Na Calibration on ICS-3000

[kristopher]

We have a ThermoScientific ICS-3000 dual channel system. We are having difficulty calibrating the Na values. The data for standards at 5 ppm - 100 ppm are great and form a perfect linear calibration; however, data for standards 0.5 ppm - 2.5 ppm are nonsensical. For instance, for the 0.5 ppm standard the software (Chromeleon 7) returns a value of 3.35 ppm; 1.0 ppm returns a value of 3.62 ppm. The other data points are just as erratic. The potassium values are perfect from 0.5 up to 100 ppm. The suppressor was replaced earlier this week but had no impact on the issue.

Based on this information, would you assume the column or detector is bad? Any other suggestions for a possible solution?

[anionman]

What do your blanks look like? Any possible coelutions or contamination? What do the results look like it you force the calibration through zero?