Bile sensing with optical fibres

Bile determination is very useful to diagnose many gastric pathologies. Actually the measurement is performed with Bilitec 2000, an optical fibre sensor, based on the absorption by bilirubin. Nevertheless erroneous evaluations can occur due to different configurations which the bilirubin molecule can adopt. The optical behaviour of human samples of pure bile and bile + gastric juice has been examined by an optical fibre spectrophotometer and two Bilitec 2000 units properly modified. The analysis on pH dependance evidenced the presence of different calibration curves at different pH values, while Bilitec units showed that 420 nm could be a more appropriate wavelength for bilirubin detection.