API 2000 sensitivity of nitrosamines

[meillid]

Hi, I am trying to validate a nitrosamine method on my API2000, whatever how I tune the instrument against my compound, it couldn't detect as low as 1ng/ml as the method specified. I got a very tiny singal for 10ng/ml of the pure solution nitrosamine. Anybody experienced tell me do I need to further spend time to tune the instrument or not? what is best that API2000 can achieve? What can I do to improve the sensitivity? Thanks a million!

[Ary]

From memory, I think you are fighting a losing battle with a 2000. I could be wrong but if so hopefully someone else will let you know. From the figures you've quoted though I'd say you have got everything on the button, its just the 2000 is not able to do any better for this analysis.

[meillid]

Ary, thank you very much for reply.the known method was developed from a Micromass Quattro Ultima---triple quadrouple MS, does it more sensitive than 2000? Thanks.

[LarryHouse]

I'm not sure what your method is, but I also had sensitivity issues with a rapamycin assay that I was developing for my API2000. what I ended up doing was use analyst quantitative optimization to tune the lenses, then I did a FIA manual optimization by teeing in the compound with the syringe pump, and watched the MRM transition as I tweaked the gases, and temperature. It worked very well for me. I hope I was able to explain it clearly enough for ya!

[Ary]

Emily Lee

Again from memory the Ultima is significantly more sensitive than the 2000. Obviously it varies from compound to compound but would as a general rule expect the Ultima to be at least 10x more sensitive than the 2000.

[meillid]

Thanks, ary and larryhouse. I decided to stop after I reach the LOD of 6ng/ml. I believe that is the best. I really appreciate the information that you provided to my question.