Influence of charged aerosol detector instrument settings on the ultra-high-performance liquid chromatography analysis of fatty acids in polysorbate 80

Charged aerosol detector response modeling for fatty acids based on experimental settings and molecular features: a machine learning approach

“…The organic solvent content in the mobile phase was varied in a rather small range from 75 to 90% (v/v) in our experiments due to solubility issues of some fatty acids at higher aqueous proportions. In addition, the separation of fatty acids is often achieved using mobile phases with high organic contents on C18 stationary phases [21,39]. The CAD response did not notably change with organic solvent content, which was somewhat expected.…”

“…Thus, the selection of semi-volatile and non-volatile fatty acids that are structural homologues but differ significantly in their response was essential to develop a model that could accurately predict the CAD response based on a mixed model including the response-determining molecular descriptors. Previous studies on the CAD response of fatty acids revealed a pronounced decline in the response of myristic acid (C14) compared to its structural homologue palmitic acid (C16) [21]. With respect to this preliminary observation, fatty acids ranging from lauric acid (C12) to stearic acid (C18) were selected as test substances due to their estimated differences in CAD response.…”

“…The optimal evaporation temperature for a certain analyte requires experimental optimization, as the background noise of the CAD also changes with evaporation temperature due to enhanced evaporation of mobile phase impurities. However, at higher evaporation temperatures, analytes with semivolatile characteristics, such as the short/medium chain fatty acids lauric acid and myristic acid, are expected to suffer a substantial loss of response [21]. Therefore, lower evaporation temperatures are contributing to enhanced CAD response for these fatty acids, and, consequently, could result in improved S/N (Fig.…”

Development and validation of a rapid method to quantify neutral lipids by NP-HPLC-charged aerosol detector

“…This was anticipated given that for semi-volatile compounds such as oleic acid and monoolein, with a boiling point of 286 and 240 °C, respectively (U.S. Environmental Protection Agency, 2021), volatility determines particle formation. Therefore, a higher evaporation temperature leads to a decreased signal intensity (Schilling et al, 2018). For non-volatile compounds such as triolein and diolein having a boiling point above 500 °C, the signal intensity depends on the particle size distribution of the dried aerosol.…”

“…In general, all aerosol detectors generate calibration curves with non-linear behaviors. Thus, it is necessary to check the curve fit and pay special attention to low analyte concentrations (Schilling et al, 2018). This means that the traditional evaluation of the determination coefficient (R 2 ≈ 1) does not necessarily imply a good linear fit as this regression technique gives more weight to the high concentrations within the calibration curve.…”