Page 11 - Application Notebook - PFAS Analysis

SHIMADZU | WHITE PAPER Ultra-fast LC-MS/MS Analysis of PFAS in Environmental Waters

 PFAS Stability Study – Effects of Solvents, LC  Calibration Range and Method Detection Limit
Vial Materials and Vortex (MDL)
The shelf life of the prepared PFAS standards was Calibration was performed for all PFAS compounds
evaluated using the following solvents: 10%, 30%, using a nine-point calibration curve, ranging from
50%, 70% and 90% methanol, in both glass and 5 ng/L – 200 ng/L with some exceptions. FHEA, FOEA
polypropylene vials. The plots of relative intensity of and FDEA, the fluorotelomer acids, were calibrated in
PFAS against shelf life (time/hours) shown in Figure 3 the range of 100 – 4000 ng/L. The linearity of the
demonstrate that the 50% methanol in water used in curves was evaluated using 1/x weighting, ignoring the
the ASTM methods sufficiently dissolves the PFAS origin. The calibration range are shown in Table 4 and
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compounds and keeps them in solution. The lower all calibration curves had a regression coefficient (R )
concentrations of methanol (10% and 30% methanol) higher than 0.99. The calibration curves and regression
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show significant loss of PFAS due to the insolubility of coefficient (R ) of some selected PFAS compounds are
PFAS in the solvent used. The recovery results for 90% illustrated in Figure 5.
methanol are similar to that of 70% methanol.
A MDL study was conducted by spiking the water
Furthermore, the materials of the LC vial, amber glass samples (5 mL). FHEA, FOEA and FDEA were spiked
and polypropylene, were investigated to determine the at a concentration of 100 ng/L; the rest of the PFAS
potential adsorption of PFAS on the vial surface Similar compounds were spiked at 20 ng/L. The
recovery and quantitation were observed regardless of MDL, %recovery and % RSD were determined and are
the material of the LC vials. Rather than the material of shown in Table 4. The MDLs using the LCMS-8060 are
the LC vial, the effect of vortex on the recovery of in the range of 0.6 – 5.4 ng/L for the 44 PFAS
PFAS is considerable (Figure 4). To demonstrate the compounds (excluding fluorinated telomer acids).
importance of utilizing the vortex mixer, a PFAS Similarly, the % recovery and % RSD for these 44
standard solution was allowed to sit for 24 hours. An PFAS were within the acceptable limits (70-130%).
end mid-level calibration check (50 ng/L) was prepared
and the recovery of the PFAS compounds from the vial,
before and after mixing, was determined. Figure 4  Summary and Conclusion
shows the chromatogram of the PFAS compounds This white paper summarized and illustrated the use,
before and after vortex. The recovery of the long-chain performance and compatibility of Shimadzu UFMS for
PFAS is noticeably lower before vortex. The use of the analysis of PFAS in environmental samples. With
vortex ensures that the solution is homogenous and reference to ASTM D7979, 49 PFAS compounds were
consistent results are obtained. separated and quantified with a simple direct injection
The PFAS concentration in the vial may change after method and rapid LC-MS/MS analysis (LCMS-8060).
the vial cap is pierced as the organic solvent (i.e. Direct injection without SPE allows for maximum
methanol:water solution) and/or PFAS compound can throughput and minimal background, loss and
be lost through the puncture. If calibration standards contamination cause by sample preparation. The high-
are to be used multiple times, it is recommended to use speed and high-sensitivity characteristics of the LCMS-
amber glass vial with sealed replaceable caps. This 8060 achieve a method detection limit of 0.6 – 5.4 ng/L
sealing of vials immediately after injection may alleviate and recovery of 84 – 113% for all PFAS compounds,
the loss of PFAS. excluding FTAs. These results fall within the quality
control requirements and limits. Together with a high
scanning speed and a short dwell time, the Shimadzu
LCMS-8060 achieves rapid, reliable and highly
sensitive quantitation of PFAS in environmental waters.