Figure 6: Near-infrared absorption spectra of ACV ointments, observed to 4000-10000 cm−1. (a) 2nd differential near-infrared absorption spectra of ACV ointments, observed to 5700-5950 cm−1. (b) 2nd differential near-infrared absorption spectra of ACV ointments, observed to 5100-5300 cm−1.