Flame photometric determination of salinity in processed foods

The sodium contents determined by flame photometry were used to estimate the salinities of processed foods. The interference effects of potassium and calcium ions on the determination of sodium ion were studied. The threshold interfering patterns of potassium ion and calcium ion for the determination of sodium ion were observed in the model systems. Both of the ions showed enhancement effects on the signals of sodium determination and the increased signal strength depended on the concentration of the ions added above a threshold level. While low level calcium ion hardly interferes with the measurement of sodium ion, the potassium ion exerts marked interfering effects. The salinities based on the chloride contents from Mohr's titration method were obtained for comparison purpose. The salinities of 48 processed food samples determined by the two methods were positively correlated with r2 = 0.9995 and did not show significant difference in the paired t tests (P = 0.2504). Overall, the flame photometric determination of sodium ion provides a rapid, less tedious and more accurate alternative for the quantification of salinity in processed foods.