# Detection of Sub-Aroma Threshold Concentrations of Wine Methoxyprazines by Multidimensional GCMS
## 3 Results and Discussion
### Wine Analysis  
The method was applied to three research wines: Sauvignon blanc, Rose, and Pinot noir. Each wine was analyzed for its concentrations of MPs (Table 5). Each wine was a control experimental wine, therefore each wine varietal result is the average of three individual terms. While the Sauvignon blanc and Pinot noir were harvested immediately prior to commercial harvest the Rose was harvested at a controlled soluble solids of 18 \({}^{\circ}\)Brix. The IPMP was detected in all wines, except Pinot noir, but only quantifiable in the Sauvignon blanc at 0.259 \(\pm\) 0.031 ng/L. However, the Rose when calculated had a mean value just below the LOQ of 0.248 \(\pm\) 0.026 ng/L with several of the analyses being in the quantifiable range. The SMBP and IBMP were quantified in all three wines. The detected levels of the individual MPs were below the accepted values for aroma thresholds except for IBMP in the Rose wine. The observed value was greater than the 1 ng/L perception threshold typically associated with a white wine, but lower than the 10 ng/L values associated with a red wine [23,24]. The increased value is most likely associated with the early harvest of this grape for involvement in the trial. There are several factors that can alter the MPs concentration in wine. Conditions that promote a decrease in the MPs concentration are: grape ripeness, ripening temperature, bunch exposure, and viticultural practices, to name just a few [24, 25, 26]. The obtained values of IPMP and IBMP were within the ranges observed by [PERSON] et al. [6] using a stir bar sorptive extraction in white, Rose, and red wines. Interestingly, while the method employed by [PERSON] was able to detect the compounds in pg/L levels, \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Wine**} & \multicolumn{2}{c}{**IPMP**} & \multicolumn{3}{c}{**SBMP**} & \multicolumn{3}{c}{**IBMP**} \\ \cline{2-9}  & \begin{tabular}{c} **Spike** \\ **Concen-** \\ **tration** \\ **(ng/L)** \\ \end{tabular} & \begin{tabular}{c} **\% Re-** \\ **covery** \\ \end{tabular} & \begin{tabular}{c} **Spike** \\ **Concen-** \\ **tration** \\ **(ng/L)** \\ \end{tabular} & \begin{tabular}{c} **\% Re-** \\ **covery** \\ \end{tabular} & \begin{tabular}{c} **\% Cv** \\ **(ng/L)** \\ \end{tabular} & \begin{tabular}{c} **Spike** \\ **Concen-** \\ **(ng/L)** \\ \end{tabular} & \begin{tabular}{c} **\% Re-** \\ **covery** \\ \end{tabular} & \
\begin{tabular}{c} **\% Cv** \\ **(n/g/L)** \\ \end{tabular} &
\begin{tabular}{c} **\% Cv** \\ **(n/g/L)** \\ \end{tabular} \\ \hline Sauvignon & 0.66 & 95.1 & 5.47 & 0.66 & 97.1 & 2.95 & 2.73 & 106.3 & 2.30 \\ Sauvignon & 2.26 & 102.0 & 1.41 & 2.21 & 101.2 & 1.15 & 9.14 & 101.8 & 0.57 \\ blanc & 0.66 & 98.0 & 2.27 & 0.66 & 97.0 & 2.81 & 2.73 & 100.3 & 3.04 \\ Model wine & 3.32 & 100.8 & 1.34 & 3.33 & 101.3 & 2.62 & 13.72 & 100.1 & 2.82 \\ (high-range) & 0.66 & 97.7 & 3.43 & 0.66 & 94.9 & 5.21 & 2.73 & 99.6 & 6.57 \\ Pinot noir & 0.66 & 100.5 & 0.30 & 0.66 & 94.3 & 4.68 & 2.73 & 95.7 & 3.88 \\ \hline \hline IBMP—2–Isobutyl-3-methoxypyrazine, d\({}_{3}\)-IBMP—deuterated 2-Isobutyl-3-methoxypyrazine, IPMP—2-Isopropyl-3-methoxypyrazine, & & & & & & \\ d\({}_{3}\)-IPMP—deuterated 2-Isopropyl-3-methoxypyrazine, & & & & & & & \\ \end{tabular}
\end{table} 
Table 4: Percent recovery and coefficient of variation (%CV) of methoxypyrazines spiked in three distinct wine styles and a model wine solution.