Page 6 - Application Notebook - PFAS Analysis

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

Experimental  Preparation of Samples

A surrogate spiking solution containing each
isotopically-labelled PFAS was added to all samples,
 List of PFAS Compounds and Preparation of including method blanks, duplicates, laboratory control
Calibration Standards
samples, matrix spikes and reporting limit checks. The
Table 2 lists all 49 PFAS compounds (30 targets and stock surrogate spiking solution was prepared at
19 isotopically-labeled surrogates) used in this study. 20 µg/L in 95:5% (vol/vol) acetonitrile (ACN):water.
The list covers the PFAS compounds named in ASTM Water samples (5 mL) were collected in 15 mL
D7979 method and includes additional compounds PP/HDPE centrifuge vials. Also, the blank (containing
listed for consideration in the appendix of the method. 5 mL of reagent water) and laboratory control sample
All PFAS standards were purchased from Wellington (containing the lowest calibration concentration for
Laboratories (Guelph, Ontario). each PFAS) were prepared for the study.

Stock standard solution at a concentration of 200 ng/L The samples (5 mL) were diluted 1:1 with methanol and
for all 49 compounds was prepared from the spiked with 40 µL of the surrogate spiking solution and
commercially available stock solutions. The stock vortexed for 2 minutes, resulting in a surrogate
standard solution was further diluted using a 50:50 concentration of 80 ng/L in the diluted solution. The
(vol:vol) methanol/water with 0.1% acetic acid to obtain samples were filtered and acetic acid (10 µL) was
the other eight calibration solutions; their final added to the filtrate to adjust the pH. The aliquots were
concentrations were at 150, 100, 80, 60, 40, 20, 10 and transferred to the LC vials for injection and analysis by
5 ng/L. These standards were not filtered. Calibration LC-MS/MS.
was performed using a 9-point curve, ranging from 5 –
200 ng/L. Due to the high method detection limit (MDL)
obtained for FHEA, FOEA and FDEA, the calibration  LCMS Analytical and Instrument Conditions
range for these compounds was adjusted to 100 – The analytical and instrument conditions are listed in
4000 ng/L and calibration standards were prepared as Table 3. Each PFAS standard was injected and
described above. analyzed separately to ensure positive identification
and maximum resolution. Upon collating the individual
The stock solutions were prepared and stored in PFAS- retention time and optimized MRM parameters, the
free polypropylene (PP) containers. Prior to the PFAS standard mixture (containing all PFAS
analysis, the solutions were shaken thoroughly then compounds) was prepared and used for subsequent
transferred to a 2 mL amber glass LC vial, and analysis. All compound parameters, including precursor
analyzed within 24 hours to achieve optimum results. In
the event that samples or standards are allowed to sit ion, product ion and collision energies, were optimized
in the LC vials, some PFAS compounds may settle, bypassing the analytical column using LabSolutions
precipitate or adsorb on the surface. To ensure a software. At least two MRM transitions were used.
homogenous solution and optimum results, it is Shimadzu UFMS, possessing an ultra-fast acquisition
necessary to vortex the solution prior to injection. rate of 555 MRM/sec and a high polarity switching
speed of 5 msec, is capable of MRM transitions with a
fast-enough cycle time to obtain high sensitivity with at

least ten data points over a peak. The target
compounds were identified by comparing the MRM
transitions of the sample to that of the standards. The

target analytes were quantitated using the quantifier
MRM transitions (Table 4) of the target compounds.
Concentrations were calculated using LabSolutions
software to generate a linear regression. The point of

origin was excluded, and a fit weighting of 1/x was used
to give more emphasis to the lower concentrations.