Why the recovery of bio-analytical validation is always more

[wxmwqr]

Why the recovery of bio-analytical validation is always more than 100%?
I study the triterpenoid pharmacokinetics in rats, when I study the method validation I found that the recovery of all QC samples are more than 100%. I want Know what cause this?
I had read many papers in which the recovery are less than 100%.

[tom jupille]

Bioanalytical analyses typically have a fairly high CV (compared to something like potency assay); you are looking at low levels in complex matrices.

Given the CV and the number of replicates, you should be able to calculate the confidence interval for your recovery (at whatever confidence level you require). If this interval includes 100%, it should not be a problem.

[bert]

wxmwqr,

if your first sample prep step is deproteinization in the sample tube, for instance using acid or acetonitrile, this step may concentrate your analyte in the upper waterphase.

regards, Bert