Miroslav Ryska
Quinta-Analytica s.r.o., Czech Republic
Biography
The source of the “Matrix effect” as a consequence of analyte ions suppression or ions enhancement must be sought in the presence of unknown impurities from matrix. They are participating in the complex ionization process in parallel or competing ion-molecular reactions. Not only impurities from extracts but impurities adsorbed in the ion source and/or in the analytical system may play an important role. These adsorbed substances cannot be fully removed from the system by any cleaning procedure.
To fully compensate for the negative impact of the “Matrix effect“, use of isotopically labeled internal standards (isotope dilution technique) proved to be the only effective technique. This applies especially to LC/MS/MS determination of drugs and their metabolites in complex extracts of biological matrices. The isotope dilution technique is successful regardless of the method of purification, the ionization technique (APCI or ESI) and the type of the equipment used. The isotope dilution technique proved to be 100% effective for the compensation of matrix effect influences in 181 analytical methods developed and validated. The strict requirements of EMA guidelines to investigate different plasma sources for the assessment of the matrix effect in the analytical method validation are discussed.