[IchTuan.NGUYEN]

Hi all, i have 1 question in urgent , i tried to determination of Piracetam on MS/MS thermo TSQ vantage, c18 column 250x4.6 x5u, ESI, positive mode, MP ACN/Acid formic at 1ug/mL of Piracetam. Unfortunately i can't find any peak at 143, 125.8 or 97.9 m/z. so anyone can explain this problem for me ? thanks so much.

[Arkcon]

It would help if we knew what you've tried so far.  For starters, can you infuse, with a syringe, directly into your MS a dilute solution of your standard and get the proper results?

[MOTOBALL]

I am not familiar with your MS system, but am familiar with triple quadrupole systems in general and make the following points.  You need to establish at what point the system is not working.

As Arkcon suggests, what do you see with an authentic, dilute solution ?

1. Does Full-scan work fine ? Q1 only, or both Q1 and Q3 ?

2. Does Autotune run successfully ?; again Q1 only, or Q1 and Q3 ?

3.  Do you generate abundant parent ions [M+H]+ ??
If not, do either the source or rods (Q1), or both, need cleaning ??
Have you recently cleaned and not re-assembled correctly ??

Failure to detect fragment ions has (at least) three causes, in addition to failing electron multiplier which reduces sensitivity.

(a) failure to fragment parent ions (no gas in Q2 or collision energy too low OR settings too high which will lead to scattering losses)

(b) if the fragment ions are produced, Q2 fails to transmit them to Q3

(c) fragment ions are transmitted to Q3, which fails to operate correctly in the MRM or full-scan mode (not clear which mode you are using)

Detectability problems to me suggest issues with (i) condition of ESI probe and source (cleanliness; not blocked etc) or (ii) power supplies (either a board is failing, or possibly there are loose electrical connections on the quads.), (iii) failing multiplier.

Please let us know how this issue is resolved.

Good Luck !