Chromatography Forum

Hello all,

My lab is currently weighing options for upgrading our ICP-MS now that USP <233> is becoming effective. We currently have an ELAN 6100 (no DRC), but since we test a pretty large variety of pharmaceuticals, nutraceuticals, etc., I've made the recommendation that we move towards an ICP-MS with some sort of interference removal technology so that we aren't handicapped by interferences due to sample matrices.

My question is, is there an advantage to having a collision cell over a reaction cell? I'm currently trying to put a proposal together and would like to factor in whether one is a bigger advantage over the other, or possibly even get an ICP-MS with both (e.g. Nexion 300+). We're a very small business and we usually buy generations old used equipment, so buying the shiny, brand-spanking new, top of the line is out of the question.

I was actually leaning towards an ELAN 9000 DRC, but was interested to see if anyone felt going with a NexION 200/300/etc. was worth the extra investment.

Thanks for any help!

Vince

Reaction cell and Collision cell are basically the same thing. Both use an RF field and Hydrogen or Helium gas to remove interference. The Agilent models use one cell and either of the gasses one at a time to remove different interfering elements.

We just sold a Nexion we had been using for environmental samples. Our samples were just too dirty for it. It seemed more suited for research than high productivity. I don't remember which model it was, we inherited it in the purchase of another lab. Mostly I am familiar with Agilent ICP-MS and they do run the dirty samples well, but no matter what you are running they all will have some trouble staying in calibration when the crud passes through them. The worst problem we have is with internal standard counts drifting high or low out of range, then returning back to normal after a few clean samples pass through if you are lucky. Clean samples with only isobaric interferences are handled well, but crud that collects on the cones or in the nebulizer are what will cause most of the failures.

Thanks for the reply! Yes, our current ICP-MS (ELAN 6100) has some issues with dirty samples as well from time to time. We have to keep re-running in order to meet drift suitability checks on some of the dirtier samples.

I thought the DRC used reactive gases (e.g. ammonia); whereas, a simple collision cell used an inert gas like Helium to just "collide".

I forgot where I read it, but someone had mentioned that collision cell has better application for certain elements than a reaction cell.

In any event, I think the biggest issues I want to correct are chloride interferences affecting accurate detection of arsenic and vanadium. Also, some help with silicon analysis would be beneficial.

Thanks again,

Vince

Thank you so much


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Reaction cell and Collision cell are basically the same thing. Both use an RF field and Hydrogen or Helium gas to remove interference. The Agilent models use one cell and either of the gasses one at a time to remove different interfering elements.

We just sold a Nexion we had been using for environmental samples. Our samples were just too dirty for it. It seemed more suited for research than high productivity. I don't remember which model it was, we inherited it in the purchase of another lab. Mostly I am familiar with Agilent ICP-MS and they do run the dirty samples well, but no matter what you are running they all will have some trouble staying in calibration when the crud passes through them. The worst problem we have is with internal standard counts drifting high or low out of range, then returning back to normal after a few clean samples pass through if you are lucky. Clean samples with only isobaric interferences are handled well, but crud that collects on the cones or in the nebulizer are what will cause most of the failures.

Hello James,

Again thanks for the reply. I wanted to pick your brain a bit. It looks like you have a system suitability requirement for internal standard counts. Is this pretty typical? We don't currently employ that as a requirement and I do see the internal standard counts drop a fair amount once we hit the sample analysis part of the run.

I thought the internal standard was mainly used to handle that kind of drift in the signal from measurement to measurement?

Thanks again,

Vince

We are using EPA methods 200.8 and 6020 for environmental samples and those methods have stated recovery limits for internals standards based on the internal standard counts of the initial calibration blank. 60%-125% is one of the methods limits. The limits are set because even though the internal standard will help compensate for drift due to sample matrix, since each element responds a little differently, the internal standard can not completely compensate for large drifts accurately.

I believe we use Helium mode for V and Hydrogen mode for As to help eliminate the interference from Cl. Both have advantages and disadvantages, the gas modes will have much lower sensitivity overall than the standard no gas mode because of the change in ultimate analyzer pressure reducing sensitivity.