Accounting for matrix effects of pesticide residue liquid chromatography/electrospray ionisation mass spectrometric determination by treatment of background mass spectra with chemometric tools

Abstract

Matrix effect (ME) - ionisation suppression or enhancement - in liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI-MS) is caused by matrix components co-eluting with the analytes. ME has a complex and not fully understood nature. ME is also highly variable from sample to sample making it difficult to compensate for. In this work it was studied whether the background ion signals in scanned mass spectra of the LC effluent at the retention time of the analyte offer some insight into the presence and extent of matrix effect. Matrix effects for six pesticides - thiabendazole, carbendazime, methomyl, aldicarb, imazalil and methiocarb - in garlic and onion samples used in the study varied from 1% (suppression 99%) to 127% (enhancement 27%) depending on the pesticide and sample. Also standards in solvent and solvent blanks were included in the study. The ions most strongly varying from sample to sample - and therefore best describing the changes in sample composition and ME - were selected for quantification according to principal component analysis (PCA) for all six pesticides under study. These ions were used to account for ME via partial least-squares (PLS) regression. The calibration set was constructed from 19 samples and standards and the obtained calibration function was validated with seven samples and standards. The average errors from the test set were from 0.05 to 0.27 mg/kg for carbendazim and imazalil, respectively (the respective average pesticide concentrations were 0.22 and 0.88 mg/kg). The PLS results were significantly more accurate compared to the conventional solvent calibration resulting in average errors from 0.07 to 0.69 mg/kg for carbendazime and methiocarb, respectively.

Study of liquid chromatography/electrospray ionization mass spectrometry matrix effect on the example of glyphosate analysis from cereals

“…As an alternative approach background ions could be used to correct for the matrix effect, as has been previously described for other pesticides in complicated matrices …”

“…As an alternative approach background ions could be used to correct for the matrix effect, as has been previously described for other pesticides in complicated matrices. [27] CONCLUSIONS The aim of this study was to examine the influence of cereal type, cereal particle size and analyte concentration on the matrix effect in analysis of glyphosate. It was found that wheat and rye give very different matrix effect values in analysis of glyphosate using the glyphosate-FMOC derivative.…”

Method Development for Sulfonylurea Herbicides Analysis in Rapeseed Oil Samples by HPLC–DAD: Comparison of Zirconium-Based Sorbents and EMR-Lipid for Clean-up of QuEChERS Extract

“…Matrix interference (MI%) was calculated according to following Eq. (2): where A denotes peak areas of the standard (A Standard ) and the blank matrix extract (A Post extraction spike ) spiked at the same concentration level (Kruve et al 2011). Ideally, value of 0 is related to the absence of matrix interference.…”

Untargeted metabolomic analysis using liquid chromatography quadrupole time-of-flight mass spectrometry for non-volatile profiling of wines

“…The compounds causing the matrix effect can be of different origins and have different properties. In JetStream technology, analytes eluting close to the dead time/solvent front of the LC run and non-retained hydrophilic compounds cause an ion suppression effect [20]. This effect caused a decrease in sensitivity to some metabolites and, in some cases, their loss.…”