I measured the wastewater sulfate addition with Thermo Ficher Ion Chromatography (IC) (eluent NaOH of 25 mM w/w), as I used standard solutions of sulfate in the ranges of 50 ppm, 150 ppm, 300 ppm, 450 ppm, and 600 ppm. Although my lab senior said it was too high for the devices, it works and has satisfactory results (see calibration graph in my files). However, in the measurement data of the wastewater, I found several peaks, as I suspected it was a chlorine solution because, as in the manual, the peak of the chlorine anion has a close retention time with the sulfate. So, does anyone know of a suitable syringe filter for removing chlorine for ion chromatography, thus not removing sulfate concentration?
The limit concentration of sulfate in Dionex Ion Chromatography devices varies depending on the method and sample preparation; nevertheless, sensitive values are normally maintained low to avoid column overload. To filter chlorine, a syringe filter with a pore size suited for IC, typically less than 0.45 micrometers, is employed to eliminate particles and prevent column damage.
Hello Dick:
As your senior suggested, the calibration range that you are using is way too high. The fact that "It works and and gives satisfactory results" doesn't mean that it is good for the system, and gives the optimum results. IC systems generally have limits of detection below 0.1 ppm. If you dilute the samples at least by 10X, sensitivity would be ample, and it reduces the peak tailing (improves resolution) and would be more friendly for valves, pump, filters, guard column, etc.. With improved resolution and well separated peaks, you may NOT need a separate filter for removing Cl, which adds further complexity. You may be able to eliminate, those humps that you are seeing on the chromatogram.
Thank you Prof. Rizwana Dilshad and Prof. Nimal De Silva i did what you recommended by filtering the larger particle by using syringe filter by 0.2 micrometer. Furthermore, I also diluted the solution 10 x as the results also more lower than previous ones with no chlorine peak (as no peak rather than sulfate) and also using lower standard calibrations in the ranges of 5, 15, 30, 45, 60 ppm than previous ones.
Dick Dick Maulana Nimal De Silva Thanku very much.Your suggestion is highly appriciable
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