# Identification by GC-MS Analysis of Organics in Manufactured Articles through a D-Optimal Design
## 3 Results
### GC-MS Analysis
#### 3.2.1 Samples A to F
Figures S2 and S3 in the Supplementary Materials represent the chromatograms of samples B and B1, respectively, carried out with the parameters of Experiments 8 (sonication extraction with dichloromethane and time of analysis of 24 min) and 2 (Soxhlet extraction with dichloromethane and time of analysis of 24 min), respectively. Compounds that were present in sample B were like sample A: phenolic and bisphenolic molecules. This is a confirmation that they are both phenolic resins. Moreover, sample B contained some siloxane molecules that are characteristic of its modification. Not many siloxanes had a good match within the library, but in the chromatograms, there were many peaks with the characteristic mass spectrum of these compounds. This extraction method enabled us to recognize a specific modification of a resin and therefore to distinguish between two different phenolic resins. This aspect is of fundamental importance in the quality control sector of a product. Moreover, many molecules, including hexamethylenetetramine, were still present in sample B1, which may be an indicator of less curing than in sample A1. Sample B was not analyzed after conditioning, since A2, with the same heat treatment, did not show the presence of compounds. The chromatogram of sample C with the parameters of Experiment 2 (Soxhlet extraction with dichloromethane and time of analysis of 24 min) is reported in the Supplementary Materials (Figure S4). Although it is a phenolic resin, sample C is completely different from previous ones. Here, indeed, there were several phenyl compounds, but also many molecules, alcohols, and esters, with long alkylic chains absent in samples A and B. The latter may come from cardanol oil; moreover, oleic acid ((Z)-octadec-9-enoic acid) is a characteristic compound of oily substances. Sample D has the same composition as sample C; they are made by the same company, but they are produced with different starting materials. Compared to sample C, in D, different furan molecules were found; this may be an indicator of a lower degree of curing as the extraction collects the non-cross-linked portion. Moreover, in samples C and D, di-p-tolyl sulfone (1-methyl-4-(4-methylphenyl)sulfonylbenzene) was identified that was not in the other cardanol resins studied: this compound is characteristic of this company and can be seen as a marker of their production process. The cardanol resin of Sample E used boric acid as a curing agent; there were no molecules with boron, but there were many with furan groups. As in sample D, this may be an indication of low curing. In sample F, characteristic compounds of cardanol resin, such as carboxylic acids attributable to cardanol oil, were identified. In addition, there were many molecules with nitrogen, both nitriles and amides, that may come from reactions between compounds present in cardanol oil and hexamethylenetetramine, which is used in the preparation of this material. Also in this case, the presence of some specific molecules is an indication of an incomplete curing process. Comparing samples from C to F, we can recognize different chemicals present in samples and thus attribute them to a specific production process and even to a specific supplier. Both of these aspects are fundamental for a good quality control of an industrial product. Having analyzed and characterized the raw materials, it is now interesting to see if these are recognizable within the manufactured article.