Figure 13: FTIR ATR spectra of attached HRP protein on LDPE. The spectra of LDPE is subtracted. Three main lines Amide A, I and II of protein are clear visible. The centre peak is CO2 gas in FTIR spectrometer. The regions of polyethylene lines (2980–2820 cm−1 and 1480–1450 cm−1) are noisy after subtraction.