Separation of uremic toxins from urine with resorcinarene-based ion chromatography columns

People with chronic kidney disease suffer from uremic toxins which accumulate in their bodies. Detection and quantification of uremic toxins help diagnose kidney problems and start patient care. The aim of this research was to seek a new method to assist this diagnosis by trace level detection and separation of guanidine containing uremic toxins in water and urine. To detect and quantify the uremic toxins, new stationary phases for ion chromatography (IC) columns based on glutamic acid functionalized resorcinarenes bound to divinylbenzene macroporous resin were prepared. The new column packing material afforded separation of the five compounds: guanidinoacetic acid, guanidine, methylguanidine, creatinine, and guanidinobenzoic acid in 30 min. Peak resolutions ranged from 7.6 to 1.3. Gradient elutions at ambient temperature with methanesulfonic acid (MSA) solution as eluent resulted in detection levels in water from 10 to 47 ppb and in synthetic urine from 28 to 180 ppb. Limits of quantification for the analytes using pulsed amperometric detection were 30-160 ppb in water and 93-590 ppb in urine. Trace levels of creatinine (1 ppm) were detected in the urine of a healthy individual using the columns.