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Abnormal behaviors in the calibration curves of liquid chromatography–tandem mass spectrometry occurring in the quantitative analysis of surfactants near critical micelle concentrations
Author(s) -
Lee Sang Tak,
Kim Hyeri,
Kwon JungHwan,
Oh Han Bin
Publication year - 2021
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.4599
Subject(s) - chemistry , critical micelle concentration , micelle , thermodynamics of micellization , calibration curve , sodium dodecyl sulfate , chromatography , mass spectrometry , pulmonary surfactant , electrospray ionization , ammonium bromide , electrospray , bromide , cationic polymerization , tandem mass spectrometry , liquid chromatography–mass spectrometry , organic chemistry , detection limit , aqueous solution , biochemistry
Surfactants, including quaternary ammonium compounds, are widely used in daily life as part of consumer chemical products and, more recently, in the shale oil industry. Because of their unique amphiphilic properties, surfactants form micelles at concentrations above a certain threshold known as the critical micelle concentration (CMC). A previous electrospray ionization mass spectrometry studies conducted by Siuzdak et al. and others presented indirect evidence regarding micelle formation. Herein, we have used liquid chromatography–tandem mass spectrometry to explore how such micelle formations affect the quantitative analysis of surfactants. Results reveal abnormal behaviors in the calibration plots of a few selected anionic and cationic surfactants, such as sodium decyl sulfate (SDeS), sodium dodecyl sulfate (SDS), myristyltrimethylammonium bromide (MTAB), and benzyldimethyloctadecylammonium chloride (BAC‐18). At concentrations close to the respective CMCs of these surfactants, the calibration plot for MTAB flattened, whereas the slopes of the calibration plots for SDeS, SDS, and BAC‐18 suddenly changed. These abnormal behaviors can be related to micelle formation. From a practical perspective, the above observations suggest that in the quantitative analysis of surfactants, high micelle concentrations close to the CMC should be avoided to obtain accurate surfactant measurements.