Problem with sensitivity of TSQ QuantumUltra and TSQ Vantage

[hoangduc]

We have a TSQ Quantum Ultra system and a TSQ Vantage system. Thermo said that TSQ Vantage is higher sensitivity than TSQ Quantum Ultra. However, when we determine Amlodipine in human plasma by two those system after sample preparation with LLE. The results obtained were contradictory. TSQ Quantum is more twice higher sensitivity than TSQ Vantage. With sample 0.1ng/mL, TSQ Quantum alway have S/N>20, while TSQ Vantage have S/N<10.( LC condition are same). We have tried optimizing for SRM on TSQ Vantage, but not result.(Note: TSQ Vantage is purchased last month, while TSQ Quantum is purchased three years ago)
Who can give some advice?

[rb6banjo]

To me, it's very difficult to say that a system is going to whatever X more sensitive across the board for all molecules. Have you tried to run another molecule that doesn't contain nitrogen atoms or active hydrogens? Something really well behaved - just to get a good comparison of the systems?

[leadazide]

Also beware that because the Vantage is more sensitive than the Ultra you will also see more of the noise/crud in your mobile phase.. So maybe the reason that your signal to noise is lower on Vantage is that your are seeing more noise??

I assume it passed the installation specifications for sensitivity during the installation??

Please contact your local Thermo Scientific service office if your can not get anywhere with this. The Vantage IS a more sensitive instrument but that also carries a price since (as mentioned) is also sees more background in your mobile phase.