Correction of Matrix Effects for Reliable Non-target Screening LC–ESI–MS Analysis of Wastewater

Abstract

Matrix effects are well-known challenges for accurate and comparable measurements with liquid chromatography (LC) electrospray ionization mass spectrometry (ESI–MS). This study describes a three-step method to evaluate and compensate for matrix effects in enriched wastewater extracts using LC ESI-high-resolution MS (HRMS). As a first step, the “dilute and shoot” approach was used to determine the optimal relative enrichment factor (REF) for a direct comparison between wastewater influent (REF 10) and effluent (REF 50) extracts. However, the rapid decrease in the number of non-target compounds detected with increasing dilution leads to the need for a correction of the matrix effect for analyzing samples with higher REFs. As a second step, the observed matrix effect at higher REFs was corrected by the retention time-dependent matrix effect. A new scaling (TiChri scale) of the matrix effect was introduced, which demonstrates that the total ion chromatogram (TIC) predicts the matrix effect as effectively as post-column infusion (PCI) approaches; thus, the average median matrix effect was improved from −65 to 1% for influent (REF 100) and from −46 to −2% for effluent extracts (REF 250). The TIC traces for concentrated (REF 250) influent and effluent samples were successfully used to correct the matrix effects and allowed the extent of micropollutant degradation in three WWTPs to be quantified. As a final step, the residual structure-specific matrix effect was predicted and corrected by quantitative structure–property relationships (QSPR), which led to a further correction of the matrix effect to 0 ± 7% for 65 compounds.

Estimation of the concentrations of hydroxylated polychlorinated biphenyls in human serum using ionization efficiency prediction for electrospray

“…Coping with matrix effect is cumbersome in targeted analysis where isotopically labelled standards are most effective but sample dilution [ 12 ], extrapolative dilution [ 13 ], matrix matching, and (post-column) standard addition [ 14 ] have also been investigated. Recently, Tisler et al [ 15 ] have proposed a three-stage approach for accounting for matrix effect in non-targeted screening which includes sample dilution, total-ion-count-based correction, and quantitative structure property relationship (QSPR) modelling of matrix effect. Therefore, the quantification of PCB metabolites in non-targeted LC/ESI/HRMS analysis requires overcoming the burden of restricted chemical space and ionization suppression occurring in ESI.…”

Supercritical Fluid Chromatography Coupled to High-Resolution Mass Spectrometry Reveals Persistent Mobile Organic Compounds with Unknown Toxicity in Wastewater Effluents

“…In our pooled QC wastewater effluent samples (enrichment factor 50), the RT-dependent matrix effect for LC was most of the time <−10%. For SFC, the matrix effect was between −10 and −37%, which means higher signal suppression by a higher competition for ionization . This results in smaller peak areas for analyzed compounds, which could lead to underestimation of the true analyte concentration in the absence of a perfect matching IS.…”

“…The analytical conclusion of influent samples can be limited, because of higher ion suppression due to matrix effects. 12 Thus, influent samples were only considered for plausibility checks without correcting for matrix effects, to evaluate if compounds were occurring already in the influent or formed during the treatment process. WWTPs W1−W4 have uplands located in densely populated areas with mixed industries and hospitals.…”

A non-target screening study of high-density polyethylene pipes revealed rubber compounds as main contaminant in a drinking water distribution system

“…Very polar acidic or basic compounds might have low recovery on the used HLB method. Alternatively, multilayer SPE has been used in literature (Tisler et al, 2021) to increase the recovery of these polar compounds.…”