We are having issues with our PBDE method on GC-MSMS. We had a method developed using applications from Agilent for GC and MSMS conditions. When we run linearity, it seems our surrogates and/or internal standards increase in concentration as the native standard concentration increases (like a linear correlation) when they are all added at the same level. This effect occurs with the higher massed analytes, primarily Octa, Nona and Deca-BDE.
We have tried manufactured standards, making our own from serial dilution, different columns, different injection volumes and sandwiched techniques.
The current method uses a pulsed spitless injection with gradient temperature in the MMI. When we tried a splitless technique or isocratic MMI we could not see BDE-209 (deca).