06 Jul
2011

## Matrix effects in liquid-chromatography electrospray mass-spectrometry (LC-ESI-MS)

Posted by: Ivo Leito
On Jul 05, 2011 Anneli Kruve defended her PhD thesis Matrix effects in liquid-chromatography electrospray mass-spectrometry (LC-ESI-MS) at the Institute of Chemistry, University of Tartu.

Electrospray ionization (ESI, ESI ion source) is currently the most popular ionization mode in LC-MS (Liquid chromatography mass spectrometry, LCMS). LC-ESI-MS has become the premier technique for a large number of different analytical tasks, ranging form pesticides determination in fruit and vegetables to drug residues in sewage sludge. However, a major drawback of LS-ESI-MS is the so-called matrix effect – ionization suppression or enhancement of the analyte of interest by other compounds present in the sample and co-eluting with the analyte (see here for the definition of matrix effect). The matrix effect, if present, can cause large uncertainties in quantification using the LC-ESI-MS technique.

The thesis presents four original approaches for combating the LC-MS matrix effect developed by Anneli:

1. Extrapolative dilution;

2. Multilinear (PLS) calibration using background ions;

3. Taking matrix effect into account in measurement uncertainty of the analysis result;

4. Reducing matrix effects by optimization of ESI-MS parameters.

The first two approaches are essentially approaches for correcting for matrix effect. The third approach permits accounting for matrix effect via measurement uncertainty. The last one is about reducing matrix effect. These approaches, together with an investigation of the effect of sample preparation on ESI MS matrix effect and a comprehensive overview of LC-ESI-MS matrix effect in the introduction part make this thesis a genuine “LC-ESI-MS Matrix Effect Toolbox” for practitioners.

If you wish to read the above cited articles but do not have online access, please contact us.

(Sometimes the term matrix effect is used synonymously to “matrix suppression”. This is incorrect: matrix effect can sometimes also mean matrix enhancement. Sometimes the ESI-MS matrix effect is termed simply as MS matrix effect. These terms are not synonymous, as different effects are inherent in different ion sources.)

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Dear staff of University of Taru

i’d really like to be able to read the articles, because i am actually working in the develop of a multiresidue method for determining pesticides in fruits by LC – ESI MS/MS. I just realized i have problems with the matrix effect in the interface ESI, i was researching how to deal with this problem, and i found your web page.

I am very sure your investigation would be very useful to resolve my big problem.

Actually, we are not allowed to suscribe any web page for a while, that is why i am asking for your help with this articles.

Thank you so much for your time and for the help you are providing to all people involved in investigation.

Best Regards

Sergio Maquilon

Cromatography Department

Would the technique of standard addition take care of matrix effects in this case?

Standard addition is not a very capable echnique against ESI MS matrix effects, because it assumes linearity and matrix effects are often strongly non-linear. Our more recent investigations clearly show that the best technique against matrix effects is Extrapolative dilution.