For PFHS and PFNA (Figure 1C, D), the highest population median concentrations were observed in children.
Smaller but still substantial differences were also observed for PFHS [57.
Larger correlations were observed between PFHpA and PFOA (~ 40%), PFHS and PFOS (~ 50%), PFOS and PFNA (~ 50%), and PFNA and PFDA (~ 60%).
Samples for PFHS and PFOS were analyzed separately from PFOA samples.
The internal standard for PFOS and PFHS analyses was a labeled perfluorooctanesulfonate ([.
For PFOS and PFHS, we used 80 and 350 ng/mL targeted mean spiked samples.
Method accuracy for serum analysis against plasma calibration was expanded to [+ or -] 19% for PFOA, [+ or -] 21% for PFOSAA, and [+ or -] 26% for PFHS.
The instrument was operated in the multiple reaction monitoring mode under optimized conditions for the PFOS, PFOA, PFHS, PFOSAA, PFOSA, M556, and M570 detection of the negative ions formed by TurboIonSpray ionization (Applied Biosystems, Foster City, CA).
Median concentrations of PFOS and PFHS were statistically significantly (p < 0.
the lower end of the second quartile and the upper end of the third quartile), number of samples < LLOQ, 90th percentile, median, geometric mean, and 95% confidence interval (CI) of the geometric mean for PFOS, PFOA, PFHS, PFOSAA, and M570 are provided in Table 1.
Serum samples from males also had significantly higher serum levels of PFOA and PFHS compared with serum samples from females, although the mean levels for both sexes were approximately one order of magnitude lower than that of PFOS.
The remaining scatter plots display the correlations between PFOS and PFHS (r = 0.