RID problem with methanol?
Posted: Wed Dec 10, 2008 6:51 pm
i've been digging around on this issue for a few days and have come up dry, so i figured i post here to see if anyone has run into this...
i'm not very familiar with RIDs and don't really like them very much having grown up using UV/VIS. however, i'm working on a method for the separation of a C8 chain sulfonate which is normally used as an ion-pairing agent. based on a discustion with a manufacturer of ion-pairing agents, MeOH is used to remove this agent from RP columns. so, that's where i started. after equilibrating the column (Zorbax RX- C8 ) to 100% MeOH, i injected a sample, diluted 1:10 with water. i saw one peak and then the detector maxed out and stayed there for the next 2 hours or so. i thought maybe my sample was too concentrated and diluted it but never injected since i got the same response when i injected a water blank. over the next couple of days, i continued to flush the column with MeOH and try water blanks. the same result. i removed the column, thinking i had altered it somehow and did a run without it. the same result. a single peak and then the detector maxes out.
i'm using a Shimadzu RID-10A with a Shimadzu LC-20 system. i believe all my settings and configurations are correct since i ran through all that with their tech support on the phone. the only thing i can figure is that there is something about 100% MeOH that this detector does not like, but i can't find anything in the literature regarding mobile phase limitations if proper balanceing is used for the reference cell. my column oven is at 35 C and my RID cell temp is 40 C...could that difference cause such a response?
any help would be greatly appreciated.
i'm not very familiar with RIDs and don't really like them very much having grown up using UV/VIS. however, i'm working on a method for the separation of a C8 chain sulfonate which is normally used as an ion-pairing agent. based on a discustion with a manufacturer of ion-pairing agents, MeOH is used to remove this agent from RP columns. so, that's where i started. after equilibrating the column (Zorbax RX- C8 ) to 100% MeOH, i injected a sample, diluted 1:10 with water. i saw one peak and then the detector maxed out and stayed there for the next 2 hours or so. i thought maybe my sample was too concentrated and diluted it but never injected since i got the same response when i injected a water blank. over the next couple of days, i continued to flush the column with MeOH and try water blanks. the same result. i removed the column, thinking i had altered it somehow and did a run without it. the same result. a single peak and then the detector maxes out.
i'm using a Shimadzu RID-10A with a Shimadzu LC-20 system. i believe all my settings and configurations are correct since i ran through all that with their tech support on the phone. the only thing i can figure is that there is something about 100% MeOH that this detector does not like, but i can't find anything in the literature regarding mobile phase limitations if proper balanceing is used for the reference cell. my column oven is at 35 C and my RID cell temp is 40 C...could that difference cause such a response?
any help would be greatly appreciated.