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Topic: % Recovery of spiked Analyte >100%. Violation of Thermodynamic Law?  (Read 4982 times)

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Offline Golden_4_Life

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I have been reading via a literature search in journals such as "J. Chromatog." "Acta Chroma." etc.  It seems that a common theme in many method validation studies is that the amount of analyte "found" is frequently 105% to 120% of the analyte "spiked" in.  How on Earth can this be?! The first law of thermo says "matter is neither created nor destroyed".  How can these researchers be recovering more analyte than was gravimetrically put into the matrix?
I am at a loss for an explanation and have not heard a lucid one yet.
Any help is appreciated.
Thanks, Golden.
Golden4Life

Offline JGK

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Re: % Recovery of spiked Analyte >100%. Violation of Thermodynamic Law?
« Reply #1 on: October 23, 2009, 03:55:39 PM »
No method of analysis is perfect what you are seeing could be the cumulative results of "human error or variation" conpiring agaist you to produce a value above the 100% mark. You havent violated the thermodynamic law you just havent got a great measurement.


If methods of analysis were perfect calibrations would all be linear and the lines would pass through the origin (0,0).
eyesight would be 20/20 or better and you could hit the line on a volumeric pipette to with a nanometer.
solutions would be totally homogeneous every time and all equipment would be impervious to outside interference.

Alas this is not the case and I still can't buy a fully functional tricorder.
Experience is something you don't get until just after you need it.

Offline Golden_4_Life

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Re: % Recovery of spiked Analyte >100%. Violation of Thermodynamic Law?
« Reply #2 on: October 27, 2009, 02:07:50 PM »
HEHEHeh: well that was at least an entertaining reply to my query.
Golden4Life

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