Good peak separation of pesticides by GCMS

[Louise Kehoe]

I'm trying to separate a mix of organophosphorus and organochlorine pesticides and triazine herbicides. Is it possible to separate coeluters or do I need to run the standards separately. TIA

[HPLC chemist]

Probably separately (better to be safe than sorry)! There is no guarantee if you use the same chromatographic conditions that they will interfere with one another (coelute).

With an LC/MS/MS you can use a 'selected ion mode' and look for P, Cl, N...but who knows?

[Louise Kehoe]

T

Probably separately (better to be safe than sorry)! There is no guarantee if you use the same chromatographic conditions that they will interfere with one another (coelute).

With an LC/MS/MS you can use a 'selected ion mode' and look for P, Cl, N...but who knows?

Thanks

[HPLC chemist]

Remember, the chromatographic conditions WILL be different because the LC/MS/MS uses a smaller column. This alone changes the ratio of your solute (molecule of interest) between the mobile phases and stationary phases.

[Rndirk]

What exactly are you trying to do? Pesticide analysis is typically done by GC and LC - MS(/MS). Some pesticides are better on GC, others on LC and some can be done on both. The three groups you mention are nice examples: for organochlorine i'd use GC, triazines LC and organophosphorous can be done on both.

Is it possible to seperate coeluters? If i understand your question correctly => Yes: if they have a different mass/transition

[adler_LAB]

The separation can be influenced by so many factors on GC.
For a good start i would contact a column producer, they usually have a few methods for pesticides on their products.

That gives you a pre setting that you can adjust or learning from it.

[mckrause]

You have a MS. Why do you need to separate the compounds? Are you trying to look for isomers?

Given your mixture, and assuming that you aren't just talking about 2 or 3 total compounds, it is highly unlikely that you will be able to chromatographically resolve all of the compounds. This is why you use a MS.