title: [The determination of phthalic acid esters in edible vegetable oils by gas chromatography-mass spectrometry].
abstract: OBJECTIVE
  We aimed to establish a quantified method for the 17 phthalate acid esters (PAE) in edible vegetable oil by gas chromatography-mass spectrometry (GC-MS) with the pretreatment of acetonitrile extraction and silica/N-(n-propyl)ethylenediamine (silica/PSA) mixed solid phase extraction column and evaluated the PAE of 25 edible oil samples from supermarkets in Hangzhou city.
  
  
  METHODS
  The internal standard solution (D4-DEHP) was added in edible vegetable oil sample. The analytes were extracted by acetonitrile with 1 min vortex, and centrifuged at 3050×g for 5 min. The supernatant was then cleaned with silica/PSA column, and eluted with acetonitrile. The elution was dried with N2 flow at 50°C and diluted to 1.0 ml with hexane. Then, 17 PAE were tested by GC-MS and quantified with internal standards. The repeatability and sensitivity of the assay were evaluated. PAE were then determined in 25 plastic buckets of edible vegetable oil from supermarkets in Hangzhou city.
  
  
  RESULTS
  By the quantification of internal standard of D4-DEHP, a good linearity range of related 17 PAE was observed. The correlation coefficient was 0.994-1.000 and the standard lowest quantified level was 0.05-0.15 µg/ml. The spiking recoveries of 17 PAE were 78.3%-108.9% with the RSD of 4.3%-12.1% (n=6). The method detection limits were 0.1-0.2 mg/kg. In 25 plastic buckets of edible vegetable oil from Hangzhou, DMP, DEP, DIBP, DBP and DEHP were detected at the range of <0.1-1.8 mg/kg and the detection rates were 12% (3/25), 24% (6/25), 100% (25/25), 96% (24/25) and 100% (25/25), respectively. Other 12 PAE was not detected. For DBP with the level of <0.1 to 1.3 mg/kg, the results of 16% (4/25) samples exceeded the regular migrating limit of 0.3 mg/kg. For DEHP of <0.2-1.8 mg/kg, the data of 12% (3/25) samples were beyond the regular migrating limit of 1.5 mg/kg.
  
  
  CONCLUSIONS
  The pretreatment by silica/PSA mixed solid phase extraction column can satisfy the PAE determination requirements in edible vegetable oils. The DMP, DIBP, DEP, DBP and DEHP were detected from the survey of 25 edible oil samples in Hangzhou city.
authors.affiliation: Institute of Physical and Chemical Inspection, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051, China. pgwu@cdc.zj.com
authors.forename: Ping-gu
authors.initials: PG
authors.lastname: Wu
authors.forename: Da-jin
authors.initials: DJ
authors.lastname: Yang
authors.forename: Xiang-hong
authors.initials: XH
authors.lastname: Shen
authors.forename: Xiao-dong
authors.initials: XD
authors.lastname: Pan
authors.forename: Li-yuan
authors.initials: LY
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Tan
authors.forename: Liang
authors.initials: L
authors.lastname: Feng
authors.forename: Ying
authors.initials: Y
authors.lastname: Ying
mesh_terms: D004952:Esters / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D010795:Phthalic Acids / Q000032:analysis*; D010938:Plant Oils / Q000032:analysis*
chemical_list: D004952:Esters; D010795:Phthalic Acids; D010938:Plant Oils