Odd QC values but not outliers [Bioanalytics]

posted by Ohlbe – France, 2017-09-19 15:49 (2698 d 16:15 ago) – Posting: # 17818
Views: 5,263

Dear Thi Nguyen,

In addition to ElMaestro's comments and questions:

❝ LLOQ and all other QCs (LQC, MQC, HQC) were prepared in bulk by spiking solutions into 10 ml plasma then aliquoted into small vials (enough for 2 replicates in assay) so LLOQ are homogenous, it shouldn't cause one very high, another from the same vial normal.


OK, so it doesn't look like a spiking error.

❝ And yes, the concentrations measured match with the nominal concentration (accuracy were quite good, most of them around 100%). The abnormal only happened with LLOQ, but not with any other QCs.


Right. My question was also: does the measured concentration of these problematic LLOQ samples match with the nominal concentration of e.g. HQC or CC7 or whichever other spiked sample ? It could be simply a labelling error after aliquoting, or taking the wrong sample out of the freezer.

❝ No carry-over was observed at all, and the LLOQ with high values were not following any ULOQ in the run.


OK. Could it be a contamination at some point ? How do you process the samples: manually, or in 96-well plates with robotic equipment, or what ?

Regards
Ohlbe

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