## 3 Results and Discussion
### Metal Content Assessment  
The metal content was assessed merely to gain an initial understanding of the presence of heavy metals in the textiles. While this aspect is not the central focus of the work, it provides additional insights that could be of interest. The concentration (in ppm) of heavy metals in the samples, together with the Oeko Tex Standard limits, is reported in Table 3. The limits of detection (LOD) and quantification (LOQ) and the coefficients of determination of the calibration curves are reported in Table 3 in Appendix A. \begin{table}
\begin{tabular}{c c c c c c c} \hline  & \({}^{\text{53}}\)**Cr** & \({}^{\text{58}}\)**Ni** & \({}^{\text{60}}\)**Cu** & \({}^{\text{95}}\)**Mo** & \({}^{\text{119}}\)**Cd** & \({}^{\text{200}}\)**Hg** & \({}^{\text{208}}\)**Pb** \\ \hline canov\_blu & 0.120 \(\pm\) 0.019 & 0.464 \(\pm\) 0.009 & 0.308 \(\pm\) 0.038 & \(<\)LOD & 0.0088 \(\pm\) 0.002 & \(<\)LOD & 0.160 \(\pm\) 0.009 \\ canov\_ross & 0.118 \(\pm\) 0.005 & 0.358 \(\pm\) 0.015 & 2.48 \(\pm\) 0.296 & \(<\)LOD & 0.0049 \(\pm\) 0.0001 & \(<\)LOD & 0.0785 \(\pm\) 0.010 \\ tess\_98 & 0.537 \(\pm\) 0.068 & 4.65 \(\pm\) 0.206 & 130 \(\pm\) 4.47 & 0.244 \(\pm\) 0.022 & 0.0171 \(\pm\) 0.010 & 0.0106 \(\pm\) 0.007 & 0.234 \(\pm\) 0.125 \\ tess\_99 & 0.408 \(\pm\) 0.144 & 3.28 \(\pm\) 1.57 & 4.40 \(\pm\) 1.21 & 0.014 \(\pm\) 0.022 & 0.0232 \(\pm\) 0.018 & 0.0158 \(\pm\) 0.005 As shown in the table, all the analyzed samples comply with legal limits, except for the samples labeled \"tess_98\" and \"tess_99\", both of which are 100% cotton. In particular, sample \"tess_98\" has a significantly higher concentration of copper compared to the other metals present in the sample. The copper concentration in the sample is 130 ppm, more than three times the legal limit set by the Oeko-Tex Standard 100, which specifies a copper concentration range of 1-40 ppm for fabrics in direct contact with the skin. The sample \"tess_99\" also shows a copper concentration higher than that of the other metals, though not as high as \"tess_98\", but still exceeding the legal limit (Cu concentration of 44 ppm compared to the 40 ppm safety limit). The reason for this can be associated with the fact that copper can be used as a component in some dyes used in textiles; moreover, it is often involved in the dyeing process as a catalyst or stabilizer to promote the color fixation reaction on the fabric. Additionally, copper can be used in dyeing processes as a mordant or fixer for prints to improve the color stability and durability of fabrics. Therefore, we can hypothesize that the higher copper concentration in both \"tess_98\" and \"tess_99\", as printed fabrics, may be due to a print fixation treatment. Besides copper, the two samples \"tess_98\" and \"tess_99\" also present higher concentration levels of chromium, although still below the safety limit for skin contact exposure. Chromium VI (hexavalent) is used in some textile and tanning processes in the footwear industry; it is highly toxic, even at low concentrations, to many aquatic organisms. It is commonly used as a mordant in textile dyes to enhance color resistance and durability. Since 1 May 2015, the EU has banned the sale of shoes and leather goods exceeding 2 mg/kg of this metal. Additionally, cadmium, mercury, and lead have been classified as \"priority hazardous substances\" under EU water regulations and are subject to strict restrictions. The sample \"tess_98\" presents, in addition to copper, a slightly higher concentration of nickel compared to the Oeko-Tex Standard 100 safety limits. The nickel concentration is 4.65 ppm, while the safe exposure range for nickel in fabrics in contact with the skin is between 1 and 4 ppm. Nickel is found in pigments, dyes, metal alloys, and metal coatings. The most common effect of nickel exposure is an allergic reaction and sensitization due to prolonged direct skin contact with nickel.