Fig. 1From: Universal electronic-cigarette test: physiochemical characterization of reference e-liquidA Standard Operating Procedure (SOP) for e-liquid Reference Material formulation by adopting ISO Guide 35:2006E (Reference Materials: General and Statistical Principles for Certification) guideline. The reference e-liquid was characterized by measuring quality, homogeneity, stability and traceability of each component of the e-liquidBack to article page