Ammonium perfluorooctanoate as a volatile surfactant for the analysis ofN-methylcarbamates by MEKC-ESI-MS

Abstract

Ammonium perfluorooctanoate (APFOA) was investigated as an MS-friendly surfactant for the analysis of a mixture of ten N-methylcarbamates with MEKC-ESI-MS. Because of the relatively low boiling point of perfluorooctanoic acid ( approximately 190 degrees C), APFOA can be introduced into a mass spectrometer without the adverse effects of less volatile surfactants such as SDS. With a BGE consisting of 50 mM APFOA/isopropanol (IPA) 98:2 and with 30 kV applied, a very fast separation ( approximately 6 min) was possible with only one pair of analytes comigrating. Using an experimental design with four factors (voltage, nebulizer pressure, concentration of APFOA, and concentration of IPA) we were able to resolve all analytes in just over 11 min. Sheath liquid composition and flow rate, drying gas temperature and flow rate, and fragmentor voltage were then optimized for maximum signal intensity and S/N. It was found that the faster method gave better S/N because of narrower peak widths, and detection limits in SIM mode were between 0.01 (aldicarb) and 0.08 mg/L (methomyl). Calibration curves were prepared with standards of 0.50, 1.00, and 2.00 mg/L for the analysis of samples obtained after SPE of tap water spiked with the ten N-methylcarbamates at a level of 10 microg/L. All analytes showed very good recoveries (>86%), except for the most polar analyte aldicarb sulfone (recovery of 73%), testifying for the potential use of APFOA for this kind of analyses.

Recent advances in CE and CEC of pollutants

“…Various approaches, including the improvement of detection system capabilities and/or preconcentration techniques, as outlined in Sections 2 and 3, have been proposed. This has resulted in the development of CE as an advantageous analytical tool that provides the separation power and detectability necessary for the analysis of trace amounts of pesticides [27,33,41] and herbicides [31,32,50,51,64,[89][90][91] in different environmental matrices.…”

“…Many novel chromatographic and electrophoretic preconcentration techniques, as well as combinations of these procedures, have been recently applied [26,34,49,[64][65][66][67][68][69][70][71][72]. Off-line sample cleanup and preconcentration have been employed through the use of SPE [26,32,34,49,50,64,70], stir bar sorption extraction (SBSE) [67], polymer-coated hollow fiber microextraction [65], and liquid-liquid semi-microextraction (LLsME) [71].…”

“…New CE/MEKC-MS methods for the trace analysis of pesticides and herbicides have recently appeared in the literature [50,51]. For example, the MEKC-ESI-MS method using ammonium perfluoroctanoate (APFOA), an MS-friendly surfactant, was developed for the analysis of ten N-methylcarbamates [50].…”

“…For example, the MEKC-ESI-MS method using ammonium perfluoroctanoate (APFOA), an MS-friendly surfactant, was developed for the analysis of ten N-methylcarbamates [50]. With a BGE consisting of 85 mM APFOA (pH 9)/isopropanol (97:3), and an applied voltage of 23.5 kV, the ten N-methylcarbamates were separated within 11 min.…”

“…The coupling of MEKC with MS is still in its very early stages. In the past 2 years, new CE/MEKC/CEC-ESI-MS methods have been developed for determining pharmaceuticals [49], pesticides and triazines [50,51], organic acids [52], biodegradation products from sulfonated dyes [53], dialkylphthalates [47], PAHs [54], amines [55], nitrosamines [56], explosives [57,58], and surfactants [59,60].…”