###### Abstract  
The detection of trace aroma compounds in samples with complex matrices such as Chinese liquor (Baijiu) requires a combination of several methods, which makes the analysis process very complicated. Therefore, a headspace solid-phase microextraction (HS-SPME) method coupled with two-dimensional gas chromatography time-of-flight mass spectrometry (GC\(\times\)GC-TOFMS) was developed for the quantitation of a large number of trace compounds in Baijiu. Optimization of extraction conditions via a series of experiments revealed that dilution of the alcohol content of 8 mL of Baijiu to 5%, followed by the addition of 3.0 g of NaCl and subsequent SPME extraction with DVB/CAR/PDMS fiber coating over 45 min at 45 \({}^{\circ}\)C was the most suitable. To check the matrix effects, various model Baijiu matrices were investigated in detail. The quantitative method was established through an optimized model synthetic solution, which can identify 119 aroma compounds (esters, alcohols, fatty acids, aldehydes and ketones, furans, pyrazines, sulfur compounds, phenols, terpenes, and lactones) in the Baijiu sample. The developed procedure provided high recovery (86.79-117.94%), good repeatability (relative standard deviation < 9.93%), high linearity (\(R^{2}\) > 0.99), and lower detection limits than reported methods. The method was successfully applied to study the composition of volatile compounds in different types of Baijiu. This research indicated that the optimized HS-SPME-GC\(\times\)GC-TOFMS method was a valid and accurate procedure for the simultaneous determination of different types of trace compounds in Baijiu. This developed method will allow an improved analysis of other samples with complex matrices. GC\(\times\)GC-TOFMS; trace aroma compounds; quantitative analysis; Chinese liquor (Baijiu) 2021266910202126691021269  
and properties and are present in variable concentrations ranging from less than 1 \(\mu\)g/L to greater than 1 g/L [8; 9]. For some compounds with a very low response on mass spectrometry, if one-dimensional gas chromatography (1-D GC) has been used to quantify them, it is usually necessary to combine a variety of extraction methods, possibly coupled with multiple detectors, to analyze the same sample, which causes the analysis process to be very complicated [7]. For example, the identification of sulfur and nitrogen compounds has great advantages using a flame photometric detector (FPD) and nitrogen phosphorus detector, whereas other compounds are identified using mass spectrometry (MS) [10]. To overcome these drawbacks, comprehensive one-dimensional gas chromatography (2-D GC) was developed that offers substantial advantages over conventional 1-D GC due to its high sensitivity and chromatographic resolution [11]. Two-dimensional GC (GC\(\times\)GC) allows spectra deconvolution of co-eluted peaks, which makes it a useful technique for the separation and identification of trace aroma-active compounds in complex samples, and it can simultaneously identify different classes of compounds [12]. Microextraction sample preparation techniques are currently the methods of choice to perform analytical determination [13]. Headspace solid-phase microextraction (HS-SPME) has been frequently used for analysis of volatiles. However, a drawback of such a generic HS-SPME method is that it is greatly affected by matrix effects and extraction conditions. Because of the competitive adsorption caused by the limited adsorption materials, the analyte peak may be covered [14]. In view of the excellent performance of GC\(\times\)GC in the separation of trace aroma components, whose concentrations are less than 1 mg/L [11], HS-SPME-2-D GC was expected to provide more comprehensive and precise chemical information in distilled alcoholic beverages, but studies using this detection technique mainly focused on qualitative applications or the quantitative detection of certain compounds [11; 12; 15].