ABTS and 2.20-azobis (2-amidinopropane) dihydrochloride
(AAPH) were dissolved in phosphate-buffered saline (PBS, containing
150 mM NaCl) in a 1:1 ratio and the mixture was incubated
in a 37 C water bath to an absorbance at 734 nm. An aliquot of each
sample was mixed with ABTS solution.