## 3 Results  
### GC-MS Optimization  
The separation of the analytes of interest was first performed using a standard mixture. The eight fatty acids (including nonadecanoic acid as an internal standard) and four sterols (including cholesterol as internal standard) were separated in less than 30 min as TMS-derivatives (Table 2). The MS parameters were subsequently optimized for selected ion monitoring mode and the ions were used further for the quantification of the compounds (Table 2).  
The instrumental method used was adapted from [PERSON] et al. [52]. Co-elution was observed for TMS derivatives of oleic acid (C18:1) and linolenic acid (C18:3). Chromatographic separation was first attempted for the critical pair C18:1 and C18:3, but no resolution was achieved (Figure 3). The unique ions were identified for the compounds except for the co-eluting peaks. Due to their structural similarity, corresponding fragmentation patterns are also similar. In this case, the 335.2 and 339.3 \(m/z\) fragments were used for linolenic and oleic acid TMS derivatives, respectively, as these are unique ions.  
The standard mixture was also spiked into the synthetic juice and the extraction was performed according to the literature [26]. During this stage, it was observed that the signal from the detector reached saturation at medium concentrations of the lipids. This prompted an evaluation of the dynamic range of the MS in response to the high signal observed and, at the same time, a modification of the original extraction protocol  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Lipid Name** & \begin{tabular}{c} **Lipid Name in** \\ **(Detected as TMS** \\ **Derivative**)** \\ \end{tabular} & \begin{tabular}{c} **Compound** \\ **Abbreviated Form** \\ **(TMS Derivative)** \\ \end{tabular} & \begin{tabular}{c} **Rotention Time** \\ **(Un)** \\ \end{tabular} & \
\begin{tabular}{c} **Quantifier Ion** \\ **(\(m/z\))** \\ \end{tabular} &
\begin{tabular}{c} **Qualifier Ion** \\ **(\(m/z\))** \\ \end{tabular} \\ \hline Myristic acid & C14:0 & 228.37 & 11.28 & 285.2 & 300.3 \\ Palmitoleic acid & C16:1 & 254.41 & 13.72 & 311.1 & 129.0 \\ Palmitic acid & C16:0 & 256.4 & 14.00 & 313.3 & 328.3 \\ Linoleic acid & C18:2 & 280.45 & 16.49 & 73.1 & 337.3 \\ Oleic acid & C18:1 & 282.47 & 16.58 & 73.1 & 339.3 \\ Linolenic acid & C18:3 & 278.43 & 16.61 & 75.1 & 335.2 \\ Stearic acid & C18:0 & 284.48 & 16.97 & 341.3 & 297.3 \\ Nonadecanoic acid (IS) & C19:0 & 298.5 & 18.47 & 117.0 & 370.3 \\ Squalene & C30H50 & 414.71 & 25.98 & 117.0 & 355.3 \\ Cholesterol (IS) & C27H60 & 386.65 & 28.33 & 129.1 & 458.4 \\ Ergosterol & C28H40 & 396.65 & 28.88 & 253.2 & 363.3 \\ \(\beta\)-Sitosterol & C29H50 & 414.71 & 29.61 & 129.1 & 396.4 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Retention times for fatty acids and sterols detected as TMS derivatives. The quantifier and qualifier ions are for the TMS-derivative of each compound. Nonadecanoic acid and cholesterol were used as IS for the fatty acids and sterols, respectively.  
to include a dilution step. The dynamic range was evaluated using peak area and height. The peak area displayed a linear correlation from 750 ppb to 40 mg/L, whereas the peak height displayed linearity from 750 ppb to 50 mg/L for some compounds. These values are important because they need to be taken into consideration for sample preparation optimization and routine analysis.