Particle bombardment matrix effects

An alternative way is given by the internal standard method, in which a particular element (most often yttrium) is added in known quantity to the sample to be analyzed. Special care should be taken of homogeneous mixing during addition. In this method an absolute determination of the bombarding particle current is not essential, furthermore matrix effects are well accounted for. The use of thick multielemental standards offers a relatively fast and simple way. However, differences in the composition of standards and samples to be analyzed make matrix corrections necessary if improved accuracy is needed. 

Figure 1. (A) Fast Atom Bombardment (FAB) the sample is dissolved in a liquid matrix and ion-ization/desorption is effected by a high energy beam of particles fired from an atom or ion gun. (B) Matrix Assisted Laser Desorption Ionisation (MALDI) the sample is dried on a metal target in the presence of a chromophoric matrix and sample ions arc produced by energy transfer from matrix molecules that have absorbed energy from the laser pulse. (Q Electrospray (ES) a stream of liquid containing the sample of interest enters the source through a capillary interface, where the sample molecules are stripped of solvent, leaving them as multiply charged species.

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