key: cord-0951182-7mkrdcju
authors: Bowers, Isaac; Subedi, Bikram
title: Isoprostanes in Wastewater as Biomarkers of Oxidative Stress During COVID-19 Pandemic
date: 2021-01-03
journal: Chemosphere
DOI: 10.1016/j.chemosphere.2020.129489
sha: f27ced593ad3a395949e9f459b38e3f429e7273c
doc_id: 951182
cord_uid: 7mkrdcju

Isoprostanes are the potential biomarkers of endogenous human metabolism and proven clinically to provide the quantitative measure of systematic oxidative injury. An ultra-performance liquid chromatography-tandem mass spectrometric analytical method capable of determining four biomarkers of oxidative stress (8-iso-PGF2α, 2,3-dinor-iPF2α-III, PGE2, and 5-iPF2α-VI) in wastewater was developed and validated. Isoprostanes were quantified in the range of 31.1 to 1270 ng/L in raw wastewater samples in two communities in western Kentucky and Tennessee during the first four months of the COVID-19 pandemic. Consistent detection of PGE2 and 5-iPF2α-VI in wastewater suggested that PGE2 and 5-iPF2α-VI can be a reliable biomarker of community oxidative anxiety. The higher 4-month average mass load of isoprostanes [(ranged from 22.9 mg/d/1000 people to 807 mg/d/1000 people] may be attributed to the elevated community level oxidative anxiety owing COVID-19 uncertainties. The average mass loads of PGE2 and 5-iPF2α-VI in a community were significantly increased (two-tailed p <0.001) from the first month of COVID-19 pandemic to the second month; however, significantly decreased (two-tailed p <0.001) in the third month. Wastewater-based-epidemiological determination of isoprostanes can be a near-real-time and cost-effective approach of a trend in community depression. This is the first report of the quantification of PGE2 and 5-iPF2α-VI in wastewater and estimation of the community level oxidative anxiety.

) were used to separate analytes using an ACQUITY UPLC ® Oligonucleotide 142 BEH C18 column (150 mm× 2.1 mm i.d. × 1.7 μm particle size). Target analyte's peak 143 identification was based on the relative retention time (±0.05 min) to their standard solution, two multiple reaction monitoring (MRM) transitions (Table 1) in the negative mode of ionization, 145 and the ratio of the abundance of quantitative to qualitative ions (±20%). The gas temperature, 146 sheath gas temperature, and capillary voltage were optimized to 350°C, 300°C, and 4000 V, 147 respectively..

The isotopic dilution mass spectrometry method was applied where a known quantity of recoveries of 8-iso-PGF2α, 2,3-dinor-iPF2α-III, PGE2, and 5-iPF2α-VI were 99 ± 30.4%, 64 ± 182 11.9%, 58 ± 5.7%, and 126 ± 6.2%, respectively (Table 1) . However, MCX cartridge extraction 183 of isoprostanes resulted in the extraction recoveries range from 71.2% (PGE2) to 169% (8-iso-184 PGF2α). Due to the unacceptable recovery of 8-iso-PGF2α, HLB cartridges were considered for 185 further extraction of isoprostanes from raw wastewater.

The intraday repeatability of wastewater extracts spiked at 25 ng and 125 ng levels were 187 determined by analyzing ten consecutive runs. The intraday precision ranged from ±1.1 (PGE2) to ±20.0 (8-iso-PGF2α) at 25 ng level and from ±1.4 (2,3-dinor-iPF2α-III) to ±4.8 (5-iPF2α-VI at 189 125 ng level (Table 1) . 190 The limit of detection (LOD) and limit of quantitation (LOQ) were calculated in 191 wastewater using the minimum target isoprostane concentration that results in a signal to noise 192 ratio of 3 and 10, respectively. LOD ranged from 8.8 ng/L (5-iPF2α-VI) to 25.6 ng/L (2,3-dinor-193 iPF2α-III) and LOQ ranged from 29.5 ng/L (5-iPF2α-VI) to 85.5 ng/L (2,3-dinor-iPF2α-III) 194 ( Table 1 ). Data points that fell below LOQ were adjusted by substituting them with their 195 respective ½ LOQ values when 70% of the data from that sampling period were above their 196 LOQ.

As part of quality assurance and quality control, a randomly selected sample was spiked 198 (matrix spike, n=2) with 125 ng of each target isoprostanes and their corresponding internal 199 standards. The average relative recoveries of isoprostanes ranged from 71.9±1.0% (8-iso-PGF2α) 200 to 128±9% (2,3-dinor-iPF2α-III) ( Table 1) . A calibration standard mixture was considered as a 201 continuing calibration verification (CCV) solution and analyzed before and after each set of ten 202 samples. The average percent recoveries for all target isoprostanes were within ±20% (Table 1) . 12S1, S17-S21.

Four oxidative stress hormones were determined in wastewater 2. PGE2 and 5-iPF2α-VI can be a reliable biomarker of community oxidative anxiety 3. Average mass load of isoprostanes ranged from 22.9 to 807 mg/d/1000 people 4. Mass load of isoprostanes increased from the first to second month

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☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:J o u r n a l P r e -p r o o f