title: Assessment of nicotine concentration in electronic nicotine delivery system (ENDS) liquids and precision of dosing to aerosol.
abstract: BACKGROUND
  Global use of electronic nicotine delivery systems (ENDS; also called electronic cigarettes, e-cigarettes) has increased dramatically in recent years. However, due to the limited safety studies and growing concerns on the potential toxicity from long term use of ENDS, many national and international governments have employed regulatory measures to curtail its use. One of the most significant challenges regulators of ENDS encounter is the lack of quality standards to assess ENDS, e-liquid (solution used with ENDS which contain nicotine--a highly toxic and addictive substance), and amount of nicotine delivery to aerosol during ENDS use.
  
  
  OBJECTIVE
  Aims of the study were to (1) measure and compare nicotine concentration in e-liquids to values reported by manufacturers on packaging labels; (2) assess the precision of nicotine delivery from tank during aerosol formation. Methods: Nine popular Polish e-liquids (based on the market share data from October 2014) were purchased for the study. The labelled nicotine concentration for the selected e-liquids ranged between 11-25 mg/mL. All e-liquids were aerosolized in the laboratory using a smoking simulation machine (Palaczbot). Each e-liquid was aerosolized in a series of 6 consecutive bouts. A single bout consisted of 15 puffs with the following puff topography: 65 mL puff volume, 2.8 sec. puff duration, and 19 sec. interpuff interval. A total of 90 puffs were generated from each e-liquid. Nicotine content in the e-liquids and the aerosol generated were determined by gas chromatography with thermionic sensitive detection (GC-TSD).
  
  
  RESULTS
  For seven of nine analyzed e-liquids, the difference between measured and manufacturer labeled nicotine concentration was less than 10%. Nicotine dose in aerosol per bout ranged between 0.77-1.49 mg (equivalent to one-half the nicotine a smoker inhales from a single combustible cigarette).
  
  
  CONCLUSIONS
  Our analysis showed the high consistency between the labeled and measured nicotine concentration for popular on the Polish market ENDS e-liquids. Also, our analysis demonstrates that the risk for nicotine overdose is likely minimal when ENDS are used in a similar manner as a combustible cigarette. However, due to the toxicity risk nicotine poses regulatory measures focused on safety and quality of e-liquids should continually be exercised.
authors.forename: Leon
authors.initials: L
authors.lastname: Kosmider
authors.forename: Andrzej
authors.initials: A
authors.lastname: Sobczak
authors.forename: Izabela
authors.initials: I
authors.lastname: Szołtysek-Bołdys
authors.forename: Adam
authors.initials: A
authors.lastname: Prokopowicz
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Skórka
authors.forename: Oluyadi
authors.initials: O
authors.lastname: Abdulafeez
authors.forename: Bartosz
authors.initials: B
authors.lastname: Koszowski
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D002849:Chromatography, Gas; D066300:Electronic Nicotine Delivery Systems / Q000592:standards*; D006801:Humans; D009538:Nicotine / Q000032:analysis*
chemical_list: D000336:Aerosols; D009538:Nicotine