title: Nicotine concentrations in electronic cigarette refill and do-it-yourself fluids.
abstract: BACKGROUND
  We evaluated the accuracy of nicotine concentration labeling on electronic cigarette refill products.
  
  
  METHODS
  The nicotine concentration of 71 electronic cigarette refill fluid products and 1 related do-it-yourself (DIY) product was quantified using high-performance liquid chromatography. Quantified data were compared with manufacturers labeled concentrations. Duplicate refill fluid products purchased at different times were evaluated by visual comparison of fluid coloration and quantified nicotine concentration.
  
  
  RESULTS
  Thirty-five of the 54 nicotine-containing fluids had quantified nicotine concentrations that deviated by more than ± 10% from the manufacturer labels, with 46 of 50 being in excess of labeled values. Refill fluids labeled as 0 nicotine had no detectable nicotine. Of the 5 products that were unlabeled for nicotine concentration, 3 contained no detectable nicotine, whereas the remaining 2 contained nicotine in excess of 100mg/ml and may have been intended for DIY use. Sixteen of the 18 duplicate bottles of refill fluid varied greatly in their nicotine concentrations. One of the 5 companies showed significant improvement in labeling accuracy among the most recently purchased products. Of the 23 total duplicate pairs, 15 of 23 varied in coloration from their mates.
  
  
  CONCLUSIONS
  Nicotine concentration labeling on electronic cigarette refill products was often inaccurate but showed improvement recently in products from 1 company. To ensure the safety of refill fluids and DIY products, it is necessary to establish quality control guidelines for the manufacturing and labeling and to monitor products longitudinally.
authors.affiliation: Cell Molecular and Developmental Biology Graduate Program, University of California, Riverside, CA; Department of Cell Biology and Neuroscience, University of California, Riverside, CA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Davis
authors.affiliation: Department of Cell Biology and Neuroscience, University of California, Riverside, CA.
authors.forename: Michael
authors.initials: M
authors.lastname: Dang
authors.affiliation: Department of Cell Biology and Neuroscience, University of California, Riverside, CA.
authors.forename: Jisoo
authors.initials: J
authors.lastname: Kim
authors.affiliation: Cell Molecular and Developmental Biology Graduate Program, University of California, Riverside, CA; Department of Cell Biology and Neuroscience, University of California, Riverside, CA talbot@ucr.edu.
authors.forename: Prue
authors.initials: P
authors.lastname: Talbot
mesh_terms: D002851:Chromatography, High Pressure Liquid; D066300:Electronic Nicotine Delivery Systems; D006801:Humans; D009538:Nicotine / Q000032:analysis*; D011356:Product Labeling / Q000592:standards; D011786:Quality Control; D012907:Smoking; D014481:United States
chemical_list: D009538:Nicotine