# Detection of Sub-Aroma Threshold Concentrations of Wine Methoxyprazines by Multidimensional GCMS
## 3 Results and Discussion
### Extraction Optimization
The RI values accurately matched the literature, instilling confidence that the peaks were the desired analytes. While retention time and RIs were used to define the heart-cut and establish the presence of the desired analytes, further separation on the second dimension and the overall mass spectral fragmentation pattern matches using the mass spectrophotometer detector confirmed the separation and identification of the analytes (Figure 3). These methods of identification ensured that the chromatography was isolating the desired peaks for quantification. The addition of heart-cutting for analytical analysis has provided multiple opportunities to further elucidate peaks in complex mixtures such as wine. The ability to send a portion of the sample to a second phase for further separation has allowed for the identification and quantitation of analytes that were previously confounded by co-eluting peaks [19]. [PERSON], [PERSON], and [PERSON] [20] demonstrated the ability of multidimensional analysis in the analysis of galbanum oil. Their study demonstrated the ability to achieve separation of co-eluting compounds by heart-cutting the first phase. Their study further demonstrated the power of this technique by evaluating the time of the heart-cut in order to achieve separation on the second phase. Similarly, the current study used the retention time to establish the appropriate heart-cut regions thereby minimizing the chances of co-eluting peaks on the second phase. Table 2 exhibits the similar and identical retention indices  
Figure 2: First dimension chromatograph of wine captured on FID. Shaded areas are the heart-cut regions sent to the second dimension. of compounds commonly found in wine that are present in the first dimension heart-cut windows and highlights the potential for co-elution when using a single dimension. The retention times of these compounds in the second dimension show the separation achievable and the isolation of the MPs. \begin{table}
\begin{tabular}{c c c c} \hline
**Retention Time** & **Compound** &
\begin{tabular}{c} **Retention Indices** \\ **Literature (1 st dimension)** \\ \end{tabular} & **\% MS Match** \\ \hline
37.41 & (1H)-Pyrrole & 1499 & 95 \\
39.01 & 2,3-Butanediol & 1523 & 98 \\
39.32 & 1-Octen-3-ol & 1423 & 96 \\
40.56 & _cis_-Hept-4-enol & 1502 & 88 \\
40.69 & 6-Hepten-1-ol & n/a & 90 \\
41.40 & Benzaldehyde & 1525 & 98 \\
43.48 & _p_-Cymene & 1426 & 80 \\
43.78 & IPMP & 1423 & \\
43.96 & Siloxane (system peak) & n/a & \\
45.15 & 2-Nonanol & 1521 & 95 \\
45.67 & \(\beta\)- Linalool & 1537 & 97 \\
47.74 & SBMP & 1494 & \\
48.38 & IBMP & 1516 & \\
49.10 & Decanal & 1512 & 94 \\
50.50 & 2-Borrene & 1519 & 89 \\
51.96 & Unknown & \\
53.26 & Vitispirane & 1527 & 94 \\
53.97 & Unknown & \\ \hline \end{tabular}
\end{table} 
Table 2: Compounds detected in the first dimension heart-cut regions of the chromatographs sent to the second dimension. Figure 3: Second dimension selective ion monitoring (SIM) chromatographs of (**A**) deuterated internal standards and (**B**) methoxypyrazines run in SIM mode.