Iraffinity is

Secondary structure was examined using the approach of Hadidi et al. [21 (link)]. The sample (2 mg) and KBr (150 mg) were ground well and pressed into thin slices. The sheets were scanned with a Fourier transform infrared (FTIR) spectrometer (IRAffinity-IS, Shimadzu Ltd., Kyoto, Japan) over the range of 400–4000 cm⁻¹ for 64 scans at a resolution of 4 cm⁻¹. The detailed contents of the secondary structure components were calculated by baseline correction, deconvolution, second derivative processing and Gaussian fitting according to the Peak Fit 4.12 software.

Since the alloy used for body and lid in can packaging are different¹⁴ , this study analyzed both body and lid parts separately to overcome the differences in coating that might be used during the manufacturing process. Body is the part that hold the content within, whereas lid/cover is the part where the can opening is located.
Small portion of each part (approximately 0.5 cm × 0.5 cm) was cut by scissor and polymer type of samples were identified by attenuated total reflectance (ATR) FT-IR (IR Affinity IS, Shimadzu, Japan) for both inside and outside layers. Background spectra was monitored before sample analysis, and isopropyl alcohol (IPA) was used to clean the instrument detector. The FT-IR wavenumber used ranged from 600 to 4000 cm⁻¹, and results spectra were then compared with reference library spectra database to determine the polymer type. The quality threshold for polymer identification was a 75% or greater match to the reference library.