# Hunting Molecules in Complex Matrices with SPME Arrows: A Review
## 5 SPME Arrow Applications  
### Environmental Analysis  
SPME technology has applicability for environmental pollutants in air, water, soil and sediment, and it can be used in the field or in the laboratory for sample preparation [17; 18]. An advantage of the SPME Arrow is the larger phase volume that allows for the collection of a higher amount of the target compounds, so reporting requirements for environmental data users can be met. One drawback of the traditional SPME fibers for headspace analysis is that the amount of analyte enriched on the coating is not sufficient to meet the reporting limits established by environmental agencies. The SPME Arrow design allows for four-to-five times higher analytical responses of compounds than a traditional SPME fiber [29]. For instance, the work performed by [PERSON] et al. presented a comparison of several techniques for determining volatile organic compounds including: purge and trap (P and T), ITEX, sample loop, traditional SPME fiber, gas-tight syringe, and SPME Arrow. As can be seen in Table 3, the detection limits for the SPME Arrow are in the same range as P and T and ITEX techniques, which are representative of exhaustive extraction techniques. However, the automation of workflow for the SPME Arrow is not only simpler than for P and T but also compatible with direct immersion experiments, which are not doable by ITEX [14]. In another study, [PERSON] and collaborators developed a method capable of detecting picogram-per-liter (0.05 and 0.6 ng L\({}^{-1}\)) levels of water taste and odor compounds (i.e., isopropyl-3-methoxyprazine, 2-isobutyl-3-methoxyprazine, geosmin, 2-methylisoborneol, 2,4,6-trichloroanisole, 2,4,6-bromoanisole, and beta-ionone) in water samples [18]. As a matter of fact, this fully automated workflow was more sensitive than existing methodologies (see Table 4). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Method Name** & **Analylytes** & **Sample Volume (mL)** &
\begin{tabular}{c} **Calibration Range** \\ **(ng L\({}^{-1}\))** \\ \end{tabular} & **LOD (ng L\({}^{-1}\))** & **RSD (\%)** & **Ref.** \\ \hline Purge and trap & IPMP, IBMP, GSM, & 20 & 10–200 & 0.2–2 & \textless{}8 & [42] \\  & MIB, TCA & & & & & \\ Solvent & GSM & 5 & 5-900 & 0.8 & \textless{}5 & [43] \\  & SBSE & GSM, MIB, TCA & 60 & 0.1–100 & 0.02–0.16 & \textless{}3.7 & [44] \\  & DLLME & GSM, MIB & 12 & 10–1000 & 2 and 9 & \textless{}11 & [45] \\  & IPMP, GSM, MIB, & 40 & 5–100 & 0.2–0.5 & \textless{}7 & [46] \\  & TC, BA & & & & & \\ PAL SPME Arrow & IPMP, IBMP, GSM, & 10 & 1 (2.6)–1000 (2600) & 0.05–0.6 & \textless{}11 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of the developed PAL SPME Arrow with similar methods for determination of taste and odor compounds in water samples. Table reprinted with permission of [PERSON] from Reference [18], 2019. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Method Name**} & \multicolumn{4}{c}{**Sources with Reported Detection Limits in \(\mathbf{ng\,L^{-1}}\)**} & \\ \cline{2-11}  & **This Work** & [30] & [31] & [32] & [33] & [34] & [35] & [36] & [37] & [38] & [39] & [40] \\ \hline \hline Syringe & 25-143 & / & / & 1–2 \(\times 10^{3}\) & / & / & 25–53 & / & 66–570 \(\times\) & / & / & / \\ Loop & 25-168 & / & / & / & / & / & / & / & / & 8–20 \(\times\) 10\({}^{3}\) & 5–20 \(\times\) 10\({}^{3}\) \\ SPME & 0.5–79.6 & 5–00 & 2.0–550 & 80–600 & / & / & / & 8–012 & / & / & 2–26 \(\times\) 10\({}^{3}\) & / \\ PAL SPME & 0.7–4.9 & / & / & / & / & / & / & / & / & / & / \\ Arrow & 0.6–9.6 & / & / & / & / & 10–10 & / & / & 7–149 \(\times\) & 0.5–91 & / \\ Trap & 0.9–9.1 & / & / & / & 28–799 & 1.0–70 & / & / & / & / & / \\ Simple matrix & Lab Water & Spirit & Wastewater & Water Lab water & Under Water & Underium & Split & Water & Beer & Wet ice \\ MDL method & \({}^{a}\) & \({}^{b}\) & NS & b & \({}^{a}\) & a & NS & NS & \({}^{c}\) & \({}^{d}\) & \({}^{e}\) & \({}^{b}\) \\ \hline \hline \end{tabular}
\end{table}