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deepakpangavhane
Junior

India,
2018-09-03 08:28

Posting: # 19205
Views: 282
 

 recoveries more than 100% [Bioanalytics]

Hi everyone!

The % recovery was 107.80%, 112.65% and 105.92% for the low quality control (LQC) and middle quality controls (MQC2 and MQC1), respectively. Whereas % recovery for higher quality control (HQC) was 98.25%.

The % recovery was determined by comparing the mean peak area of 6 replicates of extracted quality control samples at High, Middle and Low concentrations against respective mean peak area of 6 replicates of un-extracted quality control samples at High, Middle and Low concentrations. Internal standard used was deuterated.

Kindly confirm recoveries markedly higher than 100% for LQC, MQC2 and MQC1 are acceptable as per USFDA guidelines?? Also specify reason for higher recoveries.
Ohlbe
Hero

France,
2018-09-03 19:21

@ deepakpangavhane
Posting: # 19231
Views: 229
 

 recoveries more than 100%

Dear Deepak,

» The % recovery was determined by comparing the mean peak area of 6 replicates of extracted quality control samples at High, Middle and Low concentrations against respective mean peak area of 6 replicates of un-extracted quality control samples at High, Middle and Low concentrations.

Meaning that what you observe is a mix of extraction recovery and matrix effect. If you want to see the true extraction recovery you have to compare to samples spiked post-extraction. You can combine with matrix effects experiments.

» Internal standard used was deuterated.

Makes no difference. You are looking at peak areas, not peak area ratios.

» Kindly confirm recoveries markedly higher than 100% for LQC, MQC2 and MQC1 are acceptable as per USFDA guidelines??

Did you see any limit for absolute recovery in either direction in the FDA guidance ?

» Also specify reason for higher recoveries.

Multiple. The most probable: analytical variability (your results are well within the 15 % acceptance limits for precision and accuracy). Other possibilities include ion enhancement, sample preparation, calculation errors...

Regards
Ohlbe
Ladi
Junior

Thailand,
2018-09-04 03:51

@ deepakpangavhane
Posting: # 19232
Views: 209
 

 recoveries more than 100%

Hello Deepak and Ohlbe,

» The % recovery was 107.80%, 112.65% and 105.92% for the low quality control (LQC) and middle quality controls (MQC2 and MQC1), respectively. Whereas % recovery for higher quality control (HQC) was 98.25%.

My lab called the 'post-extraction' as 'un-extracted', I am guessing you also mean that?

I observed recovery 100-115% mostly with protein precipitation projects in our lab. My explanation to auditors was that the extracted samples are little bit more concentrated than the post-extracted samples because some protein is precipitated out in extracted samples. While in the post-extracted samples, the measured volume of supernatant from precipitated blank is use to make up a required concentration. Ususally for protein precipitation, recovery is almost 100%. So if extracted is more concentrated than it supposed to be (expected conc.), recovery may cross 100%. However, I normally see similar %recovery across all concentrations.

Regards,
Ladi
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