Evaluation of Nova 2 Ionised Calcium Instrument Electrodes
Author Information
Author(s): J. A. Fyffe, A. S. Jenkins, H. N. Cohen, Frances J. Dryburgh, Mary D. Gardner
Primary Institution: University Department of Medicine and Department of Biochemistry, Royal Infirmary, Glasgow
Hypothesis
The study aims to evaluate the performance of new electrodes for the Nova 2 ionised calcium analyser compared to the original electrode.
Conclusion
The Nova 2 instrument shows no significant differences in calibration curves and selectivity coefficients among the electrodes, but response times to serum vary.
Supporting Evidence
- Calibration curves from the six electrodes examined were almost parallel.
- All electrodes obeyed the Nernst equation with a change of approximately 58 millivolts for a tenfold change in calcium concentration.
- Response times to serum varied, with four electrodes showing fast responses and two showing slow responses.
- Significant differences in results were noted for two electrodes supplied with the instrument on loan.
Takeaway
The Nova 2 machine can measure calcium levels well, but some of its electrodes take longer to give results when testing blood.
Methodology
Electrodes were compared using two instruments, with simultaneous assays performed in triplicate to evaluate differences.
Potential Biases
There is a risk of bias due to the variability in electrode performance and the lack of detection of faults by the instrument's system.
Limitations
The study encountered issues with quality control serum results that were not detected by the instrument's computer system.
Statistical Information
P-Value
<0.005
Statistical Significance
p<0.005
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