Looking for advice on our Thermo Dionex Ultimate 3000
Posted: Tue Jan 08, 2019 2:04 pm
Summary: We purchased an LCMS system second hand and have spent almost 1 year trying to get it working for our applications. I am looking for impartial advice in order to get a fully working system.
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I own a small research laboratory in the Netherlands. We offer custom synthesis services and therefore need to be able to qualitatively analyse reaction mixtures as well as verifying the purity of finished products. We also receive some external samples from customers that require analysis in order to identify the product and confirm purity (they usually provide us with the target molecule structure so we know what we're looking for).
We have a Dionex UltitMate 3000 LC System with DAD and Thermo TSQ Access LC/MS/MS with HESI II Source. We set the system up ourselves and have the LC component working very nicely but the MS component is nothing but trouble - the masses are always way off. After spending months chasing Thermo (their support is terrible) we managed to get an engineer out and he changed some settings and determined that one of the quadrupoles was faulty (Q1 I think). He said that it is fine though and will only affect the masses of higher molecular weight compounds (>900 Da). That is OK for us since we are working mostly with small molecule drugs right now.
However, the issue isn't fixed. The masses are still way off (even for small molecules) and there is often a lot of background noise in the spectra. The only way to get accurate masses in the spectra is to inject a reference sample directly into the MS and add this data to the tune file. Of course, this isn't possible when you're trying to identify novel compounds that you don't have a reference for.
Another problem we've noticed is that the sheath gas never goes above 15 units (it should be 35 as default). The nitrogen generator is new and is able to deliver 30 L/min at 100 psi. Thermo thinks it might be a valve in the MS. Could this be contributing to our problems?
Due to the ongoing problems I have been contacting other suppliers of MS systems to see if we can swap out our TSQ for something that actually works. Agilent seems to think that the TSQ isn't suitable for our needs. They say this is a 'quantitative MS' and what we need is a 'qualitative MS'. They are suggesting a Q-TOF.
Of course, Agilent (and any other supplier) wants the sale so I cannot trust their recommendations. This is why I am posting on this forum, to get impartial advice on this issue from the very knowledgeable people here. As you can probably tell, I am not an analytical chemist. I have an organic chemistry background but I have not spent much time with the hardware side of analytical chemistry.
Any help would be much appreciated! Sorry for the book.
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I own a small research laboratory in the Netherlands. We offer custom synthesis services and therefore need to be able to qualitatively analyse reaction mixtures as well as verifying the purity of finished products. We also receive some external samples from customers that require analysis in order to identify the product and confirm purity (they usually provide us with the target molecule structure so we know what we're looking for).
We have a Dionex UltitMate 3000 LC System with DAD and Thermo TSQ Access LC/MS/MS with HESI II Source. We set the system up ourselves and have the LC component working very nicely but the MS component is nothing but trouble - the masses are always way off. After spending months chasing Thermo (their support is terrible) we managed to get an engineer out and he changed some settings and determined that one of the quadrupoles was faulty (Q1 I think). He said that it is fine though and will only affect the masses of higher molecular weight compounds (>900 Da). That is OK for us since we are working mostly with small molecule drugs right now.
However, the issue isn't fixed. The masses are still way off (even for small molecules) and there is often a lot of background noise in the spectra. The only way to get accurate masses in the spectra is to inject a reference sample directly into the MS and add this data to the tune file. Of course, this isn't possible when you're trying to identify novel compounds that you don't have a reference for.
Another problem we've noticed is that the sheath gas never goes above 15 units (it should be 35 as default). The nitrogen generator is new and is able to deliver 30 L/min at 100 psi. Thermo thinks it might be a valve in the MS. Could this be contributing to our problems?
Due to the ongoing problems I have been contacting other suppliers of MS systems to see if we can swap out our TSQ for something that actually works. Agilent seems to think that the TSQ isn't suitable for our needs. They say this is a 'quantitative MS' and what we need is a 'qualitative MS'. They are suggesting a Q-TOF.
Of course, Agilent (and any other supplier) wants the sale so I cannot trust their recommendations. This is why I am posting on this forum, to get impartial advice on this issue from the very knowledgeable people here. As you can probably tell, I am not an analytical chemist. I have an organic chemistry background but I have not spent much time with the hardware side of analytical chemistry.
Any help would be much appreciated! Sorry for the book.