Micellar electrokinetic chromatography with acid labile surfactant

We present a study of a degradable surfactant, sodium 4-[(2-methyl-2-undecyl-1,3-dioxolan-4-yl)methoxy]-1-propane sulfonate that is also known as an acid-labile surfactant (ALS). The performance of ALS as a pseudostationary phase is assessed and compared with established pseudostationary phases such as sodium dodecyl sulphate (SDS), volatile surfactants and polymeric micelles. ALS achieves separation efficiency of 100,000–145,000 theoretical plates and relative standard deviation (RSD) of electrophoretic mobility (n = 5) of less than 3%. Retention factors with ALS are strongly correlated with those with SDS. This is shown by the R2 = 0.79 for all eleven analytes and an R2 = 0.992 for specifically the non-hydrogen bonding (NHB) analytes. However, ALS displays different selectivity than SDS for hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) solutes (R2 of 0.74 and 0.88, respectively). ALS is degraded to less surface active compounds in acidic solution. These less surface-active compounds are more compatible with the electrospray ionization mass spectrometry (ESI-MS). ALS has a half-life of 48 min at pH 4. ALS has the potential to couple micellar electrokinetic chromatography (MEKC) with the ESI-MS. ALS can be used as a pseudostationary phase for a high efficiency separation and later acid hydrolyzed to enable an ESI-MS analysis.

► Acid-labile surfactant (ALS) commercially known as RapiGest is used for the first time in MEKC.
► ALS displays comparable separation efficiency as SDS and outperforms other ESI-compatible surfactant such as PFOS.
► ALS displays different selectivity for more polar analytes compared to SDS.
► ALS can be degraded to less surface-active products that are compatible with the ESI-MS.
► ALS is attractive for MEKC-fraction collection mass spectrometry.