Method development for the analysis of mono-carbonyl compounds in e-vapor products by LC-MS
At the 73rd Tobacco Science Research Conference (TSRC), we presented a novel method for quantitation by LC-MS of mono-carbonyl compounds in e-vapor product aerosol samples. The method is simple and robust with good recoveries. We have since extended the method validation to include e-liquid samples (recoveries 90.2 - 111.8 %) for the same mono-carbonyls (formaldehyde, acetaldehyde, acrolein and crotonaldehyde). In this presentation, we will discuss the extension to e-liquids. We will also present the steps we have taken during the method development process to optimize the method and to overcome challenges specifically related to the analytes and/or the matrix in question. Analysis of carbonyl compounds is challenging due to environmental contamination and relative instability of the analytes. E-vapor product aerosol and e-liquid matrices are problematic for instrument maintenance issues. Details will be provided for method development and optimization related to managing samples with no to low levels of analyte with a high environmental background and steps taken to optimize the conditions for the conversion of free carbonyls to 2,4-dinitrophhenylhydrazine (DNPH) derivatives for detection and analyte stability purpose; for improving sensitivity and selectivity and chromatographic baseline noise to optimize the method LOQs; and for ways to make the method robust enough for maintenance and linear dynamic range for use in a production lab. The method has a calibration range of 2 to 400 ng/mL for all four analytes, with limit of quantitation (LOQ) at 2 ng/mL, or 0.0029 µg/puff for aerosol, or 0.4 µg/g for e-liquids.