unexplained drop off in anion concentration of references
Posted: Tue Nov 15, 2011 11:28 am
Our Dionex ICS2000 is used for analysis for chloride, nitrate, nitrite, fluoride, bromide and sulphate in groundwaters. We filter to 0.45 microns. Recently we have seen a drop off in our calibration standard results even when we have ascertained that the standards were made up correctly. We use 2 reference solutions along with our samples and these refs have suddenly come out low, about half the expected concentration for each of the 3 minor anoions (bromide, nitrite and fluoride). Randomly, the first run of the refs was low, the second run of refs (same solutions just poured out again) was spot on. Anyone have any idea what is going on with the instrument?
The sample transfer tube was recently replaced due to a blockage, as we often analyse waters containing ammonia or related ions and because we receive so little sample we cannot filter, so were wondering if these waters could be contaminating the column. Also, and it may be a separate issue but certainly won't be helping, we have a recurring problem with the membrane attached to the effluent cartridge (we use KCl). The level in the cartridge increases rather than decreases and it shouldn't do this. We had an engineer sort it ages ago and a fresh cartridge was fitted but now its happening again. We are having a lot of downtime with this instrument and can't help thinking there is something fundamentally wrong that we are unaware of and can't fix. Does it sound as if the system has been knackered by runnning unfiltered ammonia waters through it? We have cleaned the column recently too. We are at a loss! Any suggestions would be greatly appreciated, thank you. Sarah.
The sample transfer tube was recently replaced due to a blockage, as we often analyse waters containing ammonia or related ions and because we receive so little sample we cannot filter, so were wondering if these waters could be contaminating the column. Also, and it may be a separate issue but certainly won't be helping, we have a recurring problem with the membrane attached to the effluent cartridge (we use KCl). The level in the cartridge increases rather than decreases and it shouldn't do this. We had an engineer sort it ages ago and a fresh cartridge was fitted but now its happening again. We are having a lot of downtime with this instrument and can't help thinking there is something fundamentally wrong that we are unaware of and can't fix. Does it sound as if the system has been knackered by runnning unfiltered ammonia waters through it? We have cleaned the column recently too. We are at a loss! Any suggestions would be greatly appreciated, thank you. Sarah.