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. 2022 Feb 15;27(4):1318.
doi: 10.3390/molecules27041318.

Volatile Analysis of Wuliangye Baijiu by LiChrolut EN SPE Fractionation Coupled with Comprehensive GC×GC-TOFMS

Jia Zheng  1 , Zhanglan He  1 , Kangzhuo Yang  1 , Zhipeng Liu  1 , Dong Zhao  1 , Michael C Qian  2
Affiliations

Volatile Analysis of Wuliangye Baijiu by LiChrolut EN SPE Fractionation Coupled with Comprehensive GC×GC-TOFMS

Jia Zheng et al. Molecules. .

Abstract

Wuliangye baijiu is one of the most famous Chinese liquors with a protected geographical indication. This study used LiChrolut® EN-based solid-phase extraction (SPE) and fractionation combined with comprehensive two-dimensional chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS) to unveil its volatile composition. The volatiles were isolated with LiChrolut® EN-based SPE and traditional liquid-liquid extraction (LLE). The neutral/basic fractions from LLE and the SPE were fractionated on a LiChrolut® EN SPE column and analyzed by comprehensive GC×GC-TOFMS. Compared with LLE, more esters and alcohols were detected in the SPE-based extraction. The SPE fractionation and GC×GC-TOFMS analysis resulted in the identification of about 500 volatile compounds in more than 3000 peaks of the Wuliangye baijiu. The approach simplifies the complex baijiu composition into functional group-based fractions for reliable identification and analysis. This study provided a confidence volatile identification approach for Chinese baijiu based on the SPE fractionation GC×GC-TOFMS.

Keywords: GC×GC-TOFMS; LiChrolut® EN SPE; Wuliangye; baijiu; volatile fractionation.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Authentic chemical standards for testing the applicability of GC×GC-TOFMS system. (A). Esters; (B). Mixture of acetals, pyrazines, and furans; (C). Mixture of alcohols, aldehydes, and acids.
Figure 2
Figure 2
(A) Four peaks shown in the conventional chromatogram. (B) Five peaks clearly separated in the contour chromatogram. 1. 1,1-diethoxy-3-methylbutane (m/z 47), 2. ethyl 3-methylbutanoate (m/z 88), 3. butyl acetate (m/z 43), 4. hexanal (m/z 57), and 5. 2-methylpropanol (m/z 74).
Figure 3
Figure 3
(A) GC×GC total ion chromatogram contour plots of fractions from Fraction 1 to Fraction 10 from SPE extract. First dimension time range: 300–2700 s, and second dimension time range: 0–4 s. (B) Distribution of (I) ethyl hexanoate, (II) furfural, (III) 1,1-diethoxy-3-methylbutane, and (IV) β-damascenone in fractionation. (C). Main acetals in fraction 2 of Wuliangye baijiu. 1. 1,1-diethoxyethane, 2. ethyl acetate, 3. 1,1-diethoxybutane, 4. 1,1-diethoxy-3-methylbutane, 5. 1,1-diethoxypentane.
Figure 3
Figure 3
(A) GC×GC total ion chromatogram contour plots of fractions from Fraction 1 to Fraction 10 from SPE extract. First dimension time range: 300–2700 s, and second dimension time range: 0–4 s. (B) Distribution of (I) ethyl hexanoate, (II) furfural, (III) 1,1-diethoxy-3-methylbutane, and (IV) β-damascenone in fractionation. (C). Main acetals in fraction 2 of Wuliangye baijiu. 1. 1,1-diethoxyethane, 2. ethyl acetate, 3. 1,1-diethoxybutane, 4. 1,1-diethoxy-3-methylbutane, 5. 1,1-diethoxypentane.
Figure 4
Figure 4
Distribution of each class of volatile compounds in LLE-based fractionation (LF) and SPE-based fractionation (SF).
See this image and copyright information in PMC

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