2019 Volume 40 Issue 1 Pages 9-18
Glucuronyl- and sulpho-conjugates of intestinal putrefactive compounds (IPC) are considered kidney disease-associated toxic agents. Recently, several simultaneous methods of detection by liquid chromatography tandem mass spectrometry (LCMS/MS) of the conjugated forms of glucuronyl- and sulpho-conjugates in blood serum were reported. To analyze these conjugated forms in urine, we modified and validated the LC-MS/MS detection methods. The range of the calibration curves were determined using phenyl glucuronide (PhG; 1.56-25.0 μM), indoxyl glucuronide (IndG; 1.25-20.0 μM), p-cresyl glucuronide (PCG; 0.625-10.0 μM), phenyl sulfate (PhS; 3.13-50.0 μM), indoxyl sulfate (IndS; 7.81-250 μM) and p-cresyl sulfate (PCS; 1.56-25.0 μM). Urine was diluted 2-4 fold to determine PhG, IndG and PCG concentrations, and 4-16 fold to determine PhS, IndS and PCS concentrations. We validated the newly-modified detection methods by a recovery test, and intra-day and inter-day repeatability. We analyzed six clinical urine samples, PCS and IndS, major toxic agents, which were mostly detected. Creatinine-corrected values of PCS and IndS were high in six conjugates. In summary, in the present work, the concentrations of six urinary conjugated forms of IPC were successfully measured by LC-MS/MS.