FIGURE 7.
(a) Measurements of ammonia in urine headspace collected with the CODA and an ISE electrode for 3.5 hrs after the subject drank a protein shake. Both devices show ammonia concentration levels dropped 0.5 hr after drinking the protein shake but continued to rise until the experiment ended. It is worth noticing 17ppm = 1 mM NH4+ (b) The accuracy of the CODA was determined by systematically comparing its measurement to an ammonia ISE electrode (reference method). The measurement of the CODA was converted to NH4+ level in liquid solution for clinical practical use by Medical Professionals. (c) Analytical performance of CODA: Receiver operating characteristic (ROC), using ISE method to determine True diagnostic ability as its discrimination threshold varied from 5, 10, 15, 20, 30, 40 mM NH4+ (read total ammonia levels).