Biotage has produced an application note describing an effective method for the extraction of polyfluorinated compounds in water using EVOLUTE® EXPRESS WAX SPE prior to LC-MS/MS analysis.
Introduction
Polyfluorinated compounds (PFCs) such as PFOS (perfluorooctanesulfonic acid) and PFOA perfluorooctanoic acid) are man-made fluorosurfactants. Due to their widespread industrial use and chemical stability, they have become ubiquitous in the natural environment. Exposure to PFCs has been linked to cancer, endocrine disruption and developmental delays.
Sample Preparation Procedure
Analytes were prepared at a concentration of 50 pg μL-1 in 18.2 MΩ cm water and stored at approximately 4 °C prior to use. A 20 μL aliquot of this solution was diluted to 1 L in 18.2 MΩ cm water to give a spiked concentration of
1 ng L-1. No internal standards were used in this method.
Method Evaluation
Method linearity was determined by spiking known amounts of PFCs into 18.2 MΩ cm water. Calibration lines were constructed by spiking 100 μL of PFC stocks at variable concentrations into 250 mL 18.2 MΩ cm water giving final concentrations of 0.1, 0.5, 2, 4 and 5 ng L-1. The samples were extracted in duplicate using the method detailed above to give duplicate calibration curves. A 1/x weighting was applied and the regression coefficient (r) was determined using Analyst software.
Results
The extracted ion chromatograms demonstrate good chromatography at 1 ng L-1 from a spiked extraction of 100 mL 18.2 MΩ cm water. The analytes demonstrate acceptable linearity over the calibrated range of 0.1 ng L-1 to 5 ng L-1 as demonstrated by the calibration curves in the application note.
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