ICP-MS Determination of 23 Elements of Potential health Concern in Liquids of e-Cigarettes. Method Development, Validation, and application to 37 Real Samples.

Introduction:
This article presents a study on the determination of 23 elements of potential health concern in liquids for electronic cigarettes (e-liquids) using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The study aimed to develop and validate an ICP-MS method for the reliable sampling of e-liquids produced in Sardinia, Italy, with particular attention paid to the critical phases of sample pre-treatment and optimization of ICP-MS conditions for each element and quantification.

Key Points:

* The study used a 1:100 (w/v) dilution of e-liquids in a synthetic matrix (SM) and microwave-assisted mineralization for sample pre-treatment.
* The ICP-MS method was optimized for 23 elements, including al, as, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, hg, Li, Mn, Mo, Ni, Pb, Se, Sb, Sn, Tl, U, and Zn.
* External calibration using a synthetic matrix and internal calibration using multiple additions of standard solutions were used for quantification.
* The method was validated in terms of limit of detection (LoD), limit of quantification (Loq), and precision, with recoveries between 81% and 118% for a synthetic e-liquid.
* The study found that all e-liquids considered exhibited a very low amount of the evaluated analytes, with only six elements out of 36 (i.e., as, Co, Cr, Fe, Li, and Mn) exhibiting a mean concentration higher than the Loq.
* The amounts of toxic elements found in e-liquids were coherent with a negligible health risk associated with their intake by vapers.
* The data measured also gave an account for the slight differences among the three classes of flavors, with tobacco flavors exhibiting the highest amounts of the considered elements and tonic flavors being the least abundant.

Main Message:
The study demonstrates the development and validation of an ICP-MS method for the determination of 23 elements of potential health concern in e-liquids. The method was applied to 37 different e-liquids, and the data obtained showed that the amounts of toxic elements found in e-liquids were negligible, with no significant health risk associated with their intake by vapers. The study also highlighted the importance of proper sample pre-treatment and quantification methods in ensuring accurate and reliable results in the determination of trace elements in complex matrices such as e-liquids. Overall, the study provides valuable insights and tools for regulators and researchers in the field of e-cigarette safety and regulation.

Mara a, Langasco I, Deidda S, et al. ICP-MS Determination of 23 Elements of Potential health Concern in Liquids of e-Cigarettes. Method Development, Validation, and application to 37 Real Samples. Molecules (Basel, Switzerland). 2021;26(21). doi:10.3390/molecules26216680