Two Techniques for the Analysis of WS-3 With Potential Application to the Analysis of Other Cooling Agents *

Abstract

WS-3 (N-ethyl-p-menthane-3-carboxamide) is a compound used as a cooling agent for tobacco or nicotine products. Three other similar compounds WS-23 (N,2,3-trimethyl-2-propan-2-ylbutanamide), Evercool 180 (N-p-benzene-acetonitrile menthanecarboxamide), and Evercool 190 (N-(2-pyridine-2-yl)ethyl-3-p-menthancarboxamide) also have cooling properties and can be used as tobacco additives. A few previously reported methods for WS-3 analysis were rather complex, and the goal of present work was to develop a simple, rapid, and accurate procedure for simultaneous analysis of WS-3 and of the other three cooling compounds. For this purpose, a LC/MS procedure has been developed that requires 6-min runs. The method was calibrated to analyze solutions containing each analyte in the range of concentrations between 48.8 ng/mL to 12.5 µg/mL. The procedure is selective and shows excellent precision with typical RSD lower than 3%. In parallel to the LC/MS method, a GC/MS procedure was also developed mainly with the goal of having a proof of the accuracy for both methods. This GC separation requires 20-min runs. The GC/MS technique was calibrated to analyze solutions containing each analyte in the range of concentrations between 1.56 µg/mL to 125 µg/mL for WS-23 and WS-3, from 6.25 µg/mL to 125 µg/mL for Evercool 180, and from 3.13 µg/mL to 125 µg/mL for Evercool 190. The sensitivity of the LC/MS method is significantly higher than the GC/MS one, and for the analysis of traces of cooling agents the LC/MS method is recommended. The LC/MS method was applied for the analysis of WS-3 in tobacco, cigarette smoke, flavor solutions, and in nicotine pouches. No samples containing the other cooling agents were available. [Contrib. Tob. Nicotine Res. 32 (2023) 26–33]

Keywords

• ws-3
• ws-23
• evercool 180
• evercool 190