Investigation of matrix effects in bioanalytical high‐performance liquid chromatography/tandem mass spectrometric assays: application to drug discovery

Abstract

A series of studies was performed to investigate some of the causes for matrix effects ('ion suppression' or 'ion enhancement') in bioanalytical high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) assays. Previous studies have reported that matrix effects are mainly due to endogenous components in biological fluids and are a greater concern for electrospray ionization (ESI) than for atmospheric pressure chemical ionization (APCI). In this report we demonstrate that: (1) matrix effects can also be caused by exogenous materials, such as polymers contained in different brands of plastic tubes, or Li-heparin, a commonly used anticoagulant; (2) matrix effects are not only ionization mode (APCI or ESI) dependent, but also source design (Sciex, Finnigan, Micromass) dependent; and (3) for at least one vendor's design, we found the APCI mode to be more sensitive to matrix effects than the ESI mode. Based on these findings, we have proposed the following simple strategies to avoid matrix effects: (1) select the same brand of plastic tubes for processing and storing plasma samples and spiked plasma standards; (2) avoid using Li-heparin as the anticoagulant; and (3) try switching the ionization mode or switching to different mass spectrometers when matrix effects are encountered. These three strategies have allowed us to use protein precipitation and generic fast LC techniques to generate reliable LC/MS/MS data for the support of pharmacokinetic studies at the early drug discovery stage.

Adduct formation in quantitative bioanalysis: Effect of ionization conditions on paclitaxel

“…Nevertheless, some challenges still remain when performing quantitative LC-MS. An important issue is matrix suppression, a less efficient ionization of the target compound in the presence of other molecules. This phenomenon is well recognized and described in an increasing number of publications [1][2][3][4]. Another complexity in quantitative LC-MS is adduct formation.…”

Matrix effect in bio-analysis of illicit drugs with LC-MS/MS: Influence of ionization type, sample preparation, and biofluid

“…Matrix effect is defined as the effect of co-eluting residual matrix components on the ionization of the target analyte. Typically, suppression or enhancement of analyte response is accompanied by diminished precision and accuracy of subsequent measurements [11][12][13]. Matrix effect thus limits the utility of LC-MS for quantitative analysis.…”

Steroid-estrogen determination in sediment and sewage sludge: a critique of sample preparation and chromatographic/mass spectrometry considerations, incorporating a case study in method development

“…The aim of LC/MS is to separate individual analytes by HPLC such that the eluent delivered to the electrospray ionisation source contains analytes that are resolved from other matrix components. It has been proposed that longer run times and multistep clean up procedures may minimise matrix effects, and also recognised that although improving resolution may reduce matrix effects, problems related to hydrophobic components with retention times which overlap analysis are perhaps most difficult to eliminate [35]. Such effects were observed in this work, the extended run programme using…”

“…Studies on the occurrence of matrix effects in the determination of drugs from biological fluids have also indicated that exogenous materials leached from sample handling during analysis may also play a role in causing matrix effects in LC/MS [35], and consideration should be given to such sources in evaluating methods used for environmental samples.…”