Chemical information from human fluids for therapy monitoring and clinical diagnosis

Several analytical procedures have been developed and optimized to obtain chemical information of diagnostic or therapeutic relevance on non-traditional biological fluids, such as oral fluid, exhaled breath, and spent dialysate. A methodology to determine warfarin in oral fluid by HPLC with fluorimetric detection was developed for the non-invasive monitoring of oral anticoagulant therapy. A high correlation between warfarin concentration and INR was found for patients with salivary pH ≥ 7.2. A thermal desorption, gas chromatography-mass spectrometry methodology was optimized for exhaled breath analysis and applied to the non-invasive monitoring in breath of volatile compounds during oral glucose tolerance test and sevoflurane anaesthetic and its metabolite hexafluoroisopropanol after surgery. A three-compartment pharmacokinetic model was developed and fitted to the post-operative sevoflurane and hexafluoroisopropanol breath data. Photometric and fluorimetric measurements of spent dialysate were proposed for the real time non-invasive monitoring of uremic toxins removal. An excellent correlation was obtained between UV absorption at 292 nm and uric acid concentration in spent dialysate. It was demonstrated that uric acid provides the main contribution to UV absorption at 292 nm. A linear model for the prediction of uric acid concentration in blood from the absorbance of spent dialysate at 292 nm was developed.