Bilirubin is one of important endogenous fluorophores in human serums.Bilirubin

excited by some wavelengths of light

can emit fluorescence in the range of 500 to 600 nm.There are four forms of bilirubin in human serum;different bilirubin fractions have different physiological meaning and different fluorescent spectra.Investigation of bilirubin fluorescence in human serum will provide some theoretic basis and references for diagnosing some diseases by the autofluorescence of human serum.The fluorescence and absorption spectra of bilirubin solutions and mixed solutions of bilirubin and bovine serum albumin under normal physiological conditions

and the fluorescence spectra of normal human serum samples were measured and analyzed.The experimental results showed that different bilirubin solutions had different fluorescence and absorption spectra;serum albumin has a fluorescent enhancement effect on the fluorescence of bilirubin.BR+BSA mixed solutions aging for two days have different absorption and fluorescence spectra compared with BR+BSA mixed solutions.Moreover

it was educed that the fluorescent peaks located about 525 nm did not mainly derive from the contribution of bilirubin-albumin complex in human serum samples.In other words

the concentration of B

δ

fraction in normal human serum may be very low.Human serum compositions are very complex.There are many endogenous fluorophores that can emit fluorescence in the range of 500 nm to 600 nm.In this experiment

the measured fluorescent peaks of serum samples may come from the contributions of other bilirubin fractions or β-carotene and riboflavin derivatives.The above conclusion was drawn based on some healthy serum samples.But in other cases

such as diseases of jaundice and hepatitis

B

δ

fraction may demonstrate stronger fluorescence.As a result

its fluorescence should be observed.