= Ion suppression
\b[Ion suppression] is a reduction in the <mass spectrometry> response of an <analyte> caused by other sample constituents affecting ion production or the ion source response. The same amount of <analyte> can consequently yield a smaller signal in a complex sample than in a reference solution. It is one direction of a <mass spectrometry matrix effect>; enhanced response is also possible. A weak peak therefore need not mean that less analyte was originally present.
A 2003 experimental study separated matrix-response effects from analyte recovery in quantitative <liquid chromatography>–<mass spectrometry>. For its investigated compound, changing from ion spray to a heated-nebulizer interface removed a matrix effect under otherwise matched sample preparation and chromatographic conditions. This is evidence that the source interface matters, rather than a guarantee that one interface avoids suppression for every compound.<Strategies for the assessment of matrix effect in quantitative bioanalytical methods based on HPLC-MS MS by B. K. Matuszewski and others>[Abstract: recovery/matrix distinction and matched interface comparison.]{ref}
An original matched-spike example distinguishes two losses. Give equal final analyte amounts to a neat reference and to an extracted blank sample after preparation. Suppose their peak areas are $1000$ and $400$: the relative matrix response is $400/1000=0.40$, corresponding to $60\%$ suppression relative to the reference. Now spike the same nominal amount before preparation; an area of $240$ gives an estimated recovery of $240/400=0.60$ and overall process response $240/1000=0.24$. This interpretation assumes matched final volumes, injections and response conditions. It separates material lost during preparation from reduced response of material that remains.
<Detector signal clipping> is a different mechanism: a recording ceiling can lose intensity after ions have been produced. Neither that loss nor analyte-specific <ion suppression> is generally repaired by <total ion current normalization>. Distinguishing the mechanisms requires controls at the stages where the signal can change.
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