abstract

Abstract

Per- and polyfluorinated alkyl substances (PFAS) are a group of manmade chemicals that are known to enter the water supply and bioaccumulate in watershed ecosystems. Hence, the US EPA published the fifth unregulated contaminant monitoring rule (UCMR5)5, which proposes maximum residue limits (MRL) for PFAS residues in EPA method 533. A method has been developed here using solid phase extraction (SPE) and the SCIEX Triple Quad 4500 system monitoring 22 different PFAS species. Observed sensitivity and reproducibility meets the UCMR5 requirements for EPA method 533 compounds.

introduction

Introduction

Per- and polyfluorinated alkyl substances (PFAS) are a group of manmade chemicals that have been used for decades in a large host of applications.  A recent review focused on 1,400 unique PFAS species¹ although current OECD databases have upwards of 4,500 unique PFAS compounds.² The resilience of some PFAS to degradation and their potential for biological harm have spurred health and environmental concerns amongst regulatory agencies.  The CDC’s national biomonitoring program has found evidence of widespread presence of certain PFAS residues in human serum³.  One possible route of human exposure is from PFAS contaminated water.⁴

PFAS are known to enter the water supply and bioaccumulate in watershed ecosystems. This can be a health issue for humans who directly consume contaminated water.  The US EPA published the fifth unregulated contaminant monitoring rule (UCMR5)⁵, which proposes maximum residue limits (MRL) for PFAS residues in EPA method 533.  Representative chemical structures are shown in Figure 1.

This technical note presents data collected in accordance with EPA method 533 requirements for the initial demonstration of capability (IDC). Sample preparation was done using Phenomenex Strata-X-AW Weak Anion solid-phase extraction (SPE) and data acquisition was performed using the SCIEX Triple Quad 4500 system coupled to an ExionLC AC system.

The MRL is verified for a given concentration when 50% ≤ PIR ≤ 150%.  MRLs verified here met or exceeded UCMR5 reporting criteria (Table 1).  Figure 4 illustrates representative analyte chromatograms at their found MRL values.

Figure 1. Representative structural diversity among EPA method 533 analytes. Compounds can have either sulfonate (left) or carboxylate head groups (right).  Structure variability can also include per-/polyfluorinated species, the presence or absence of ether linkage(s) and alkyl chain length with or without branching.

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Key method features

• MRLs ≤ 3 ng/L reported for all analytes, meeting UCMR5 requirements for EPA method 533 compounds
• Sensitive and robust performance meets all EPA method 533 performance criteria
• SCIEX OS software simplifies data review and report generation using custom calculations and flagging rules
• Specialized LC setup ensures low systemic contamination.