title: The influence of indoxyl sulfate and ammonium on the autofluorescence of human urine.
abstract: Despite biological variability the spectral characteristics of undiluted human urine show relatively low autofluorescence at short UV (250-300nm) excitation. However with dilution the fluorescence intensity remarkably increases. This paper examines the mechanisms behind this effect, by using excitation-emission matrices. Corrections for the inner filter effect were made for improved understanding of the spectral patterns. We focused on three major fluorophores (tryptophan, indoxyl sulfate and 5-hydroxyindole-3-acetate) that are excited at these wavelengths, and whose content in urine is strongly linked with various health conditions. Their fluorescence was studied both individually and in combinations. We also examined the effect of ammonium on the fluorescence of these major fluorophores individually and in combinations. Through these studies we have identified the leading effects that reduce the UV fluorescence, namely higher concentration of indoxyl sulfate producing the inner filter effect and concentration quenching and quenching of fluorophores by ammonium. This result will assist in broader utilisation of UV fluorescence in medical diagnostics.
authors.affiliation: Department of Physics and Engineering, Macquarie University, Sydney 2109, NSW, Australia.
authors.forename: Sandeep Menon
authors.initials: SM
authors.lastname: Perinchery
authors.forename: Unnikrishnan
authors.initials: U
authors.lastname: Kuzhiumparambil
authors.forename: Subramanyam
authors.initials: S
authors.lastname: Vemulpad
authors.forename: Ewa M
authors.initials: EM
authors.lastname: Goldys
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D005453:Fluorescence; D006801:Humans; D007200:Indican / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D014556:Urine; D055815:Young Adult
chemical_list: D000644:Quaternary Ammonium Compounds; D007200:Indican