Spiking recovery above 100%...why?

[Anna01]

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A quick question...how is it possible to have recovery consistently between 102-110% when spiking serum samples?

I am spiking with the highest standard. The standards are made in spiked bovine serum albumin PBS buffer...The standard curves are nice and linear.

Just curious...anyone got an idea?

[Uwe Neue]

Plasma can both enhance and suppress the response of an analyte. It appears that you caught a case of ion-enhancement...

[Anna01]

I can understand that if the internal standard is slightly different. But is it really possible that ionenchasement/suppression can produce 108% recovery when doing isotope dilution ms/ms?

[Uwe Neue]

Why not? The enhanced or suppressed response can be caused by the mess between MS1 and MS2.

[Peter Apps]

Is the blank clean - i.e. no peak at the traget retention time ?

Peter