“Punkteinwaage” [Bioanalytics]

posted by Ohlbe – France, 2017-02-23 17:15 (2612 d 01:22 ago) – Posting: # 17101
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Dear Helmut,

❝ If you use different stock solutions you would get identical concentrations only if the analyst managed to achieve a <lang="de"> Punkteinwaage </lang="de"> (sorry, don’t know the English term), i.e., weigh-in identical – desired – amounts. Since this is very difficult, it is common sense that concentrations of calibrators and QCs generally differ (slightly).


What some labs do is that they adjust the volume of stock solution or intermediate solution that they take, to compensate for the slight difference between the desired weight and the actual weight, so that they get concentrations with round figures (e.g. pipet 998.5 µl instead of 1 ml). I don't see the point, but that's their choice. In the same way, it would be possible to adjust the volumes taken from both solutions to get the same nominal concentration for a QC and a calibration sample.

Regards
Ohlbe

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