Direct injection ESI-MS

[Andyp]

I'm considering the direct injection of a 5 component mixture of antibiotics into the ion source of a ZQ4000. I can simulate the matrix for quantitation. Is this an approach which is doomed to fail from the start? Should I put effort into developing a separation (there are both acids & bases in this sample)?

Thanks

[james little]

Hard enough to do with separation. Even a labelled standard can suppress/enhance analyte concentration in APCI and ESP.

We do some direct injection, but just for qualitiative analyses of relatively high level components.

For problems with matrix enhancement/suppression see

http://www.tandemlabs.com/capabilities_ ... tions.html

and

http://littledomain.com/james/files/matrix_effects.htm