**6. Chemiluminescence singlet oxygen probe**

In the previous discussion, the detection of 1 O2 was based upon either decrease in the absorbance of singlet oxygen probe or enhancement of luminescence signal of fluorescein based probe in presence of 1 O2. In this respect Chemiluminescence is supposed to be one of the most suitable methods for singlet oxygen detection as it does not require any excitation light source, so background fluorescence and interference caused by background light can be eliminated. At the same time the signal to noise ratio can be improved and the possible damage of living cell caused by UV irradiation during fluorescence measurement can be eliminated.
