Ultra Low-Level Detection of Perfluoroalkyl Substances (PFASs)

In this technology brief, we describe the detection of routinely monitored PFASs that was performed on the ACQUITY UPLC I-Class System and Xevo TQ-S. Special considerations for the I-Class with flow through needle (FTN) hardware are also detailed.

Benefits

The PFC Analysis Kit can be implemented on the  ACQUITY UPLC I-Class System and Xevo TQ-S to achieve ultra-sensitive detection of routinely monitored PFASs.

Perfluoroalkyl substances (PFASs) encompass a range of fully fluorinated alkyl compounds, typically with an anionic end group. Previously described as perfluoroalkyl compounds (PFCs), they have been implemented in a range of consumer goods and industrial processes due to their  hydro- and lipophobic properties.  

As a result of their widespread use and subsequent leaching from materials, they have been found in various environmental and biological samples. PFASs are also ubiquitous in the laboratory environment, namely in Teflon components used in analytical equipment. Waters PFC Analysis Kit (part no. 176001744) specifically addresses this challenge. The kit is comprised of PFAS-free components to ensure a clean system, a sample preparation protocol, along with standards, columns, vials and caps.  

Alterations to existing ACQUITY UPLC systems can easily be performed. Although minor variations exist in the solvent line configurations across the ACQUITY UPLC models, the PFC Analysis Kit can be easily implemented across all models. In this technology brief,  we describe the detection of various routinely monitored PFASs that was performed on the ACQUITY UPLC I-Class System and Xevo TQ-S. Special considerations for the I-Class with flow through needle (FTN) hardware are also detailed.

The LC analysis was performed on an  ACQUITY UPLC I-Class System. Pre-cut PEEK tubing from the PFC Analysis Kit were used to replace all of the Teflon solvent lines, per the kit instructions. The side panel of the I-Class sample manager was removed in order to replace the sample manager wash line, as shown in Figure 1; all of the other solvent lines changed  are affixed in the BSM. The use of the  ACQUITY BEH C₁₈ Isolator Column and pre-cut stainless steel tubing provided in the kit further ensured that PFAS contamination was retained prior to injection of the sample. The LC method employed an ACQUITY BEH C₁₈ (50 x 2.1 mm, 1.7 µm) Column, with the gradient described in Table 1a. Standards provided in the PFC Kit were used to create the dilution series, covering a range of three orders of magnitude. The Xevo TQ-S showed exceptional sensitivity for the analytes, with their respective MRMs and optimized instrumental parameters summarized in Table 1b. 

Measured limits of detection (based on peak-to-peak, signal-to-noise measurements of 1:3) for the analytes were below 0.07 ng/mL in solvent standards. In the case of the most commonly monitored PFAS  analyte, perfluorooctanesulfonate (PFOS), the limit of detection was 0.0125 ng/mL (Figure 2). These low limits of detection  highlight the notable sensitivity of this platform for PFASs analysis. 

Accurate and highly sensitive PFASs analysis can be achieved using the PFC Analysis Kit, which is adaptable to any ACQUITY UPLC system. A complete analytical solution for the PFASs is presented, particularly  when used in combination with the Xevo TQ-S for ultra low-level detection.