title: [The application of UPLC-MS/MS to detect precursors of perfluorooctanoic acid and perfluoroalkyl carboxylatesin serum].
abstract: OBJECTIVE
  We established a method of UPLC-MS/MS that was to detect fifteen precursors of perfluoroalkyl sulfonates (PFSA) and perfluoroalkyl carboxylates (PFCA) in serum.
  
  
  METHODS
  Briefly, TBAS solution was added to sera, then the mixed solution was extracted with aliquots of MTBE. The MTBE aliquots were combined, evaporated to dryness under nitrogen, and reconsituted in 0.25 ml of methanol and water (1:1). Then the reconstituted solution through 0.2 µm nylon syringe filter was collected. Chromatographic separation was performed using a Waters ACQUITY (TM) BEH ¹⁸C column (50 mm × 2.1 mm × 1.7 mm). Analyte quantitation was performed in the negative electrospray ionization mode and multiple reaction monitoring (MRM).
  
  
  RESULTS
  Three target substances, 6: 6PFPi, 6: 8PFPi, 8: 8PFPi, were externally confirmed by standard addition. Rates of recovery for these three chemicals were from 41.01% to 112.13% in two standard levels. And the relative standard deviations (RSD) were lower than 11.63% and higher than 1.80%. The other twelve substances were quantified with internal standard. Moreover in two standard levels, rate of recovery for these chemicals ranged from 70.25% to 127.51%. And RSD were more than 1.23% and less than 15.45%. And the corresponding limit of detection (LOD) and limit of quantitation (LOQ) for all target substances were 0.1-5.0 pg/ml and 0.2-10.0 pg/ml. Then we detected these target substances in ten different human serum samples. The levels of few substances were higher than LOD. And the ranges of FOSA-M, N-EtFOSA-M, N-MeFOSAA, N-EtFOSAA were respectively < LOD-0.94 pg/ml, < LOD-10.08 pg/ml, < LOD-6.74 pg/ml, < LOD-1.04 pg/ml.
  
  
  CONCLUSIONS
  The method, with high sensitivity and accuracy, could meet the actual testing requirements.
authors.affiliation: National Institute for Nutrition and Food Safety, Chinese Center for Disease Prevention and Control, Beijing 100021, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shi
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Jingguang
authors.initials: J
authors.lastname: Li
authors.affiliation: Email: zhaoyf703@126.com.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Zhao
authors.forename: Yongning
authors.initials: Y
authors.lastname: Wu
mesh_terms: D002210:Caprylates; D005466:Fluorocarbons; D006801:Humans; D057230:Limit of Detection; D053719:Tandem Mass Spectrometry
chemical_list: D002210:Caprylates; D005466:Fluorocarbons; C023036:perfluorooctanoic acid