section: Lc/apci-ms/ms Detection Of the Six Major Hop Acidsmentioning
confidence: 81%
“…If scanning of each of protonated ion-product ion transition for any bitter acid produced a positive response in the MS/MS chromatogram at the same retention time, the existence of such a targeted compound in the herb was confirmed. Discrimination between the isomers was also performed in considering their retention characteristics and relative amounts as reported [4,10]. Using MS/MS analysis in combination with chromatographic rule, the five minor hop acids, posthumulone, prehumulone, adprehumulone, prelupulone, and "adprelupulone", were determined with retention times at 8.54 min, 14.20 min, 14.98 min, 25.47 min, and 26.67 min, respectively ( Figure 5).…”
Section: Detection Of the Minor Hop Acidsmentioning
confidence: 99%
“…Van der Hoeven et al [10] reported on (negative) LC/ESI/ MS/MS application to the analysis of the six major bitter acids in the extract of hop. In the ESI experiment, MS/MS spectra of -acids exhibit abundant product ions corresponding to loss of a series of alkyl radicals.…”
The applicability of on-line coupling of reversed-phase high-performance liquid chromatography to atmospheric pressure ionization tandem mass spectrometry for the separation and characterization of hop acids mixture from the crude extract of Humulus lupulus was investigated. The solvent system consisting of acetonitrile-aqueous formic acid was used to give proper separation of the six main hop bitter acids within 30 min. Further structural information about the components was acquired by collision-induced dissociation (CID). On the basis of analyses of the fragmentation patterns of the major ␣-and -bitter acids respectively, identification of the minor ones was performed using selected reaction monitoring (SRM) with a group of qualitatively relevant selected precursor-product ion transitions for each bitter acid in a single high performance liquid chromatography (HPLC) run. Using this technique, six minor hop acids, including "adprelupulone" observed for the first time in natural resources, were detected along with the six major acids. This hyphenated techniques provides potency for rapid qualitative determination of analogs and homologs in
“…Under (nagative) APCI conditions, the fragmentation of precursor ions occurred mainly on the prenyl groups as observed in negative ESI-MS/MS experiment [10] and no abundant product ion corresponding to the loss of acyl group was formed (see Figure 3). Under (positive) APCI conditions, fragmentation of protonated ions could present more characteristic product ions than fragmentation of deprotonated molecular ions (see Figure 4).…”
Section: Lc/apci-ms/ms Detection Of the Six Major Hop Acidsmentioning
confidence: 81%
“…If scanning of each of protonated ion-product ion transition for any bitter acid produced a positive response in the MS/MS chromatogram at the same retention time, the existence of such a targeted compound in the herb was confirmed. Discrimination between the isomers was also performed in considering their retention characteristics and relative amounts as reported [4,10]. Using MS/MS analysis in combination with chromatographic rule, the five minor hop acids, posthumulone, prehumulone, adprehumulone, prelupulone, and "adprelupulone", were determined with retention times at 8.54 min, 14.20 min, 14.98 min, 25.47 min, and 26.67 min, respectively ( Figure 5).…”
Section: Detection Of the Minor Hop Acidsmentioning
confidence: 99%
“…Van der Hoeven et al [10] reported on (negative) LC/ESI/ MS/MS application to the analysis of the six major bitter acids in the extract of hop. In the ESI experiment, MS/MS spectra of -acids exhibit abundant product ions corresponding to loss of a series of alkyl radicals.…”
The applicability of on-line coupling of reversed-phase high-performance liquid chromatography to atmospheric pressure ionization tandem mass spectrometry for the separation and characterization of hop acids mixture from the crude extract of Humulus lupulus was investigated. The solvent system consisting of acetonitrile-aqueous formic acid was used to give proper separation of the six main hop bitter acids within 30 min. Further structural information about the components was acquired by collision-induced dissociation (CID). On the basis of analyses of the fragmentation patterns of the major ␣-and -bitter acids respectively, identification of the minor ones was performed using selected reaction monitoring (SRM) with a group of qualitatively relevant selected precursor-product ion transitions for each bitter acid in a single high performance liquid chromatography (HPLC) run. Using this technique, six minor hop acids, including "adprelupulone" observed for the first time in natural resources, were detected along with the six major acids. This hyphenated techniques provides potency for rapid qualitative determination of analogs and homologs in
“…In the past, the application of an acidic mobile phase, gradient elution and UV detection was a common approach for the separation of iso-␣-acids 23 . However, it has been recently shown 10,21 that neutral and alkaline mobile phases, in combination with advanced reversed-phase sorbents, can provide much better selectivity for iso-␣-acids. Baseline separation is attainable especially when isocratic elution is utilized 9 .…”
Section: Introductionmentioning
confidence: 99%
“…Baseline separation is attainable especially when isocratic elution is utilized 9 . The se-lectivity and sensitivity of the measurements has been improved by mass spectrometric (MS) detection employing negative electrospray and atmospheric pressure chemical ionisation 7,10,21 . Finally, the selectivity has been further enhanced by the application of the liquid chromatographynuclear magnetic resonance tandem for the characterization of beer bitter acids 17 .…”
Excellent liquid chromatographic (LC) separation of cis/trans stereoisomers of iso-␣-acids has been achieved with reversedphase sorbent XTerra MS C18. An isocratic alkaline mobile phase, consisting of a mixture of 5 mmol l -1 ammonium acetate (pH 8)-acetonitrile-methanol, 62:21:17 (v/v/v), was used. In the DCHA-Iso international calibration standard trans-isoposthumulone was identified combining photo diode array (PDA) spectra and electrospray high-accuracy mass spectrometric (MS) data. Moreover, the molecular mass of two degradation products resulting from the in-solution storage of the DCHA-Iso standard was determined. The presence of trans and cis isomers of isoposthumulone, isocohumulone, isoadhumulone and iso-n-humulone in beer samples was confirmed. The trans isomers of iso-␣-acids showed characteristic and reproducibly slightly different ultraviolet absorbance spectra with respect to cis isomers.
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