\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sampling Principle** & \begin{tabular}{c} **SFME Fiber,** \\ **Extraction Time** \\ \end{tabular} & **Instrument** & **Analytes** & **LOD (sg m\({}^{-3}\))** & **Ref.** \\ \hline Sampling on XAD-2 resin, accelerated solvent & 100-um PDMS, 40 min & GC-Dual ECD & 22 PCBs & \(2\times 10^{-5}\)–\(4\times 10^{-3}\) & [21] \\ \hline  & & & & Tripepi phosphate & 20 & \\  & & & Tri-n-butyl Phosphate & 40 & \\  & & & Tris(2-chloroethyl) & 70 & \\ Sampling of FM10 on quartz fiber filter, microwave & \begin{tabular}{c} 500-um \\ DVBCar/PDMS, \\ 5 min \\ \end{tabular} & GC-MS/MS & Tris(1-chloro-2-propyl) & 42 & [22] \\  & & & Phosphate & 138 & \\  & & & Tripepi phosphate & 51 & \\  & & & Tricenyl phosphate & 60 & \\ \hline  & & & & BTEX & \\  & & & & Propepiherence & \\  & & & & 1.3-trimeth/benzene & 1–100 & [23] \\  & & & butyl benzene alkanes (C\({}_{5}\), & & \\  & & & C\({}_{10}\)-C\({}_{27}\)) & & \\ \hline Sampling to Tedlar bags, SPME & \begin{tabular}{c} 75-um Car/PDMS, \\ 15 min \\ \end{tabular} & GC-MS & 36 VOCs & 0.01-0.93 & [24] \\ \hline  & & & & & \\ Sampling into 20-ml vials, SPME & \begin{tabular}{c} 100-um PDMS, \\ 3 min \\ \end{tabular} & GC-MS & \
\begin{tabular}{c} 100-um PDMS, \\ Ethylbenzene \\ \end{tabular} & 2 & [25] \\  & & & & \(\circ\)-Xylene & 2 \\ \hline Sampling into 20-ml vials, SPME &
\begin{tabular}{c} 65-um \\ PDMS/DVB, \\ 10 min \\ \end{tabular} & GC-MS & 25 VOCs & 0.01–6.9 & This study \\ \hline  & & & & \\ \hline  & & & & \\ \end{tabular} Notes: n/a—not available: ACM—acconitrile: AED—acconitrile emission detector; BTEX—benzene, toluene, ethylene—c—Carbone; DI—direct immersion; DVB—dvinylbenzene; ECD—electron capture detector; FID—d—d—e ionization detector; GC—gsès chromatography; HS—headspace; LOD—limit of detection; MS—mass spectrometry; MSMS—tandem mass spectrometry; GC—organic—predicronic pesticides PCBs—polychlorinated biphenyls; PDMS—polydimethylsiloxane; SPME—solid-phase microextraction; VOCs—volatile organic compounds.  
\end{table} 
Table 1: _Cont._Despite the high efficiency of the described methods for determination of VOCs in air by SPME (Table 1), there are still challenges limiting their application in routine and research environmental laboratories. Some authors report limitations due to labor-intensive calibration, i.e., requirements for construction of gas generation system with a known concentration of analytes [19; 21; 24; 26]. Most methods require using high-purity gases for preparation of calibration samples, which can be difficult to purchase and prepare. [PERSON] et al. [25] developed a very simple, automated and accurate method for quantification of BTEX using SPME and successfully applied it for the analysis of ambient air in Almaty, Kazakhstan. Sampling was conducted with 20 mL crimp top vials, which were transported to the laboratory, located on the Combi PAL (CTC Analytics, Switzerland) autosampler tray and automatically analyzed using GC-MS. To simplify the method, the authors used standard addition calibration, which did not require any additional equipment and pure gases. The only major drawback of this method was that it allowed quantification of only four analytes [25], while more than 100 organic compounds are present in outdoor air of Almaty [27]. [PERSON] et al. [24] developed the method for determination of 36 VOCs. However, the sampling was done into Tedlar bags, which did not allow automation. In addition, the calibration was carried out with a standard gas mixture of VOCs in pure nitrogen. The objective of this study was to improve the method developed by [PERSON] et al. [25] for quantitation of \(>\)20 VOCs in 20 mL ambient air samples using SPME and GC-MS. During this study, SPME fiber, extraction, desorption and storage times were optimized. The developed method was applied for quantification of chosen VOCs in outdoor air of Almaty, Kazakhstan.