Ethephon by LC MSMS

[mauricio]

Hello
I am currently implementing a method to analyze residues of ethephon in grapes by LC MSMS.
I am following the technique published in CRL Pesticides.

The standard of ethephon get a good chromatography, but when added to the matrix, it disappears completely.

Has anyone worked with this analyte

Thanks

[oscarBAL]

Hello Mauricio.
I really do not have experience analyzing Ehtefon; but I Would do an extra test that could be help to see if ehtefon could be loosing in sample perp or by ion ssupretion.

1. I would prepare the sample and to the final extract spike the STD.
2. Also to othe "sample" spike the STD and do the extraction; inject both.

If in the first sample you get your peak but not in the send one then your sample prep need to be reviewd care fully; but if you do not see any peak in your first sample; then maybe Ion ssupretion could be happening.

You do not you SPE for this prossedure? I think to use SAX SPE could help if oyu have sample perp problem.

Any way this is only my opinion and very subjective by the way. only could help to discard possibilities.

Best Regards.

Oscar.

[Widebore]

I have found that QUECHERS removes anything with an acid group on it. Do a straight extraction with acetonitrile and not using MgSO4/PSA and you'll find out is is the dispersive solid pahse removing this compound. There are quite a few manufacturers QUECHERS methods that include compounds that are unsuitable for that method.

[H.Thomas]

You can try this method
http://www.crl-pesticides.eu/library/do ... CrlSrm.pdf