New methods for the determination of L-asparagine and arginine are described. Solutions containing L-asparagine were pumped through an asparaginase tube, which catalyzed the hydrolysis of L-asparagine to L-aspartic acid and ammonium ion. For L-arginine determination, solutions containing L-arginine were pumped through an arginase–urease tube. This dual enzyme tube catalyzed the conversion of L-arginine to L-ornithine, carbon dioxide, and ammonium ion. The ammonium ion concentrations in the effluent of the enzyme tubes were determined quantitatively by an ammonium-ion-selective electrode. The potentiometric response of the electrode was directly proportional to the logarithm of the concentration of L-asparagine and L-arginine in the range of 0.1–50 mM. An equation relating the electrode response and the substrate concentration is derived.
Overcoming of One More Pitfall in Boundary Element Calculations with Computer Simulations of Ion-Selective Electrode Response
