RID problem with methanol?

[ACPilot]

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.

[Bruce Hamilton]

My guess would be that the only peak you are seeing is the water peak, and the mixture of your water sample solvent and the methanol is releasing dissolved gases that form a bubble in the detector.

I would lower your RI temp to 35C, ensure you have a little backpressure on the RI ( cheack manual for safe limits, as they usually can't handle much pressure - but short length of 20 thou ID going to higher reservoir might help ), and most importantly - dissolve your sample in the mobile phase - or as near as possible.

Bruce Hamilton