Analysis of Genuine, Recycled and Artificial Leather by Pyrolysis

Pyrolysis-GC/MS allows for the analysis of organic materials that are too large to be compatible with GC alone. Material is heated in a controlled and reproducible way, facilitating breakdown into volatile compounds that can be studied by GC/MS. Results are polymer specific, making pyrolysis the perfect way to analyze all types of polymers, including natural and synthetic textiles, such as leather and artificial leather.

Genuine leather is created by tanning rawhides from cattle. The main constituent of animal skin is a protein called collagen. The building blocks of protein are amino acids, so the pyrolysis of collagen results in many ring structures such as pyrroles and indoles. Even though genuine leathers are all made from similar raw material, pyrolysis could still unveil subtle difference between different manufacturers by comparing the additives and contaminants. Figure 1 shows a collagen standard and two genuine leather samples pyrolyzed under the same condition. Comparing to the standard, one leather sample uses terephthalate plasticizer, and the other one has a phthalate plasticizer.

Figure 1. Pyrograms of collagen standard (top), genuine leather sample 1 (middle), genuine leather sample 2 (bottom). Sample 1 has terephthalate plasticizer, and sample 2 has a phthalate plasticizer (plasticizers circled in blue).

Figure 2. Recycled leather sample shows Isoprene monomer and dimer.

Figure 3. Two artificial leather samples that are different in color. Top is orange and the bottom is the red.

Recycled leather is generally considered the lowest grade of genuine leather and looks identical to genuine leather. When pyrolyzing recycled leather, a large amount of polyisoprene’s monomer and dimer is observed in Figure 2. This indicates the recycled leather was made from scraps of leather and glued together with a polyisoprene adhesive. Finally, two artificial (faux) leather samples are analyzed. These samples are cut from two wallets that differ only in color (red versus orange). Pyrolysis reveals that they are both acrylic as shown in Figure 3. The red wallet contains butyl methacrylate, and the orange wallet has butyl acrylate. In summary, pyrolysis-GC/MS, carried out in a CDS 6000 Pyroprobe with Autosampler, is proven to be powerful tool in screening different leather products. Contact: Carol Byrd
Tel.: +1 800 541 6593

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