A comparison of three electrodes for the measurement of pH in small volumes
| Autor: | A.J. Preston, A. Smit, P. Cleaton-Jones, M.A. Pollard |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Hydrogen ion
Materials science Analytical chemistry Dental Plaque Buffers Reference electrode law.invention Quinhydrone electrode law Calibration Humans Child General Dentistry Electrodes Reproducibility Analysis of Variance Reproducibility of Results Oxides Hydrogen-Ion Concentration Glass electrode Electrode Linear Models Glass ISFET Microelectrodes Ion-Selective Electrodes |
| Zdroj: | Caries research. 31(1) |
| ISSN: | 0008-6568 |
| Popis: | An ion-sensitive field effect transistor (ISFET, Sentron, Sentron, Inc.) electrode was compared with a glass combination micro-electrode (MI-410, Micro-electrodes, Inc.) and a solid-state metal wire oxide pH sensor (Beetrode, World Precision Instruments, Inc.) with a liquid junction reference electrode (MERE1, World Precision Instruments, Inc.). The electrodes were assessed for linearity, reproducibility, accuracy, drift from the initial calibration between pH 4 and pH 7 and the time taken to record a stable reading. The ISFET was used to determine the pH in dental plaque samples (1 mg suspended in 20 microliters). The pH values correlated with the hydrogen ion concentration for all the electrodes (r = 0.98). The MI-410 fractured before this evaluation was completed. Coefficients of variation were 0.65% (pH 4) and 0.08% (pH 7) for the ISFET and 4.69% (pH 4) and 3.46% (pH 7) for the Beetrode. Both electrodes gave readings that differed significantly from the initial calibration, but the drift was greater for the Beetrode (F = 7.93; p = 0.0005) than the ISFET (F = 1.89; p = 0.1519). However, this drift was smaller than the change in pH as measured in dental plaque samples. The Beetrode gave a stable reading after 3.39 +/- 0.83 s and the ISFET after 2.2 +/- 0.76 s, while the MI-410 required at least 20 s. The ISFET type electrode is suitable for use in small volumes such as plaque suspensions, is easier to operate and yields results closer to the initial calibration than the Beetrode and is more robust than the MI-410 and the Beetrode. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|