Figure 3.

The scanning spectrophotometric analysis. PBS/EBM-2 (2 mL) in dishes (35-mm) was exposed to air (0 EU), or 1-4 EU (4-16 cigarettes) of CCS as described in the Materials and Methods. The absorption spectrum of the CCS-exposed sample was determined on a scanning spectrophotometer using the wavelengths from 200 to 800 nm. PBS or EGM-2 exposed to 0 EU was used as a blank or a reference for the scanning analysis to eliminate the background absorbance. The representatives of scanning spectrum of 1-4 EU-exposed PBS and 4 EU-exposed EGM-2 are shown, indicating an absorption peak at λ_{290 nm} (Figure 3).