Semiquantitation of suspect per-and polyfluoroalkyl substances (PFAS) in complex mixtures is challenging due to the increasing number of suspect PFAS. Traditional 1:1 matching strategies require selecting calibrants (target−surrogate standard pairs) based on head group, fluorinated chain length, and retention time, which is time-consuming and requires expert knowledge. Lack of uniformity in calibrant selection for estimating suspect concentrations among different laboratories makes comparing reported suspect concentrations difficult. In this study, a practical approach whereby the area counts for 50 anionic and 5 zwitterionic/cationic target PFAS were ratioed to the average area of their respective stable-isotope labeled surrogates to create "average PFAS calibration curves" for suspects detected in negative-and positive-ionization mode liquid chromatography quadrupole time-of-flight mass spectrometry. The calibration curves were fitted with log−log and weighted linear regression models. The two models were evaluated for their accuracy and prediction interval in predicting the target PFAS concentrations. The average PFAS calibration curves were then used to estimate the suspect PFAS concentration in a well-characterized aqueous film-forming foam. Weighted linear regression resulted in more target PFAS that fell within 70−130% of their known standard value and narrower prediction intervals than the log−log transformation approach. The summed suspect PFAS concentrations calculated by weighted linear regression and log−log transformation were within 8 and 16% of those estimated by a 1:1 matching strategy. The average PFAS calibration curve can be easily expanded and can be applied to any suspect PFAS even if the confidence in the suspect structure is low or unknown.
Individual animals in natural populations tend to host diverse parasite species concurrently over their lifetimes. In free‐living ecological communities, organismal life histories shape interactions with their environment, which ultimately forms the basis of ecological succession. However, the structure and dynamics of mammalian parasite communities have not been contextualized in terms of primary ecological succession, in part because few datasets track occupancy and abundance of multiple parasites in wild hosts starting at birth. Here, we studied community dynamics of 12 subtypes of protozoan microparasites (Theileria spp.) in a herd of African buffalo. We show that Theileria communities followed predictable patterns of succession underpinned by four different parasite life history strategies. However, in contrast to many free‐living communities, network complexity decreased with host age. Examining parasite communities through the lens of succession may better inform the effect of complex within host eco‐evolutionary dynamics on infection outcomes, including parasite co‐existence through the lifetime of the host.
In free-living ecological communities, organismal life histories shape
interactions with their environment, which ultimately forms the basis of
ecological succession. Individual animals in natural populations tend to
host diverse parasite species concurrently over their lifetimes.
However, the structure and dynamics of mammalian parasite communities
have not been contextualized in terms of primary ecological succession,
in part because few datasets track occupancy and abundance of multiple
parasites in wild hosts starting at birth. Here, we studied community
dynamics of twelve subtypes of protozoan microparasites (Theileria spp.)
in a herd of African buffalo. We show that Theileria communities
followed predictable patterns of succession underpinned by four
different parasite life-history strategies. In contrast to many
free-living communities, network complexity decreased with host age.
Examining parasite communities through the lens of succession may better
inform the effect of complex within host eco-evolutionary dynamics on
infection outcomes, including parasite co-existence through the lifetime
of the host.
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