Micromethod for determining plasma ammonia nitrogen with use of an ion-selective electrode

A micromethod for measuring the ammonia nitrogen content of plasma by use of an ion-selective electrode is evaluated and described. The effect of storing plasma for 24, 48, and 72 h at -70 degrees C was evaluated. Values for newborns and fasting adults were 880 micrograms/L (SD, 210 micrograms/L) and 620 micrograms/L (SD, 170 micrograms/L), respectively.