PFAS in Drinking Water, Food, and Environmental samples by Online SPE-LC-MS/MS

An estimated 4700 chemical compounds are classified as PFAS. 20 of these have been targeted in the EU Drinking Water Directive 2020/2184 due to their toxicity. They are strongly suspected of causing liver damage, thyroid disease, adiposity, fertility disorders, and cancer. 

PFAS in Drinking Water: Online SPE-LC-MS/MS Method in Accordance with DIN 38407-42 

The EU Drinking Water Directive (EU 2020/2184) includes maximum limits for total PFAS of 0.5 µg/L. For the sum of 20 PFAS of most concern the maximum limit is 0.1 µg/L, which requires a limit of detection of (LOD) of 30 ng/L for the sum and 1.5 ng/L for the individual compounds. Even when using a modern triple quadrupole HPLC-MS system, a concentration step is required.

A GERSTEL MultiPurpose Sampler (MPS) and GERSTEL SPExos Online-SPE coupled directly to an LC-MS/MS system can determine PFAS at the required levels by direct injection of water samples. The system is fully automated. Solid phase extraction (SPE) is used as specified in the DIN 38407-42 method. The DIN method list of analytes can easily be expanded to include those in the EU Drinking Water Directive. Key benefits are simplified sample handling, very low solvent consumption, and excellent accuracy and reproducibility. Successful participation in a round robin demonstrates the high quality of results achieved: “RV 7/22 PFAS nach EU-TrinkwasserRichtlinie“ (RV 7/22 PFAS in accordance with the EU Drinking Water Directive). The certificate can be found here.

Due to the anionic properties of the analytes to be determined, weak anion exchange (WAX) resins are used. Following analyte concentration, the SPE cartridges are rinsed with solvent and eluted with a solution of ammonia in methanol resulting in analyte focusing on the column head for improved LC separation and MS/MS detection. The SPE cartridge can be replaced after each analysis to eliminate carryover.

Repeated rinse cycles with the rinse solutions added through the sample vial result in the transfer of fine sediment particles to the SPE cartridge where adsorbed PFAS compounds are desorbed and included in the analysis. Even solid sample extracts can be cleaned using the online SPE system after diluting an aliquot of the extract with water inside the syringe. After injection, the syringe is rinsed with solvents and solutions, which are injected to the system after each rinse cycle, eliminating loss through adsorption. The workflow meets the requirements of the DIN 38414-14 method for Determination of selected polyfluorinated compounds (PFC) in sludge, compost, and soil.

PFAS in Food: Online SPE-LC-MS/MS Method with extract cleanup. 

PFAS in food can be determined by LC-MS after a QuEChERS-like extraction. The automated online SPE-LC-MS/MS system from GERSTEL combines extract cleanup and PFAS determination. Examples are meat, fish, and egg. The use of weak ion exchangers (WAX) allows the cartridges to be washed with organic solvents. This further improves the cleanup and significantly reduces matrix effects for improved accuracy, reproducibility, and limits of determination. A large volume of extract can be injected onto the replaceable SPExos cartridge, further lowering the limits of quantification. Compared to a classic SPE, the online SPE offers the advantages of simplified sample handling, very low solvent consumption, and good accuracy and precision.

PFAS in Air: High Volume Sampling and Determination using Thermal Desorption and GC-MS/MS

In a three-year collaborations, GERSTEL together with Eurofins Air Toxics, Agilent Technologies, and CAMSCO have developed a complete method for the analysis of volatile PFAS compounds in indoor air and other atmospheres. 
This method uses a Teflon-free thermal desorption system with gas chromatography and tandem mass spectrometry to analyze very high-volume air samples, 300 Liters or more, while suppressing the high background created by such large samples
Along the way, we saw some things that were beyond what experienced gas chromatographers would consider ‘normal’.  PFAS species, although often having molecular weights in the 400 to 700 amu range, behave like very small molecules in the 50 to 100 amu range.

PFAS Online Seminars 2023


PFAS Online Seminars 2022