= B. K. Matuszewski
{c}
\b[B. K. Matuszewski] is an author of experimental research on quantitative <high-performance liquid chromatography> with <tandem mass spectrometry>. A2003 paper with collaborators, listing an affiliation at Merck Research Laboratories in West Point, Pennsylvania, develops ways to distinguish an <analytical matrix effect> from <extraction recovery>. The byline identifies the author with these initials.<Strategies for the assessment of matrix effect in quantitative bioanalytical methods based on HPLC-MS MS by B. K. Matuszewski and others>[byline, affiliation and Abstract]{ref}
The scientific problem is that an instrument signal can change even when the amount of <analyte> reaching the measurement is unchanged. Other constituents of the <sample matrix> can suppress or enhance the response. Conversely, analyte can be lost during sample preparation without changing the response per unit amount. A low measured signal therefore need not identify which mechanism occurred.
An original three-preparation example separates these effects under a linear-response assumption. Suppose equal nominal amounts of an analyte are introduced into: a clean solvent standard; a blank sample extract after extraction; and a sample before extraction. Match the final volumes and measurement conditions. Let the resulting background-corrected signals be $A=100$, $B=80$ and $C=60$ arbitrary units, respectively. The dimensionless ratios are
$$
\text{matrix response ratio}=\frac{B}{A}=0.80,\qquad
\text{extraction recovery}=\frac{C}{B}=0.75,\qquad
\text{overall response ratio}=\frac{C}{A}=0.60.
$$
The last ratio is the product of the first two. Calling the overall60percent response an extraction recovery would conflate analyte loss with <ion suppression>. This is an invented calculation, not a reconstruction of the paper's validation data. It assumes that the post-extraction addition represents the matrix response experienced by the extracted analyte.
Matuszewski and colleagues also compared ion-spray and heated-nebulizer interfaces while holding sample preparation and chromatographic conditions otherwise the same. For their investigated compound, a matrix effect appeared with the ion-spray interface and was absent with the heated nebulizer.<Strategies for the assessment of matrix effect in quantitative bioanalytical methods based on HPLC-MS MS by B. K. Matuszewski and others>[Abstract, final two sentences]{ref} That controlled comparison shows why selectivity in <mass spectrometry> must be tested for the actual method and <sample matrix>, rather than inferred from the detector's nominal specificity.
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