Hi folks,

i have the following problem: i need to quantify 3-alanin amide (3-apa) in food products by lcms.
there is a publication using dansyl chloride for derivatisation (in potatoes), but this does not work properly for other ("dirtier") products, such as coffee or cereals. it seems that more complex matrices "eat away" the derivatisation agent. as a result, the intensity of the signal gets very weak. diluting the sample is no alternative, as the i cannot reach the required sensitivity.

the workup procedure is (in short) as follows:
1. add internal standard and then water to the sample, ultra turrax.
2. carrez precipitation (zn-sulfate/k-hexa cyanoferrate)
3. centrifugation
4. transfer aliquot into new vessel
5. add derivatisation agent, shake, leave for 1h
6. extract derivative with dichloromethane
7. flash evaporate solvent
8. redissolve in methanol/water
9. measure with lcms (rp phase, water/methanol)

i have tried fmoc as alternative derivatisation agent as i am sure that the problem is mainly that dansyl chloride has a low solubility and the concentration of the agent is too low to derivatise a reasonable amount of the analyte. fmoc has a very good solubility and performs well as derivative but the problem remains almost the same: derivatisation rate is too low.

what i have tried as well: measure 3-apa directly without derivatisation - works perfectly in standard solutions, but as soon as i have matrix involved, the signal is strongly suppressed. this is especially the case when i use carrez for precipitation (somehow the metal ions seem to form a complex with 3-apa), i have observed this in standard solutions when i added one of the components of carrez.

my question is now, whether or not it could be useful to use an ionpair reagent in this case? 3-apa forms a hydrochloride, so my guess is that a strong ionpair reagent could do...?

thanks in advance,

philipp