In comparison, the effect of ionization interference on the Mg (279.553 nm) ionic line and Mg (285.213 nm) atomic line was small, but still present. Similar results were obtained for both the ionic and atomic lines of Mg at the different dilution factors, although slight enhancement of the Mg (285.213 nm) line in the more concentrated solution was observed. The addition of cesium appeared to improve accuracy of the result for the Mg (279.553 nm) ionic line, suggesting a small amount of signal suppression due to ionization interference.
Some signal depression was also observed for Cu and Fe, although it was not severe. With the addition of cesium, the determined concentrations were closer to the certified values.
With the addition of cesium, Na still appears to be affected by ionization interference when the levels of EIE are high. This is observed for the Na (330.237 nm) as a higher result was found for the more concentrated blood serum solution. It would therefore be recommended that blood serum be diluted by a least a factor of 100 when repeating the analysis to determine Na.
The determination of sodium was repeated with a 1000-fold dilution of the blood serum. Standards containing 1 and 5 mg/L Na only were prepared and the Na 589.592 nm line was used. No internal standard or ionization buffer was added. Triplicate analyses were done and the average result was 3181 mg/L in the original sample. The analysis was repeated using a standard high flow concentric nebulizer and the average result was 3170 mg/L. Both these results are similar to that obtained for Na (330.237 nm and 589.592 nm) in the 100-fold dilution blood serum sol