## 2 Materials and Methods
### Sample Selection
Analysis of Volatiles Released by Films Using Contact Solid-Phase Micro-Extraction (SPME) Coupled with Gas Chromatography/Mass Spectrometry (GC/MS)  
A total number of 25 films, selected from those reported above as having different degradation and conservation status, based on the carrier material cellulose acetate were analyzed under controlled climatic storage conditions, using contact solid-phase microextraction (SPME) (Merck KGaA, Darmstadt, Germany) coupled with gas chromatography/mass spectrometry (GC/MS) (HP 5890, Hewlet Packard inc., Palo Alto, CA, USA; MSD 5972, Agilent Santa Clara, CA, USA; Column: ZB-5 HT, Zebron, Phenomex, Torrance, CA, USA). The SPME techniques allows the sampling, extraction, concentration, and sample introduction into the column to be performed as a single step, without the need for organic solvent for sample extraction or complex procedures to calculate sample dilution and loss. This comparatively simple and efficient method, which has been widely used in different fields of analytical chemistry such as environmental and food analysis, is based on the extraction of solutes and volatiles from a sample matrix employing a highly absorptive polymeric layer coated onto a solid fused silica fiber. After a fixed exposure time of the fiber to the sample, equilibrium is reached between analytes in the matrix and analytes absorbed on the fiber and the extracted mass are, from this moment on, maximized and constant. The concentration of extracted analytes is thus proportional to their concentration in the sample. The SPME fiber with the absorbed analytes is directly inserted into the injection system of the gas chromatograph (GC), where the analytes desorb into the gas mobile phase (helium) which also acts as a carrier. In conjunction with the insertion of the fiber in the injector, the GC analysis is started. The described method has been routinely used for gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) analyses and successfully applied to a wide variety of compounds, especially for the extraction of volatile and semi-volatile organic compounds from industrial, environmental, biological and food samples [19], as well as for analyses of volatile compounds in the context of cultural heritage objects [20; 21]. Since the method is non-destructive, it can be applied to valuable original films, without damage or need of destructive sampling. Adapting the application of the method described in [PERSON] et al. [20], in this particular case, the atmosphere was analyzed \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Owner/Code** & **Film Name** & **A-D Strip Level** &
\begin{tabular}{c} **Acetic Acid** \\ **Concentration (ppm)** \\ \end{tabular} \\ \hline \hline
**Osterreichische Akademie Der Wissenschaften** & & & \\ \hline
88 & Der Bär & 1 & 1–2 \\ \hline
90 & Die Spielwütigen Dose 1 & 3 & \textgreater{}20 \\ \hline
94 gr Rolle & & 0 & \textless{}0.5 \\ \hline
96 & Der Monotype Satz & 0 & \textless{}0.5 \\ \hline Carsta 62 & & 0 & \textless{}0.5 \\ \hline Carsta 63 & & 1 & 1–2 \\ \hline Carsta 64 & & 0 & \textless{}0.5 \\ \hline Carsta 65 & & 0.5 & 0.5–1 \\ \hline Film 99 & Memento & 3 & \textgreater{}20 \\ \hline SCS 00060-1 & FBI sucht [PERSON] & 1 & 1–2 \\ \hline SCS 00060-4 & FBI sucht [PERSON] & 3 & \textgreater{}20 \\ \hline SCS 00060-5 & D FBI sucht [PERSON] Pos. Kopie Nr. 12 & 1.5 & 3–5 \\ \hline SCS 00061-3 & Lemmy Caution schlägt zu & 3 & \textgreater{}20 \\ \hline SCS\_00057A & Der 20. Juli 1944 & 3 & \textgreater{}20 \\ \hline SCS\_00058A & Nordlicht & 2 & 6–8 \\ \hline SCS\_00059 & Deutsche Wochenschau & 3 & \textgreater{}20 \\ SCS\_00060-3 & FBI sucht [PERSON] & 2–2.5 & 10–15 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: \(Cont.\)directly in the original film cans using divinylbenzol/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fibers, which were chosen to obtain general analysis results including polar analytes.