Determination of 31 perfluoroalkyl and polyfluoroalkyl substances in water by ultra performance liquid chromatography-triple quadrupole mass spectrometry combined with direct injection

²>0.994） across a defined concentration range. The limits of detection （LODs） and quantification （LOQs） were 0.007 1-3.0 ng/L and 0.024-10 ng/L， respectively. Recoveries at spiked levels of 2， 10， and 500 ng/L ranged from 67.2% to 130.2%， with relative standard deviations （RSDs） of 0.30% to 18%. To quantify the effective equivalence between the enrichment efficiency of SPE and the sensitivity of direct injection methods， a comparative analysis of analyte recovery rates was performed for both approaches. Furthermore， for long-chain PFAS， direct injection demonstrated consistent and favorable recovery performance. The method was applied to analyze PFAS in groundwater samples. The results showed that 24 PFAS were detectable with the total PFAS content （∑PFAS） ranging from 20.6 to 521 ng/L， with perfluorooctanoic acid （PFOA） and perfluorobutanoic acid （PFBA） being the primary pollutants. This approach is simple， rapid， highly sensitive， and provides broad coverage of target analytes， making it suitable for the quantitative analysis of PFAS in urban groundwater. It offers an efficient and reliable technical solution for determining trace-level PFAS in environmental water samples.