Stir bar sorptive extraction‐liquid desorption applied to the analysis of hop‐derived bitter acids in beer by micellar electrokinetic chromatography

Abstract

Stir bar sorptive extraction-liquid desorption (SBSE-LD) has been applied as an efficient sample preparation method for the analysis of beer bitter acids. Extracts free of almost all interfering compounds were obtained, allowing simultaneous analysis of iso-alpha-acids and reduced iso-alpha-acids. A robust micellar electrokinetic chromatography (MEKC) method was developed that enables fast separation of iso-alpha-acids and reduced iso-alpha-acids. Quantitative data are in good agreement with results obtained by high-performance liquid chromatography (HPLC) using direct beer injection.

Novel stir bar sorptive extraction methods for environmental and biomedical analysis

“…As an alternative to TD, the analyst can use LD. Sampling can also be performed in the headspace of a liquid or a solid sample, the so-called head space sorptive extraction (HSSE) method [45][46][47][48][49][50][51][52], and LD is used [18][19][20][21][22][23][24][25][26][27][28][29][53][54][55]. Approximately 100-200 l of an organic solvent, such as methanol and acetonitrile, is used for the desorption.…”

“…The desorption time is approximately 5-10 min. In the case of LD, the sample is subjected to conventional HPLC [18][19][20][21][22][23][24][25][26][27][28], CE [28,29] or GC with large-volume injection (LVI) [53][54][55].…”

“…The former process has high sensitivity because the entire extract can be analyzed by TD and GC. On the other hand, the latter process can be applied to high performance liquid chromatography (HPLC) [18][19][20][21][22][23][24][25][26][27][28] or capillary electrophoresis (CE) [28,29], and high polarity or thermally labile compounds can be analyzed.…”

Recent advances in micellar electrokinetic chromatography

“…Beer, wine, and spirits were subject to MEKC analysis [71,107,126,166,167]. These and other beverages were analyzed for amino acids [126,166], phenols [71,166], hop acid [107], carbohydrates [167], and even vitamin content [166,168].…”

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

“…Recently, the application of a new solventless extraction method named stir bar sorptive extraction (SBSE) has been described [15]. SBSE combined with liquid desorption (LD) was successfully applied for the analysis of bitter compounds in beer and wort by LC [16], and in beer by micellar electrokinetic chromatography (MEKC) [17].…”