Introduction. It was shown earlier that the use of Fast Protein Liquid Chromatography (FPLC) and low-cost deep-UV-LED-based optical chromatographic sensors with PD-10 desalting columns can facilitate monitoring of patients on peritoneal dialysis (PD). Previously, we established that the first peak in FPLC chromatograms is responsible for proteins and could be used for the assessment of peritoneal protein loss in patients with PD, while the origin and clinical significance of the other two peaks still remain unclear.
Methods. Optical absorption and fluorescence spectroscopy in the UV and visible regions 240…720 nm was used for the analysis of PD effluent fractions obtained with a chromatographic sensor with photometric detection at 280 nm; chromatograms of five samples were processed.
Results. The absorption and fluorescence spectra of the first fraction demonstrated peaks at 280 nm and 330 nm, respectively, which are characteristic of proteins. The absorption spectrum of the third fraction has maxima characteristics of creatinine and uric acid, while the second fraction surprisingly revealed no distinctive absorption bands. When it exited at 280 nm, the second fraction showed a single fluorescence maximum at 300 nm, while for the third fraction, there are maxima at 300, 300, 375 nm—the latter is characteristic of indoxyl sulfate.
For all three fractions, two fluorescence emission peaks are observed at longer excitation wavelengths, 300–320 nm, with the Stokes shifts of about 50 and 150 nm. The ratios of their amplitudes depend on the fraction. These peaks could probably be responsible for ascorbic acid, uridine, 3-indole acetic acid, and other metabolites.
Conclusions. It was demonstrated that deep-UV-LED-based affordable chromatographic sensors could provide sufficiently more information about PD effluents than just protein concentration, including the content of clinically significant metabolites, e.g., indoxyl sulfate. Moreover, the introduction of fluorescence detection could significantly improve the capabilities of such devices.
