## 3 Results and Discussion
### GC Analysis
#### 3.2.1 P&T GC-MS
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**TR (min)** & **CAS N\({}^{*}\)** & **Compound** & \(m/z\) & **CM1** & **CM2** & **CM3** \\ \hline
6.38 & 123-72-8 & Butanal & \(44,72\) & X & X & X \\
6.57 & 78-93-3 & 2-butanone & \(43,72\) & & & X \\
7.69 & 78-83-1 & Isobutanol & \(43,74\) & X & & \\
8.66 & 71-36-3 & 1-butanol \({}^{*}\) & \(41,56\) & X & X & X \\
9.31 & 80-62-6 & Methyl methacrylate & \(41,69,100\) & & X & \\
10.92 & 108-88-3 & Toluene \({}^{*}\) & \(65,91\) & X & X & X \\
12.24 & 66-25-1 & Hexanal \({}^{*}\) & \(43,56\) & & & X \\
13.59 & 100-41-4 & Ethyl benzene & \(91,106\) & & X & X \\
13.85 & & Xylene structure & \(91,106\) & X & X & X \\
14.50 & & Xylene structure & \(91,106\) & X & X & X \\
15.28 & 111-76-2 & 2-butoxyethanol \({}^{*}\) & \(57,87\) & X & X & X \\
15.42 & 108-94-1 & Cyclohexanone & \(55,69,98\) & X & & \\
16.45 & & Trimethylbenzene & \(105,120\) & & & \\
17.18 & & Trimethylbenzene & \(77,105,120\) & X & X & X \\
17.61 & 124-13-0 & Octanal & \(41,56,69\) & & & X \\
17.99 & & Trimethylbenzene & \(59,105,120\) & & & X \\
18.01 & 13429-07-7 & 1-(2-methoxypropyl)-2-propanol & \(59,105,120\) & & & \\
18.28 & 104-76-7 & 2-ethyl-1-hexanol & \(57,70,83\) & & & \\
18.57 & 105-05-5 & 1,4-diethylbenzene & \(105,119,134\) & & & \\
18.77 & 108-95-2 & Phenol \({}^{*}\) & \(66,94\) & & X & \\
19.30 & 19.30 & Unknown (benzene structure) & \(119,134\) & & & X \\
19.32 & 112-07-2 & 2-butoxyethyl acetate & \(43,57,87\) & X & X & \\
19.79 & 98-86-2 & Acetophenone & \(70,105,120\) & & X & \\
20.00 & 124-19-6 & Nonanal \({}^{*}\) & \(28,32,57,70\) & X & X & X \\
20.26 & Unknown (benzene structure) & \(119,134\) & & X & \\
20.82 & 1119-40-0 & Dimethyl glutamate & \(59,100,129\) & X & & \\
22.20 & 112-31-2 & Decanal & \(28,41,57,70\) & X & X & X \\
23.44 & 95-16-9 & Benzothiazole & \(69,108,135\) & & & \\
24.79 & & Unknown (benzene structure) & \(119,131,147\) & & & \\
25.00 & Unknown (naphthalene structure) & \(117,131,160\) & & & \\ \hline \hline \end{tabular} \({}^{*}\)confirmed with standards.  
\end{table} 
Table 1: Volatile compounds detected in the non-targeted analysis by P&T GC-MS. Methyl methacrylate, found in CM2, is a monomer used to produce acrylic resins and is listed in the positive list for monomers used for plastics coming into contact with foodstuffs with a group specific migration limit (SML) of 6 mg/kg [21]. This makes sense since a styrene/acrylic copolymer was identified in the outer side by FTIR-ATR. As regards the monomers used in the manufacturing process, the former Scientific Committee on Food evaluated methyl methacrylate and butyl methacrylate, allocating a group TDI (tolerable daily intake) of 0.1 mg/kg body weight per day (expressed as methacrylic acid) [22]. Methyl methacrylate is also used as an alternative cross-linking agent in styrene [23]. The NIAS 2-ethyl-1-hexanol, found also in this sample, could be an impurity from the monomer 2-ethylhexylacrylate which is used in the production of acrylic adhesives [24] and was also described as a product formed by thermal decomposition or hydrolysis of plasticizers such as bis(2-ethylhexyl) phthalate (DEHP) or bis(2-ethylhexyl) adipate (DEHA) [25]. In sample CM2, more compounds were detected, such as 1-(2-methoxypropoxy)-2-propanol, which are used as a solvent in the manufacture of water-based coatings and as a coalescing agent for water-based paints and inks [26]: phenol, which suggests that the main coating could undergo cross-linking reaction with a phenolic resin [27]; acetophenone, which could be produced during the heat degradation of PET [28], identified by FTIR-ATR for this sample; and benzothiazole, a photolytic decomposition product of an ultraviolet (UV) photoinitiator, which can be considered as an NIAS [29]. These photoinitiators are used to initiate polymerization during ink curing. For illustration, Figure 3 shows a GC chromatogram of the coated tinplate sheet CM2 with the identification of some peaks.