Determination of Pentachlorophenol in Sediment by Solid Phase Extraction Purification and Liquid Chromatography-Tandem Mass Spectrometry

In response to the issues of derivatization and long analysis time required for the determination of pentachlorophenol in sediment by gas chromatography-mass spectrometry, the method mentioned by the title was proposed. The sediment sample (2.00 g) was taken and placed into a 50 mL-polypropylene centrifuge tube with a cap, and 100 μL of 100 μg·L⁻¹¹³C₆-labeled pentachlorophenol isotope internal standard solution was added. The mixture was mixed evenly, and then extracted by vortex-mixing for 5 min with 10 mL of acetonitrile solution containing 1.0% (volume fraction) acetic acid, followed by ultrasonic extraction for 10 min and centrifugation for 5 min. This extraction procedure was repeated once. The combined supernatants were concentrated to 0.5 mL via rotary evaporation. The concentrate was reconstituted in 2 mL of 75% (volume fraction, the same below) acetonitrile solution and passed entirely through a Captiva EMR-Lipid cartridge. The cartridge was subsequently rinsed with 0.5 mL of 75% acetonitrile solution. All eluates were filtered through 0.22 μm needle polytetrafluoroethylene filter membrane. Pentachlorophenol was separated on Shim-pack Scepter C₁₈-120 column using a mixture of 5 mmol·L⁻¹ ammonium acetate solution and acetonitrile at different volume ratios as mobile phase for gradient elution. Mass spectrometric analysis was performed using electrospray ionization (ESI) in negative ion mode, operating in multiple reaction monitoring mode. As shown by the results, the linear range of standard curve of pentachlorophenol was 0.2−20.0 μg·L⁻¹, with detection limit (3S/N) of 0.03 μg·kg⁻¹. Test for recovery was made by the standard addition method, giving results in the range of 88.2%−116%, with RSDs of the determined values (n=6) less than 15%. This method was applied to the analysis of 18 actual sediment samples, and pentachlorophenol was detected in only one sample, with detection amount of 0.15 μg·kg⁻¹.