Page 63 - Application Notebook - PFAS Analysis

No. SSI-LCMS-120

Liquid Chromatography Mass Spectrometry

Mass Spectrometry
Analysis and Quantitation of Per- and

Polyfluorinated Alkyl Substances (PFAS) in EPA

No. LCMS-120 Method 537.1 Using High Resolution Accurate

■ Introduction
EPA Method 537 was expanded to EPA Method Table 1: LC parameters

537.1 in November 2018 to include four new per- LC System Nexera-X2 UHPLC System
and polyfluoroalkyl substances (PFAS). While EPA Shim-pack Velox ,
TM
Method 537.1 focuses on well-known PFAS, such as Analytical Column 150mm x 2.1mm x 2.7µm,
PFOA, PFOS, and GenX , there are thousands of Part No. 227-320094-04
1
unknown PFAS that can potentially contaminate Solvent Delay Column Shim-pack XR-ODS
50mm x 2mm x 2.2µm,
drinking water. Analysis of unknown contaminants Part No. 228-41605-93
requires high resolution and accurate mass Column Temp. 40 C
o
capabilities in order to positively identify the Injection Volume 5 µL
molecular formula. This work demonstrates that the Mobile Phase A: 20 mM Ammonium Acetate
quantitation of all PFAS outlined in EPA Method B: Methanol
537.1 can be performed on a quadrupole time-of- Flow Rate 0.25 mL/min
flight mass spectrometer (QTOF) at low parts per Run Time 35 minutes
trillion concentrations in environmental drinking Table 2: LCMS parameters
water samples. Quantitation limits on the QTOF are
compared to a triple quadrupole mass spectrometer MS Instrument LCMS-8045 and LCMS-9030
(QQQ). Additionally, the workflow to tentatively Interface Electrospray Ionization (ESI)
Negative mode
identify untargeted PFAS is also included. Interface Temp. 100 C
o
Desolvation Line o
■ Methods Temp. 100 C
o
Electrospray source conditions were optimized on a Heat Block Temp. 200 C
QQQ (Shimadzu LCMS-8045) and applied to the Heating Gas Flow 15 L/min
QTOF (Shimadzu LCMS-9030). MRM transitions were Drying Gas Flow 5 L/min
determined on a QQQ, and accurate mass Nebulizing Gas Flow 3 L/min
Total MRMs
48
precursor/product ions were determined on a QTOF.
The chromatographic parameters are based on the ■ Qualitative Analysis
chromatographic method used in EPA Method The overall workflow for identifying unknown PFAS
537.1. A Shim-pack XR-ODS 50 x 3.0 mm column in environmental samples can be broken down into
was used as a delay column, and a Shim-pack four steps. One representative ion was chosen to
TM
Velox 150 mm x 2.1 mm x 2.7 µm column was used outline the workflow for tentatively identifying an
as the analytical column. Quantitation was unknown compound using Insight Explore.
performed using MRM on the QQQ and high-
resolution MRM on the QTOF. Detailed information
of the method conditions is included in Tables 1 and
2.