Posted: Thu Oct 23, 2008 3:33 pm
Just because your IS is an Isotopic analogue does not mean it will behave differently. Using isotopic analogues is normally preferred because they behave identically to the analyte.To JGK:
You might be right that a fraction of my analyte is "bound" to part of the matrix, although this comes very unexpected to me. Besides I use an isotopic anologue as IS, which should compensate for this. Earlier I have tried adding ACN to precipitate proteins and strong acids, neither did any difference.
Still (very) stuck
If your analyte/IS binds aggressively to protein, deproteination will not help