Scientist Solutions - ICPMS High Oxide low Mg U intensity

SMT Posted 3/3/2011 10:01:28 PM	HI, I have been trying to get my daily performance to pass for three days. We have an Elan DRCe. I am getting intensities of 50K for Mg 260K for U but 3.4 for CeO. When I lower the neb gas flow CeO is 3.2 or less but Mg<50K and U<200K. My RF is set to 1500. I have new cones. Sample tubing, waste tubing and all other pump tubing has been changed. Neb gas and auto lens optimizations passed. Please help.
ToxLabRat Posted 3/4/2011 11:59:44 PM	Have you done your XY alignment and optimization process? If not then I would do that. Other than that I would say that if you have done a neb flow optimization, lens voltage optimization and auto lens calibration and you are still having issues with low counts and high oxides, then you probably need to do a Pulse stage optimization, an analog stage optimization and then a dual detector calibration. When is the last time you did the pulse and analog optimization and the DD calibration? If it has been a while then your issue is probably just a result of your detector having been consumed to the point where your pulse stage voltage and analog stage voltage are not optimal anymore. Since the detector is a consumable item it is necessary to optimize the instrument periodically to make sure all settings are aligned with the wearing of that part. Once you do these optimizations and the calibration, you will most likely need to go back and do the auto-lens optimization, autolens calibration, neb gas flow optimization and XY alignment. If that does not do the trick then can you attach a copy of your DP report so that I can see your RSD's, your background, your lens voltage, pulse voltage, analog voltage, etc. settings?
MAT Posted 3/7/2011 3:12:44 PM	Hi, Thanks for your reply. After the optimizations and the dual detector calibration we were able to get Mg>50K, In>259K, U>200K and Ceo=2.9 for our daily performance. However we are trying to use the online setup for the internal standard. When we connect the mixing block the CeO = 3.7. Everything else is fine. Is it ok to have higher oxides with the online setup? Thanks in advance for your help
ToxLabRat Posted 3/7/2011 11:11:50 PM	I have never used online internal standard addition myself but I do know that several people do use that set up and seem to be okay with it. I have never heard of it causing a change in how your Daily Performance numbers look though. Just curious but when you say that you check the DP before putting the block on and it is acceptable but once you put the internal standard introduction block on the oxides go up, does this mean that you are actually running a Daily Performance while you actually have internal standard solution going into the sample introduction system as well? Or are you saying that you just attach the block but do not actually start running internal standard solution through it? If you are attaching the block and have internal standard being pumped into the sample introduction system along with the Daily Performance solution then yes, this will cause your oxide ratio to go up for sure, so if you are doing this then I would stop. Just run your DP like you normally would without the internal standard online addition set up. If you are attaching the block but are not running anything to it, then it is possible that it is adding air to the sample introduction system along with the SmartTune solution and this too, will cause the oxides to go up. Everyone that I know who uses the online internal standard addition does all of their tunning while in the regular set up mode, so maybe you should just go this route.
MAT Posted 3/8/2011 7:13:08 AM	Hi, I have been attaching the online int std setup before doing the DP. However I put the tubing in the 2%HNO3 wash sol during the DP. Thanks
ToxLabRat Posted 3/9/2011 7:14:13 PM	Yes that is your problem. The addition the HNO3/Water solution is thowing off your DP. For starters it is causing the Smart Tune solution to become slightly diluted which is not optimal and secondly the addition of the extra acid is probably causing some residues to leach out of the sample introduction system and as a result this is causing your oxides to be higher. Just run your Daily in the standard set up and then attach your online adding system.
MAT Posted 3/10/2011 6:46:45 AM	Thanks for your help.
EnvSciguy Posted 9/26/2012 2:58:19 PM	I just had a similar problem. As neb gas flow went up U cps actually peaked and began to drop. Mg was low and oxides were high. Adjusting RF did not help. I changed the cones back to the previous ones and the problem went away. The PE tech was using his bare hands on the cones when installing them, not sure if that caused it or not but I plan to send those cones back.