BIOTECH & LIFE SCIENCES
C1-C10 PFAS biomonitoring
Restek’s Shun-Hsin Liang (PhD) provides a more comprehensive understanding of how ultra-short chain PFAS can be integrated into biomonitoring methods
INTRODUCTION While concerns about adverse human health effects from long-chain per- and polyfluoroalkyl substances (PFAS) have led to increased biomonitoring, less is known about the potential toxicity of ultrashort-chain PFAS, which are ubiquitous and can occur at very high levels. Since both human plasma and serum are widely used for biomonitoring longer-chain PFAS, developing methods that include shorter chain PFAS are critical to gaining a more comprehensive understanding of PFAS exposure and human health. The workflow presented here was developed for the simultaneous analysis of C1 to C10 perfluoroalkyl carboxylic and sulfonic acids, along with four alternative PFAS, in human plasma and serum.
EXPERIMENTAL PFAS-free human plasma and serum were not found during screening tests, so charcoal-stripped fetal bovine serum (FBS) was used as the blank matrix for method verification because it did not contain any of
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the target analytes, except TFA. To confirm the method’s suitability for real-world samples, NIST SRM 1950 (human plasma) and NIST SRM 1957 (human serum), which contain known concentrations of short-chain and long-chain PFAS, were also tested. Both SRMs contained PFOA, PFNA, PFDA, PFHxS, and PFOS; and NIST SRM 1957 also contained PFHpA. Calibration standards were prepared in reverse osmosis (RO) purified water with 1x phosphate-buffered saline (PBS) added to better match the sample matrices. RO water (generated at Restek) was used to prepare the standards and mobile phases because our testing revealed that it was devoid of PFAS contamination, except for barely detectable TFA. To assess accuracy and precision,
FBS was fortified at 0.4, 2, 10, and 30 ppb with non-labeled PFAS and isotopically labeled 13
C-TFA,
which served as a surrogate for the determination of TFA recovery. The fortified FBS samples were mixed with a quantitative internal standard (QIS) working solution containing
five isotopically labeled PFAS and an extracted internal standard (EIS) working solution. A single-step protein precipitation was performed in clean polypropylene HPLC vials to minimise background PFAS contamination. The NIST SRMs were prepared using the same procedure. Gradient LC-MS/MS analysis
was performed using an Ultra IBD analytical column (3 µm; 100 mm x 2.1 mm; cat.# 9175312) because its polar- embedded stationary phase provides strong retention of polar compounds, even in the presence of the various salts, electrolytes, and buffers that are inherently found in plasma and serum. A PFAS delay column (cat.# 27854) was installed between the pump mixer and the injector to prevent coelution of any instrument-related PFAS with target analytes in the sample. Complete sample preparation and analytical method details, as well as additional discussion, are available in the full application note, which can be accessed at
www.restek.com by entering ‘CFAN4273-UNV’ in the Resources Hub search.
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