Chromatography Forum

Hi everyone,

I am doing pesticide residue detection via LCMSMS, and there is one "problem" pesticide Fenchlorphos.
It is hard to optimize the MRM method for it, I study some paper and most of them are about GCMSMS detection.
I am wondering how to make GCMSMS detectable analyte also be detected by LCMSMS.
I tried MRM of 321>125 and 321>285 for Fenchlorphos, however, the retention time of those peaks are different with 0.2 mins.

I would update more detail about tune file later.

By the way, I would also like to ask if there are any good solution for peak shoulder problem, I did prepare fresh mobile phase and changed the solvent of standard to match the initial gradient mobile phase composition. Could this problem caused by buffer?
Please share if you know, thank you very much.

http://www.chem.agilent.com/Library/app ... 3774EN.pdf

Fenclorphos = Ronnel

From the spectrum Agilent shows in that link, 321-245 might be a good transition. However, GCMS might be a more sensitive detection technique. If you can get it to fly and meet your reporting limits, then you're good to go. Otherwise, might need to run by GCMS.

Are you using ESI(positive or negative) or APCI?

http://www.chem.agilent.com/Library/applications/5988-3774EN.pdf

Fenclorphos = Ronnel

From the spectrum Agilent shows in that link, 321-245 might be a good transition. However, GCMS might be a more sensitive detection technique. If you can get it to fly and meet your reporting limits, then you're good to go. Otherwise, might need to run by GCMS.

I tried 321>245 transition today, the signal is quite weak but same RT with 321-285. I would see if there is any better parameter for these two transition.
Thank you so much for your suggestion.

Are you using ESI(positive or negative) or APCI?

I use ESI+ for the ionization.

Your compound is rather polar, so it "might not want to go out of the ESI droplet" and therefore sensitivity for trace analysis might not be achievable. If LoD is very important you can try to derivatize the analyte with some apolar group that will increase your molecules affinity towards ESI droplet surface and therefore raise the sensitivity.

I tried Fenclorphos several times on LCMSMS but didn't have much luck. I had to run it GCMS.

Here is one of the best comprehensive lists for LCMSMS analysis for pesticides I have seen:

http://www.bfr.bund.de/cm/349/list_of_p ... resent.pdf

I did not see Fenchlorphos(Ronnel) on the list for LCMSMS.

I used that list when working on trying to analyze over 300 pesticide compounds on a single run, and the transitions are very reliable using the mobile phases listed for each.

Here is a link to another paper that shows a large list of pesticides which work for both LCMSMS and GCMSMS.

http://link.springer.com/article/10.100 ... 007-1425-6

(I have a copy of that one if you can't access it)

I tried Fenclorphos several times on LCMSMS but didn't have much luck. I had to run it GCMS.

Here is one of the best comprehensive lists for LCMSMS analysis for pesticides I have seen:

http://www.bfr.bund.de/cm/349/list_of_p ... resent.pdf

I did not see Fenchlorphos(Ronnel) on the list for LCMSMS.

I used that list when working on trying to analyze over 300 pesticide compounds on a single run, and the transitions are very reliable using the mobile phases listed for each.

Here is a link to another paper that shows a large list of pesticides which work for both LCMSMS and GCMSMS.

http://link.springer.com/article/10.100 ... 007-1425-6

(I have a copy of that one if you can't access it)

Thank you for your reference sources, those are very useful material!!
As this is the only 1 left for optimization, my adviser strongly like me to finish it with LCMSMS method....
So I have no choice but try LCMS or LCMSMS method only.

Your compound is rather polar, so it "might not want to go out of the ESI droplet" and therefore sensitivity for trace analysis might not be achievable. If LoD is very important you can try to derivatize the analyte with some apolar group that will increase your molecules affinity towards ESI droplet surface and therefore raise the sensitivity.

I see your point.
I also tried ESI- and it seems give a better peak for 20 ppb.
In fact, LOD is very important to my project, but I would like to know if derivatize analyte affect other pesticide.

which other pesticides are you determining?

which other pesticides are you determining?

Here is the list of other pesticides, all of them are organophorphous pesticide:
Chlorfenvinphos
Dichlorvos
Azinphos-methyl
Diazinon
Fenitrothion
Fenthion
Profenofos
Quinalphos
Trichlorfon
Chlorpyrifos
Pyrazophos
Carbophenothion
Disulfoton
Edifenphos
Ethion
Tetrachlorvinphos
Chlorpyrifos-methyl
Fenamiphos
Pirimiphos-methyl
Phosphamidon
Acephate
Malathion
Monocrotophos
Methidathion
Fensulfothion
Phorate
Coumaphos
Methamidophos
Omethoate
Parathion-methyl
Parathion-ethyl
Dimethoate
Sulfotep
Triazophos
Prothiophos
Isofenphos
Phosalone
Phosmet
Ethoprophos
Mevinphos
Phenthoate
Isocarbofos
Crufomate