Analysis of the elements and metals in multiple generations of electronic cigarette atomizers

Abstract

Background: Since their release in 2004, electronic cigarettes (ECs) and their atomizers have undergone significant evolution.

Objective: The purpose of this study was to evaluate and compare the elemental/metal composition of atomizers in cartomizer and tank style ECs produced over a 5-year period.

Methods: Popular cartomizer and tank models of ECs were dissected and photographed using a stereoscopic microscope, and elemental analysis of EC atomizers was done using scanning electron microscopy coupled with energy dispersive x-ray spectroscopy.

Results: Eight elements/metals were found in most products across and within brands purchased at different times. These included chromium, nickel, copper, silver, tin, silicon, aluminum, and zinc. Iron and lead were found in some but not all products, while manganese, cobalt, molybdenum, titanium, and tungsten were only found in a few of the products. The metals used in various components were often similar in cartomizer and tank models. Filaments were usually chromium and nickel (nichrome), although in some newer products, the filament also contained iron, copper, and manganese. The thick wire in earlier products was usually copper coated with silver, while in some newer products, the thick wire was predominantly nickel. In all products, the wick was silica, and sheaths, when present, were fiberglass (silicon, oxygen, calcium, aluminum, magnesium). Wire-to-wire joints were either brazed or clamped with brass (copper and zinc), and air-tube-to-thick wire joints, when present, were usually soldered with tin. Tank style products generally lacked a thick wire and sheaths.

Conclusion: In general, atomizer components in ECs were remarkably similar over time and between brands. Certain elements/metals were consistently found in most models from all generations, and these should be studied carefully to determine if their transfer to aerosols affects user's health and if their accumulation in trash affects the environment.

Keywords: Atomizers; E-cigarettes; Electronic cigarettes; Metals; Tobacco products.

Figure 1:. Examples of atomizing units from a cartomizer (A) and tank (B) style EC.

(A) An atomizer from a cartomizer EC purchased in 2011. (B) The atomizer from a RDA tank style EC purchased in 2014. Individual components are labeled in each figure.

Figure 2:. Heat map showing the elements/metals in each component in each product.

Dark red squares indicate the element was a major peak in the EDS spectrum. Pink squares indicate elements were minor peaks in spectra. Dark gray squares indicate the component was not present. Light blue squares indicate components that were made of plastic and not analyzed.

Figure 3:. SEM images and EDS elemental maps of the filament, thick wire and wire-to-wire joint in EC.

(A) The filament in the BluCig atomizer was chromium (B) and nickel (C). (D) The filament in the BluCig Plus atomizer was of chromium (E), nickel (F), copper (G), and iron (H). (I) The filament in the V2 Cigs 2012 atomizer was chromium (J), nickel (K), and iron (L). (M) The filament in the Tsunami 2.4 atomizer was chromium (N), nickel (O), and iron (P). (Q) The filament in the Clone atomizer was chromium (R), iron (S), and aluminum (T). (U) The thick wire in the Mark Ten atomizer was copper (V) and silver (W). (X) The thick wire in a V2 Cigs 2017 atomizer was nickel (Y). (Z) The thick wire in the Mark Ten XL atomizer was chromium (AA), nickel (BB), and iron (CC). (DD) The filament-to-thick wire joint in the BluCig atomizer was copper (EE). (FF) The filament-to-thick wire joint in the BluCig Plus atomizer was copper (GG) and zinc (HH). (II) The filament-to-thick wire joint in the Kanger T3S atomizer was chromium (JJ) and nickel (KK). Orange arrow = thick wire, blue arrow = filament to thick wire joint.

Figure 4:. SEM images and EDS elemental map of the air-tube and wire-to-air-tube joint.

(A) The air-tube in the BluCig atomizer was copper (B), zinc (C), nickel (D), and gold (E). (F) The air-tube in the BluCig Plus atomizer was copper (G), zinc (H), nickel (I), and silver (J). The air-tube in the Mark Ten atomizer was silver (K) and nickel (L). (M) The air-tube/shell in Kanger T3S atomizer was copper (N), zinc (O), iron (P), nickel (Q), and tin (R). (S) The thick wire-to air-tube joint in the Mark Ten XL atomizer was iron (T), nickel (U), and chromium (V). (W) The thick wire-to-air-tube joint in the Mark Ten atomizer was tin (X). (Y) The thick wire-to-air-tube joint in the V2 Cigs 2017 atomizer was copper (Z), zinc (AA), and lead (BB). Orange arrow = core of the air-tube, green arrow = outer coating of the air-tube, red arrow = thick wire to air-tube joint.

Figure 5:. SEM images and EDS elemental map of the wick and sheath.

(A) The wick in the Vuse Vibe atomizer was silicon (B) and oxygen (not shown). (C)The wick in the Tsunami 2.4 atomizer was oxygen (D) and carbon (E). (F) The sheath in the Mark Ten XL atomizer was silicon (G), oxygen (not shown), magnesium (H), calcium (I), and aluminum (J). For Tsunami 2.4 wick, the oxygen and silicon are the same color.