Method development and validation of dissolution testing for nicotine release from smokeless tobacco products using flow-through cell apparatus and UPLC-PDA.

Developing dissolution testing methods to measure the nicotine release profiles from smokeless tobacco products is valuable for product assessment and product-to-product comparisons. In this work, we developed a robust dissolution method to study the in vitro release of nicotine from smokeless tobacco products using the U.S. Pharmacopeia flow-through cell dissolution apparatus 4 (USP-4). We further developed and validated a sensitive Ultra Performance Liquid Chromatography coupled to Photodiode Array detector (UPLC-PDA) method for the accurate quantitation of the released nicotine into artificial saliva, which is our selected dissolution medium. We have successfully shown the applicability of the validated method by investigating the release profiles of nicotine from various commercial and CORESTA reference smokeless tobacco products [CRP 1.1 (Swedish-style snus pouch), CRP 2.1 (American-style loose moist snuff), CRP 4 (loose-leaf chewing tobacco) and CRP 4.1 (chopped loose-leaf chewing tobacco)]. Nicotine release profiles were analyzed by calculating the difference factor (f1) and similarity factor (f2) by adopting a methodology referenced in the Guidance for Industry from FDA's Center for Drug Evaluation and Research (CDER) and by fitting the release profile curves using a first order kinetic model. Nicotine release was found to be dependent on the form and cut of the smokeless tobacco products, with a slower release observed for snus and loose-leaf, compared to chopped and loose moist snuff smokeless tobacco. This dissolution methodology can be extended to measure and compare release of other constituents from smokeless tobacco products and has the potential for method standardization.

Method for the Determination of Carbonyl Compounds in E-Cigarette Aerosols.

Low levels of thermal degradation products such as carbonyls (formaldehyde, acetaldehyde, acrolein, crotonaldehyde) have been reported in e-cigarette aerosols. The collection and analysis of e-cigarette aerosol carbonyls are often adapted from methods developed for tobacco cigarette smoke. These methodologies are often not sensitive enough to detect low carbonyl levels in e-cigarette aerosols. One objective of this work was to develop and validate a rapid, selective and sensitive ultra-performance liquid chromatography with mass spectrometry method optimized for analysis of carbonyls in e-cigarette aerosols. Aerosols were trapped in 20-puff collections, 4-s durations, 55-mL volumes, 30-s intervals, square wave puff profiles. Collection apparatus involved a linear smoking machine with Cambridge filter pad followed by a glass impinger containing acidified 2,4-dinitrophenylhydrazine. This method showed limits of quantitation and detection of 0.016 and 0.003 µg puff-1, respectively, and run time of 4 min. Six e-cigarettes were evaluated (five devices each). All contained measurable levels of carbonyls. Levels were mostly well below those in conventional cigarettes. However, for some e-cigarettes, formaldehyde levels were above those for tobacco cigarettes (highest at 14.1 µg puff-1). Temperatures related to carbonyl yields in e-cigarette aerosols were explored to better understand carbonyl formation: formation of formaldehyde is low at temperatures below 350°C.

Characterization of potential impurities and degradation products in electronic cigarette formulations and aerosols.

E-cigarettes are gaining popularity in the U.S. as well as in other global markets. Currently, limited published analytical data characterizing e-cigarette formulations (e-liquids) and aerosols exist. While FDA has not published a harmful and potentially harmful constituent (HPHC) list for e-cigarettes, the HPHC list for currently regulated tobacco products may be useful to analytically characterize e-cigarette aerosols. For example, most e-cigarette formulations contain propylene glycol and glycerin, which may produce aldehydes when heated. In addition, nicotine-related chemicals have been previously reported as potential e-cigarette formulation impurities. This study determined e-liquid formulation impurities and potentially harmful chemicals in aerosols of select commercial MarkTen(®) e-cigarettes manufactured by NuMark LLC. The potential hazard of the identified formulation impurities and aerosol chemicals was also estimated. E-cigarettes were machine puffed (4-s duration, 55-mL volume, 30-s intervals) to battery exhaustion to maximize aerosol collection. Aerosols analyzed for carbonyls were collected in 20-puff increments to account for analyte instability. Tobacco specific nitrosamines were measured at levels observed in pharmaceutical grade nicotine. Nicotine-related impurities in the e-cigarette formulations were below the identification and qualification thresholds proposed in ICH Guideline Q3B(R2). Levels of potentially harmful chemicals detected in the aerosols were determined to be below published occupational exposure limits.