Urea Determination in Human Sera With an Ammonium Ion Selective Electrode Made With Solid Inner Electric Contact and Immobilised Urease

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.

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Sodium ion binding in human serum.

Clinical Chemistry ◽

10.1093/clinchem/28.3.449 ◽

1982 ◽

Vol 28 (3) ◽

pp. 449-452 ◽

Cited By ~ 8

Author(s):

T R Kissel ◽

J R Sandifer ◽

N Zumbulyadis

Keyword(s):

Standard Addition ◽

Sodium Ion ◽

Ion Selective Electrode ◽

Ion Selective Electrodes ◽

Ion Binding ◽

Selective Electrode ◽

Titration Method ◽

Low Sodium ◽

Human Sera ◽

Sodium Binding

Abstract The amount of sodium ion binding in human sera and in dialyzed human sera was estimated from standard-addition titrations with an ion-selective electrode and from measurements of 23Na nuclear magnetic resonance (NMR) linewidth. For the untreated sera, maximum binding was 1% (1.4 mmol/L) as indicated by NMR; virtually no binding was found via the titration method. For dialyzed sera with low-sodium, normal-protein content, NMR indicated that sodium binding was less than 1.3% (0.14 mmol/L). The same dialyzed fluid analyzed with ion-selective electrodes shows no sodium binding, within the limits of experimental error (+/- 4%). Sodium ion binding to serum protein thus contributes only minimally to differences in sodium measurements observed between the direct (undiluted) ion-selective electrode and flame-photometric methods.

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Simultaneous Analysis of Ammonium and Nitrate Ions Levels with Potentiometric Multi-commutation Flow System Method

Jurnal ILMU DASAR ◽

10.19184/jid.v22i1.17767 ◽

2021 ◽

Vol 22 (1) ◽

pp. 69

Author(s):

Fajrin Nurul Hikmah ◽

Tri Mulyono ◽

Zulfikar Zulfikar

Keyword(s):

Detection Limit ◽

Flow System ◽

Ion Selective Electrode ◽

Ammonium Ion ◽

Selective Electrode ◽

Nitrate Ion ◽

Nitrate Ions ◽

Limit Value ◽

System Method ◽

Recovery Percentage

This study aims to develop a multi-commutation flow system method for simultaneous determination of ammonium ion and nitrate ion using two detectors, namely ammonium ion selective electrode and nitrate ion selective electrode. The multi-commutation flow system method uses two three way selenoide valves to adjust the sample flow and ISA solution. The selenoid valve alternately flows the sample and ISA solution to the ion selective electrode. Flow control by three way selenoid valves is controlled by LabView which is programmed in the computer. The computer is connected with Arduino and a relay that functions as an on-off switch on the three way valve selenoid. This method is then applied to measure the levels of ammonium ions and nitrate ions in well water samples. The performance of the multi-commutation flow system determined includes linearity, limit detection, sensitivity, repeatability, and recovery test. Ammonium analysis results show good performance with several criteria. Ammonium linearity value is 0,9991, ammonium detection limit value is 2,23 × 10-5 M, sensitivity of ion selective electrode ammonium is 45,39 mV per decade, the repeability value is less than 2% and the recovery percentage of ammonium is 115%. While the results of the nitrate analysis showed a linearity value of 0,9937, a nitrate detection limit value of 1,31 × 10-5 M, sensitivity of the ion selective electrode nitrate of -110,58 mV per decade, a repeatability value of less than 2% and a recovery percentage of 87% nitrate. Keywords: Flow Analysis, multi-commutation, ammonium, nitrat, simultaneous.

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