Mass spectrometry process efficiency

Mass spectrometry process efficiency compares the response obtained after the entire stated preparation with the response from the same nominal analyte amount in a specified neat reference. It combines preparation loss and matrix-dependent response under the comparison conditions. It is therefore not simply the fraction of molecules physically retained.

Let $A$ be neat-reference peak area, $B$ the area from an extracted blank matrix spiked after preparation, and $C$ the area when the same nominal amount is spiked before preparation. With matched final volumes, injections and blank correction,The factors are mass spectrometry matrix factor and an estimate of extraction recovery. The decomposition separates quantities that the original method study evaluated independently.^[ref]

For invented areas $A=1000$, $B=500$, $C=400$, the matrix factor is $0.50$, recovery $0.80$, and process efficiency $0.40$. The same process efficiency could arise from matrix factor $0.80$ and recovery $0.50$. Equal overall response therefore does not identify the cause of reduced signal or which preparation change would help.

Response enhancement makes the terminology especially important. A stipulated matrix factor $1.5$ and recovery $0.8$ give process efficiency $1.2$, or120%. This does not require extraction to create more analyte; the measured response per retained amount is larger than in the reference. Conversely, low process efficiency can be highly reproducible while still reducing useful signal.

Keep the comparison basis explicit. Residual analyte in a nominal blank, unequal preparation volumes, nonlinear response or detector signal clipping can invalidate the simple ratios. Apparent compensation between enhancement and loss can hide two substantial effects behind an overall ratio near one.