Rapid ion-exchange matrix removal for a decrease of detection limits in the analysis of salt-rich reservoir waters for fluorobenzoic acids by liquid chromatography coupled with tandem mass spectrometry

Analytical and Bioanalytical Chemistry, Nov 2016

A matrix removal procedure with ion-exchange resin prior to analysis for 18 fluorinated benzoic acids (FBAs) tracers in saline (>25% salt) reservoir water was optimized. The elimination of >98% of salt and the simultaneous matrix sample cleanup allowed the direct analysis using the supernatant by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). This resulted in a gain in detection limits for most of the tracers in comparison with the reference method (direct analysis after minimum required dilution). The limits of detection (LODs) were in the range of 0.01–0.15 ng/ml and compared to other studies the developed method provided comparable limits of detection and advantage of simplified and shorter sample preparation. The presented method offers a considerable gain in simplicity and analysis time. Recoveries for all the tracers reached 80–100%, except for 2-FBA and 2,6-dFBA for which they were ca. 60%. The low recoveries were corrected by the use of five isotopically labeled internal standards. The method was validated by the analysis of spiked samples and by an independent comparison of the results with those obtained by solid-phase extraction LC-MS/MS method.

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Rapid ion-exchange matrix removal for a decrease of detection limits in the analysis of salt-rich reservoir waters for fluorobenzoic acids by liquid chromatography coupled with tandem mass spectrometry

Anal Bioanal Chem Rapid ion-exchange matrix removal for a decrease of detection limits in the analysis of salt-rich reservoir waters for fluorobenzoic acids by liquid chromatography coupled with tandem mass spectrometry Paweł Kubica 0 1 2 4 5 Véronique Vacchina 0 1 2 4 5 Tomasz Wasilewski 0 1 2 4 5 Stéphanie Reynaud 0 1 2 4 5 Joanna Szpunar 0 1 2 4 5 Ryszard Lobinski 0 1 2 4 5 0 CNRS-UPPA UMR 5254, Equipe de Physique et Chimie des Polymères (EPCP-IPREM) , Hélioparc, 2, Avenue Pr. Angot, 64053 Pau , France 1 UT2A, Hélioparc , 2, Avenue Pr. Angot, 64053 Pau , France 2 Department of Analytical Chemistry, Faculty of Chemistry, Gdańsk University of Technology , Narutowicza 11/12, 80-233 Gdańsk , Poland 3 Paweł Kubica 4 Department of Analytical Chemistry, Warsaw University of Technology , ul. Noakowskiego 3, 00-664 Warsaw , Poland 5 CNRS-UPPA, UMR 5254, Laboratoire de Chimie Analytique Bio-inorganique et Environnement (LCABIE-IPREM) , Hélioparc, 2, Avenue Pr. Angot, 64053 Pau , France A matrix removal procedure with ion-exchange resin prior to analysis for 18 fluorinated benzoic acids (FBAs) tracers in saline (>25% salt) reservoir water was optimized. The elimination of >98% of salt and the simultaneous matrix sample cleanup allowed the direct analysis using the supernatant by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). This resulted in a gain in detection limits for most of the tracers in comparison with the reference method (direct analysis after minimum required dilution). The limits of detection (LODs) were in the range of 0.01-0.15 ng/ml and compared to other studies the developed method provided comparable limits of detection and advantage of simplified and shorter sample preparation. The presented method offers a considerable gain in simplicity and analysis time. Recoveries for all the tracers reached 80100%, except for 2-FBA and 2,6-dFBA for which they were ca. 60%. The low recoveries were corrected by the use of five isotopically labeled internal standards. The method was validated by the analysis of spiked samples and by an independent comparison of the results with those obtained by solid-phase extraction LC-MS/MS method. Fluorinated benzoic acids; LC MS/MS; Matrix removal; Ion exchange Introduction Different fluorobenzoic acids are commonly used as nonradioactive passive tracers in petroleum exploration [ 1, 2 ]. Hence, there is a need for their sensitive analysis in oil reservoir waters, known for their highly dissolved organic matter and salt (NaCl, CaCl2) content often exceeding 25% [3]. Gas chromatography (GC) [ 4 ] or high-performance liquid chromatography (HPLC) [ 5–10 ] with MS/MS detection have been typically used to assure the separation of the tracer compounds from each other while assuring their specific detection. HPLC-MS/MS offers detection limits down to 0.01 ng/ml for most of the fluorobenzoic acids in the selected reaction monitoring (SRM) mode using the ion transition corresponding to the loss of CO2 by the pseudomolecular ion employing the-state-of-the-art triple quadrupole, Q-TOF [ 7 ] or QOrbitrap [ 11 ] mass spectrometers. However, as the maximum tolerable salt content in the solution injected on the column used (Waters, Acquity UPLC BEH C18 column, 50 × 2.1 mm, 1.7 μm) has to be inferior to 1%, a dilution is required [ 10 ]. This represents for samples with 25% salinity a 25-fold increase in the detection limits making the method virtually useless for practical applications. Sample preparation methods based on the solid-phase extraction (SPE) of fluorobezoic acids were therefore developed for the salt-removal and preconcentration of analytes. They allowed to obtain detection limits for salt-rich samples comparable with those obtained for standard solutions in water [ 4, 7, 8 ]. Moreover, methods presenting on-line SPE for determination of drugs or pesticides in different kind of sample are available as well [ 9, 10 ] However, the time necessary, relatively large volumes of organic solvents requiring evaporation made the procedures quite tedious for high-throughput analysis. Gas chromatography MS/MS suffers from similar drawbacks [11]. Although the detection limits are below 0.01 ng/ mL, the required sample preparation procedures are timeconsuming (24 h). Moreover, the derivatization step is incomplete and suffers from strongly compound-dependent yields which limits the practical use [ 11 ]. In contrast to all the reported protocols, until now [ 4, 7, 8 ], the objective of this method development was on the removal of the matrix rather than on the extraction of the analytes. The removal of salt matrix using mixed-bed ion-exchange resin was investigated. The proposed approach allows to remove matrix effects and thus resulting in a less noisy baseline and lower detection limits. Materials and methods Samples collection Samples originated from reservoir waters (Congo) contained 250 g/L of total salt (primary Na and Ca (...truncated)


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Paweł Kubica, Véronique Vacchina, Tomasz Wasilewski, Stéphanie Reynaud, Joanna Szpunar, Ryszard Lobinski. Rapid ion-exchange matrix removal for a decrease of detection limits in the analysis of salt-rich reservoir waters for fluorobenzoic acids by liquid chromatography coupled with tandem mass spectrometry, Analytical and Bioanalytical Chemistry, 2017, pp. 871-879, Volume 409, Issue 4, DOI: 10.1007/s00216-016-0060-5