A new and sensitive liquid chromatography/electrospray-tandem mass spectrometric (LC/ESI–MS/MS)method for the determination of 12 perfluorinated compounds (PFCs) in cow milk is described. Milksamples were extracted with acetone and cleaned-up by a graphitized carbon black solid-phase extrac-tion cartridge, optimizing the entire procedure by using a screening experimental design. LC/ESI–MS/MSwas performed in negative ion mode using multiple reaction monitoring mode. The performance of themethod was evaluated under the optimized conditions in terms of matrix effects, range of linearity, accu-racy, and repeatability. For all compounds, linearity in matrix was observed in the range LOQ–10 g L−1,and coefficients of determination R2ranged from 0.9982 to 0.9999. The analytical recoveries, relative tothe isotopic internal standard, measured at 10 and 50 ng L−1were in the range of 91–105%, with relativestandard deviations below 6% and method detection limit, based on the blank value +3 times the standarddeviation of the blank, ranged from 0.5 to 3 ng L−1. The final method developed was used to determinethe concentration of PFCs in 15 retail milk samples. None of these compounds were detected in cow milkanalyzed samples.