Presentation abstract
Scientific paper
Can determination of extractable organofluorine (EOF) be standardized? First interlaboratory comparisons of EOF and fluorine mass balance in sludge and water matrices
combustion ion chromatography
,
organic fluorine
,
perfluoroalkyl substances
,
polyfluoroalkyl substances
,
precursors
,
samples
The high proportion of unidentified extractable organofluorine (EOF) observed globally in humans and the environment indicates widespread occurrence of unknown per- and polyfluoroalkyl substances (PFAS). However, efforts to standardize or assess the reproducibility of EOF methods are currently lacking. Here we present the first EOF interlaboratory comparison in water and sludge. Three participants (four organizations) analyzed unfortified and PFAS-fortified ultrapure water, two unfortified groundwater samples, unfortified wastewater treatment plant effluent and sludge, and an unfortified groundwater extract. Participants adopted common sample handling strategies and target lists for EOF mass balance but used in-house combustion ion-chromatography (CIC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. EOF accuracy ranged from 85-101% and 76-109% for the 60 and 334 ng L-1 fluorine (F) - fortified water samples, respectively, with between-laboratory variation of 9-19%, and within-laboratory variation of 3-27%. In unfortified sludge and aqueous samples, between-laboratory variation ranged from 21-37%. The contribution from sum concentrations of 16 individual PFAS ( n-ary sumation PFAS-16) to EOF ranged from 2.2-60% but extended analysis showed that other targets were prevalent, in particular ultra-short-chain perfluoroalkyl acids (e.g. trifluoroacetic acid) in aqueous samples and perfluoroalkyl acid-precursors (e.g. polyfluoroalkyl phosphate diesters) in sludge. The EOF-CIC method demonstrated promising accuracy, robustness and reporting limits but poor extraction efficiency was observed for some targets (e.g. trifluoroacetic acid).
Scientific paper
Guide to Semi-Quantitative Non-Targeted Screening Using LC/ESI/HRMS
contaminants
,
decision making
,
electrospray-ionization
,
ion suppression
,
ionization
,
ionization efficiency scale
,
metabolomics data
,
mobile-phase
,
nts strategies
,
quantification
,
resolution-mass-spectrometry
,
system
,
waste-water
Non-targeted screening (NTS) with reversed phase liquid chromatography electrospray ionization high resolution mass spectrometry (LC/ESI/HRMS) is increasingly employed as an alternative to targeted analysis; however, it is not possible to quantify all compounds found in a sample with analytical standards. As an alternative, semi-quantification strategies are, or at least should be, used to estimate the concentrations of the unknown compounds before final decision making. All steps in the analytical chain, from sample preparation to ionization conditions and data processing can influence the signals obtained, and thus the estimated concentrations. Therefore, each step needs to be considered carefully. Generally, less is more when it comes to choosing sample preparation as well as chromatographic and ionization conditions in NTS. By combining the positive and negative ionization mode, the performance of NTS can be improved, since different compounds ionize better in one or the other mode. Furthermore, NTS gives opportunities for retrospective analysis. In this tutorial, strategies for semi-quantification are described, sources potentially decreasing the signals are identified and possibilities to improve NTS are discussed. Additionally, examples of retrospective analysis are presented. Finally, we present a checklist for carrying out semi-quantitative NTS.
Scientific paper
Non-target screening for characterization of chemicals in human ovarian follicular fluid
Scientific paper
Suspect and non-target screening of ovarian follicular fluid and serum – identification of anthropogenic chemicals and investigation of their association to fertility
bisphenol-a concentrations
,
contaminants
,
embryo score
,
exposure
,
infertility
,
mass spectrometry
,
perfluorinated chemicals
,
perfluoroalkyl
,
polychlorinated biphenyls
,
women
In this work, ultra-high performance liquid chromatography-high resolution (Orbitrap) mass spectrometry-based suspect and non-target screening was applied to follicular fluid (n = 161) and serum (n = 116) from women undergoing in vitro fertilization in order to identify substances that may be associated with decreased fertility. Detected features were prioritized for identification based on (i) hazard/exposure scores in a database of chemicals on the Swedish market and an in-house database on per- and polyfluoroalkyl substances (PFAS); (ii) enrichment in follicular fluid relative to serum; and (iii) association with treatment outcomes. Non-target screening detected 20 644 features in follicular fluid and 13 740 in serum. Two hundred and sixty-two features accumulated in follicular fluid (follicular fluid: serum ratio >20) and another 252 features were associated with embryo quality. Standards were used to confirm the identities of 21 compounds, including 11 PFAS. 6-Hydroxyindole was associated with lower embryo quality and 4-aminophenol was associated with higher embryo quality. Overall, we show the complexity of follicular fluid and the applicability of suspect and non-target screening for discovering both anthropogenic and endogenous substances, which may play a role in fertility in women.
Scientific paper
High Concentrations of Unidentified Extractable Organofluorine Observed in Blubber from a Greenland Killer Whale (Orcinus orca)
It is generally accepted that per- and polyfluoroalkyl substances (PFASs) occur primarily in protein-rich tissues such as blood and liver, but few studies have examined the occurrence of legacy and novel PFASs in lipid-rich tissues such as blubber. Here we report the distribution of 24 PFASs, total fluorine, and extractable organic fluorine (EOF) in eight different tissues of a killer whale (Orcinus orca) from East Greenland. The sum of target PFAS concentrations was highest in liver (352 ng/g of wet weight) and decreased in the following order: blood > kidney ≈ lung ≈ ovary > skin ≈ muscle ≈ blubber. Most of the EOF consisted of known PFASs in all tissues except blubber, which displayed the highest concentration of EOF, almost none of which was attributed to targeted PFASs. Suspect screening using high-resolution mass spectrometry revealed the presence of additional PFASs but is unlikely to explain the high concentrations of EOF in blubber. While the identity of this unknown organofluorine and its pervasiveness in marine mammals require further investigation, this work suggests that exposure of killer whales to organofluorine substances may be underestimated by determination of legacy PFASs exclusively in liver or blood.
Scientific paper
Fluorine Mass Balance and Suspect Screening in Marine Mammals from the Northern Hemisphere
There is increasing evidence that the ~20 routinely monitored per- and polyfluoroalkyl substances (PFASs) account for only a fraction of extractable organofluorine (EOF) occurring in the environment. To assess whether PFAS exposure is being underestimated in marine mammals from the Northern Hemisphere, we performed a fluorine mass balance on liver tissues from 11 different species using a combination of targeted PFAS analysis, EOF and total fluorine determination, and suspect screening. Samples were obtained from the east coast United States (US), west and east coast of Greenland, Iceland, and Sweden from 2000-2017. Of the 36 target PFASs, perfluorooctane sulfonate (PFOS) dominated in all but one Icelandic and three US samples, where the 7:3 fluorotelomer carboxylic acid (7:3 FTCA) was prevalent. This is the first report of 7:3 FTCA in polar bears (~1000 ng/g, ww) and cetaceans (<6-190 ng/g, ww). In 18 out of 25 samples, EOF was not significantly greater than fluorine concentrations derived from sum target PFASs. For the remaining 7 samples (mostly from the US east coast), 30-75% of the EOF was unidentified. Suspect screening revealed an additional 33 PFASs (not included in the targeted analysis) bringing the total to 59 detected PFASs from 12 different classes. Overall, these results highlight the importance of a multi-platform approach for accurately characterizing PFAS exposure in marine mammals.
Scientific paper
Temporal trends of suspect- and target-per/polyfluoroalkyl substances (PFAS), extractable organic fluorine (EOF) and total fluorine (TF) in pooled serum from first-time mothers in Uppsala, Sweden, 1996-2017
A combined method for quantitative analysis, along with suspect and non-target screening of per- and polyfluoroalkyl substances (PFAS) was developed using ultra-high pressure liquid chromatography-ultra-high resolution (Orbitrap) mass spectrometry. The method was applied together with measurements of total- and extractable organofluorine (TF and EOF, respectively), to pooled serum samples from 1996-2017 from first-time mothers living in the county of Uppsala, Sweden, some of which (i.e.148 of 472 women sampled 1996-2012) were exposed to drinking water contaminated with perfluorohexane sulfonate (PFHxS) and other PFAS until mid-2012. Declining trends were observed for all target PFAS as well as TF, with homologue-dependent differences in year of onset of decline. Only 33% of samples displayed detectable EOF, and amongst these samples the percentage of EOF explained by target PFAS declined significantly (-3.5% per year) over the entire study period. This finding corroborates prior observations in Germany after the year 2000, and may reflect increasing exposure to novel PFAS which have not yet been identified. Suspect screening revealed the presence of perfluoro-4-ethylcyclohexanesulfonate (PFECHS), which displayed declining trends since the year 2000. Non-target time trend screening revealed 3 unidentified features with time trends matching PFHxS. These features require further investigation, but may represent contaminants which co-occurred with PFHxS in the contaminated drinking water.
