# Organic Materials Used for Giant Buddhas and Wall Paintings in Bamiyan, Afghanistan
## 3 Results
### Identification of Fatty Acids, Protein and Plant Gums by GC-MS
Walnut is common from southeast Europe to Japan, and poppyseed is native to the eastern Mediterranean. However, perilla has been widely used across Asia. All three could be good candidates for drying oils. Other oils (such as linseed oil) may have been possible in caves M, K3, and J(c) due to P/S values below 2. However, P/S values can be affected if oils are used as a mixture [20]. P/S values can also decrease over time, due to evaporation of palmitic acid in the presence of inert pigments [42], so values should always be utilized with some caution. As an example, for drying oils, GC-MS data from BMM035 (Cave N(a)) are shown in Figure 7.  
GC-MS protein analysis of 32 paint samples showed that about 30% of the samples did not contain amino acids (ND), while 30% of the samples contained detectable levels of amino acids from an unknown protein source. The remaining samples matched proteins in the GCI database; for example, BMM054 (Cave M) and KAK10 (Kakrak Cave 44) contained drying oils as well as amino acids that best matched egg based on the correlation coefficients (0.96 and 0.99). The presence of egg and oil illustrate a complex painting technique and could be from different paint layers. BMM045 (Cave G) and BMM169 (Cave J(f)) contained amino acids that best matched casein, or milk protein. While BMM063 (Cave B(d)), FDM 060 (Foladi Cave 6), and KAK 03 (Kakrak 43) best matched animal glue, which was differentiated from casein and egg by the detection of the amino acid hydroxyproline. GC \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sample** & **Cave** & **Description** & **Oil** &
\begin{tabular}{c} **Protein** \\ **(Corr.Coeff.)** \\ \end{tabular} & **Plant Gum** \\ \hline BMM045 & G & yellow, white ground & ND & Casein (0.95) & ND \\ \hline BMM067 & E III & yellow, white ground & ND & Protein & NA \\ \hline BMM082 & F(c) & organic deposit & NA & NA & Tragacanth \\ \hline BMM099 & D & red, white ground & ND & Protein & NA \\ \hline BMM120 & J(d) & blue, pink ground & ND & Protein & ND \\ \hline BMM128 & J(b) & blue/black, white ground & ND & Protein & ND \\ \hline BMM169 & J(f) & red, render & ND & Casein (0.92) & ND \\ \hline BMM184 & N(a) & silver colored surface with blue & NA & NA & Fruit Gum \\ \hline BMM191 & EGB & blue in white, white ground & ND & Protein & ND \\ \hline BMM211-2 & H(b) & red and white ground & ND & Protein & NA \\ \hline BMM212 & H(a) & yellow, white ground & ND & Protein & ND \\ \hline FDM003 & Foladi 5 & red, white ground, size & ND & Egg (0.97) & NA \\ \hline FDM043 & Foladi 3 & red, white ground, two & NA & NA & Plant Gum \\  & renderings & & NA & NA & Tragacanth \\ \hline FDM051 & Foladi 4 & red and germon pink & NA & NA & Tragacanth \\ \hline FDM054 & Foladi 4 & whitish green and red & NA & NA & Tragacanth \\ \hline KAK05 & Kakrak 43 & Yellow ochre color & NA & NA & Fruit Gum \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Summary of GC-MS results for samples without oil. NA = not analyzed, ND = not detected, below detection limit. _Corr.coeff._ = correlation coefficient. MS analysis quantified the so-called \"stable amino acids\" for determination of a correlation coefficient, and these amino acids remain relatively stable over time in the presence of certain pigments, relative to other amino acids that rapidly degrade with oxygen, heat, and humidity. GC-MS plant gum analysis of 58 paint samples revealed that 80% did not contain carbohydrates (ND). However, six samples contained carbohydrates that most closely matched tragacanth gum, and four samples best matched fruit tree gum. The identification of tragacanth gum is based on the detection of fucose, a unique sugar specifically found in tragacanth gum but not present in acacia, Arabic, or fruit tree gums. The identification of plant gums by GC-MS is inherently difficult, most notably in outdoor wall paintings.