All measurements were performed using a commercially vailable kit (Cayman Chemicals, MI, USA). 100 μl
sodium dodecyl sulfate (SDS) solution was added to 100 μl plasma sample or standard solution in 5 ml tubes
and vortexed. 4 ml color reagent was added to each tube. Tubes were placed in water bath at 100 ฐC for 1h. Immediately after boiling, tubes were incubated on ice for 10 min to stop reaction. Tubes were centrifuged at 1600 g
and 4 ฐC for 10 min. 150 μl of each sample were added to wells of a 96-well plate. Samples were analyzed within
30 min using a microplate reader at 530 nm.