Abstract:
A descriptive, cross sectional study conducted in Sudan, Khartoum State
during the period of May to August 2007. Analytical and statistical methods were
applied to compare results of Eppendrof flame photometer, IL-543 digital flame
photometer and ion selective electrode, for measurement of sodium and
potassium and assess the difference that can be found, also to check the accuracy
and precision of the instruments.
Blood samples from a total of 55 apparently healthy adult males (volunteers)
were taken randomly, and specimens (plasma) were analyzed for sodium and
potassium concentrations by three different instruments. The results were
statistically analyzed.
Results showed that the mean concentrations of sodium were 138±3.7 for the
IL-543 digital flame photometer, 140±2.9 for the ion selective electrode and
136±3.6 for the Eppendrof flame photometer. And the mean concentrations of
potassium were 3.7±0.3 for the IL-543 digital flame photometer, 3.9±0.4 for the
ion selective electrode and 3.7±0.3 for the Eppendrof flame photometer.
In considering the IL-543 as the reference method, the data obtained by
ANOVA test showed that, there was a significant difference between IL- 543 and
ion selective electrode for the mean concentrations of plasma sodium where the p
value was 0.008, as well as, the significant difference between the IL-543 and
Eppendrof flame photometer where the p value was 0.001. Also there was a high
significant difference between the ISE and Eppendrof were p value was 0.00.
Also ANOVA test showed that, there was a significant difference between
IL-543 and ISE for the mean concentrations of plasma potassium, where the p
value was 0.01, as well as, the highly significant difference between ISE and
Eppendrof flame photometer, where the p value was 0.001. The test also showed
that there was no significant difference between the IL-543 and Eppendrof flame
photometer for plasma potassium where p value was 1.000.
This study concluded that there was a difference in results obtained by the
three different instruments, which can be attributed to variation in plasma water,
residual liquid junctions, binding of ions to protein or any other ligand or
interference from other ions when using ISE, on the other hand source of error in
using Eppendrof flame photometer due to fluctuations in the light sources.
Further studies should be conducted for more accuracy and precision of any new
introduced instrument.
