TY - JOUR

T1 - A retrospective quantification study of benzoic acid, ibuprofen, and mecoprop in Danish groundwater samples

AU - Christensen, Peter

AU - Kristensen, Mette

AU - Hansen, Hans Christian B.

AU - Borggaard, Ole K.

AU - Christensen, Jan H.

N1 - Funding Information: Financial support for this work was provided by the Water Research Initiative at University of Copenhagen that funded the PhD project of Peter Christensen. Publisher Copyright: © 2022 The Authors

PY - 2022

Y1 - 2022

N2 - Target analysis of pre-selected compounds is the standard procedure for monitoring of groundwater quality. However, compounds, not included on the target list can still be present but are overlooked in this targeted approach. In a previous non-target screening (NTS) study, groundwater samples from catchments covering different land uses were analysed by solid-phase extraction, dispersive liquid-liquid microextraction with gas chromatography – mass spectrometry analysis (SPE-DLLME-GC-MS), where potential chemical markers for land-use, benzoic acid (natural metabolite), ibuprofen (pharmaceutical) and mecoprop (pesticide), were identified but not quantified. The aim of this study was to develop a strategy for retrospective quantitative analysis and to perform retrospective analysis of the identified chemical markers in SPE groundwater extracts stored frozen for 3 years. The stored extracts were derivatised to transform carboxylic acid functional groups into methyl-esters and further concentrated by DLLME and analyzed by GC-MS. Ibuprofen was detected in six replicates from one well in Haderup (0.0070 ± 0.0023 µg /L) and in one well from Skive (0.0032 µg/L) indicating anthropogenic input. Mecoprop was detected in two samples with concentrations of 0.0095 µg/L and 3.3 µg/L that can be ascribed to agriculture. Benzoic acid was detected in all samples in the range of 0.072 - 1.20 µg/L except for Jyderup Skov where concentrations up to 161 µg/L were found, probably originating from the coniferous forest dominating this site. A combination of NTS analysis and retrospective quantification showed to be a promising strategy for monitoring of land-use markers. The strategy is challenged by effects of storage and lack of selectively in the NTS sample preparation method. Two additional sample preparation steps were carried out in this study (derivatization and DLLME) to improve the selectivity and sensivitiy of the retrospective analysis.

AB - Target analysis of pre-selected compounds is the standard procedure for monitoring of groundwater quality. However, compounds, not included on the target list can still be present but are overlooked in this targeted approach. In a previous non-target screening (NTS) study, groundwater samples from catchments covering different land uses were analysed by solid-phase extraction, dispersive liquid-liquid microextraction with gas chromatography – mass spectrometry analysis (SPE-DLLME-GC-MS), where potential chemical markers for land-use, benzoic acid (natural metabolite), ibuprofen (pharmaceutical) and mecoprop (pesticide), were identified but not quantified. The aim of this study was to develop a strategy for retrospective quantitative analysis and to perform retrospective analysis of the identified chemical markers in SPE groundwater extracts stored frozen for 3 years. The stored extracts were derivatised to transform carboxylic acid functional groups into methyl-esters and further concentrated by DLLME and analyzed by GC-MS. Ibuprofen was detected in six replicates from one well in Haderup (0.0070 ± 0.0023 µg /L) and in one well from Skive (0.0032 µg/L) indicating anthropogenic input. Mecoprop was detected in two samples with concentrations of 0.0095 µg/L and 3.3 µg/L that can be ascribed to agriculture. Benzoic acid was detected in all samples in the range of 0.072 - 1.20 µg/L except for Jyderup Skov where concentrations up to 161 µg/L were found, probably originating from the coniferous forest dominating this site. A combination of NTS analysis and retrospective quantification showed to be a promising strategy for monitoring of land-use markers. The strategy is challenged by effects of storage and lack of selectively in the NTS sample preparation method. Two additional sample preparation steps were carried out in this study (derivatization and DLLME) to improve the selectivity and sensivitiy of the retrospective analysis.

KW - Benzoic acid

KW - Chemical marker for land use

KW - Groundwater

KW - Ibuprofen

KW - Mecoprop

KW - Retrospective analysis

U2 - 10.1016/j.envadv.2022.100180

DO - 10.1016/j.envadv.2022.100180

M3 - Journal article

AN - SCOPUS:85124041637

VL - 7

JO - Environmental Advances

JF - Environmental Advances

SN - 2666-7657

M1 - 100180

ER -