Analysis of iso-α-acids and reduced iso-α-acids in beer by direct injection and liquid chromatography with ultraviolet absorbance detection or with mass spectrometry

Vanhoenacker, Gerd; Keukeleire, Denis De; Sandra, Patrick

doi:10.1016/j.chroma.2004.02.038

Cited by 50 publications

(36 citation statements)

References 15 publications

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“…The HPLC analysis was performed according to Vanhoenacker et al (2004) on an apparatus consisting of a degasser mod. G1322A, a binary pump mod.…”

Section: Detection Of α-Acids Iso-α-acids and Reduced Iso-α-acidsmentioning

confidence: 99%

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Physico-Chemical Indices, Iso-alpha-Acid, Phenolic Contents and Antioxidant Activity of Commercial Beers

Baiano

Terracone

2013

JFR

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The effects of brewing style on physicochemical indices, iso--acids and antioxidant contents of commercial beers were investigated. A great variability was highlighted for all the considered parameters (sugar and alcohol contents, density, pH, titratable acidity, iso--acids, phenolic content, antioxidant activity). The beers having the highest iso--acids contents were Guinness Special Export Stout (which also showed the highest phenolic content), Chimay Pères Trappistes Triple, and Greene King IPA whereas the lowest values were detected in Cuveè De Ranke, Heineken Premium Quality Lager, and Riedenburger Brauhaus gluten free. The latter also had the lowest phenolic concentration. The antioxidant activity values strictly correlated with the total phenolic content but not with the iso-α-acid amount. The Principal Component Analysis failed in distinguishing beers based on their declared type/styles. This was a predictable result since the beer styles don't represent a compositional classification but they are rather used to indicate commercial types.

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“…The HPLC analysis was performed according to Vanhoenacker et al (2004) on an apparatus consisting of a degasser mod. G1322A, a binary pump mod.…”

Section: Detection Of α-Acids Iso-α-acids and Reduced Iso-α-acidsmentioning

confidence: 99%

“…Tetrahydroiso--acids also exist as cis and trans isomeric pairs, totalling six stereoisomers. Reduction of iso--acids to dihydroiso--acids introduces an additional chiral centre, leading to twelve stereomeric members of dihydroiso--acids (Vanhoenacker, De Keukeleire, & Sandra, 2004).…”

mentioning

confidence: 99%

Physico-Chemical Indices, Iso-alpha-Acid, Phenolic Contents and Antioxidant Activity of Commercial Beers

Baiano

Terracone

2013

JFR

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“…Their structures have been verified by elemental analysis 23,24 , 1 H and 13 C NMR 17,23,24 , chiroptical methods 23,24 , GC-MS 16,24 , MS 9,11,21 , UV 4,11,23 and HPLC 2,5,8,9,21,23 . The preparation of pure iso-␣-acid from hop-derived extracts has also been described by Hughes 12 .…”

Section: Introductionmentioning

confidence: 99%

“…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 .…”

Section: Introductionmentioning

confidence: 99%

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Liquid Chromatography-Diode Array and Electrospray High-Accuracy Mass Spectrometry of Iso-α-Acids in DCHA-Iso Standard and Beer

Hofta

Dostálek

Sýkora

2007

Journal of the Institute of Brewing

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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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Trace bensulfuron‐methyl analysis in tap water, soil, and soybean samples by a combination of molecularly imprinted stir bar sorption extraction and HPLC‐UV

Chen

Yang

Zhou

2011

J of Applied Polymer Sci

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A molecularly imprinted stir bar was prepared using bensulfuron-methyl as the template molecule and methacrylic acid as the functional monomer. The imprinted and nonimprinted stir bars were characterized by scanning electron microscopy, nitrogen sorption porosimetry, thermogravimetric analysis, and differential scanning calorimetry. Extraction time, desorption time and pH value affecting extraction efficiency of the stir bar have been evaluated to achieve the selectively direct preconcentration of the template from aqueous samples. Competitive sorption experiments demonstrated that the imprinted stir bar gave high selectivity and imprinted effect on the template bensulfuron-methyl compared to the nonimprinted stir bar. Based on S/N of 3, LOD was 0.83 nM. The method showed good recoveries and precision, 92.4% (RSD 1.5%, n ¼ 3) for tap water spiked with 126 ng (100 mL sample), 84.6% (RSD 2.2%, n ¼ 3) for soil spiked with 210 ng (100 g sample) and 73.7% (RSD 2.1%, n ¼ 3) for soybean spiked with 250 ng (5 g sample), suggesting that the imprinted stir bar sorption extraction can be successfully applied to the preconcentration of bensulfuronmethyl in real samples.

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Analysis of iso-α-acids and reduced iso-α-acids in beer by direct injection and liquid chromatography with ultraviolet absorbance detection or with mass spectrometry

Cited by 50 publications

References 15 publications

Physico-Chemical Indices, Iso-alpha-Acid, Phenolic Contents and Antioxidant Activity of Commercial Beers

Physico-Chemical Indices, Iso-alpha-Acid, Phenolic Contents and Antioxidant Activity of Commercial Beers

Liquid Chromatography-Diode Array and Electrospray High-Accuracy Mass Spectrometry of Iso-α-Acids in DCHA-Iso Standard and Beer

Trace bensulfuron‐methyl analysis in tap water, soil, and soybean samples by a combination of molecularly imprinted stir bar sorption extraction and HPLC‐UV

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