Application of dispersive liquid–liquid extraction followed by rapid and direct mass spectrometry analysis to evaluate parabens in high salinity water sample

As an emerging marine pollutant, parabens have attracted more and more attention due to their widespread existence and potential toxicity in living organisms. In this work, a sensitive and accurate ultrasound-assisted liquid–liquid extraction (LLE) method, followed by a combination of nanoscale electrospray mass spectrometry detection technique, was proposed to determine the trace parabens in high salinity water sample. The method used only one organic solvent for the extraction and ionization of the target in simulated seawater samples. The extraction/ionization of salts is restrained due to their microsolubility or even insolubility in the extraction solvent (also spray solvent), which greatly enhanced the signal intensity of the target analytes and achieved desalination in the mass spectrometry. Several parameters that affect the extraction and ionization efficiencies were investigated. Under the optimal conditions (extraction solvent, 800 µL ethyl acetate; volume ratio of sample to organic phase, 6:1; extraction time, 7 min; nano-tube, a-nanotube; ionization voltage, 2.3 kV), the proposed method was effectively implemented for the detection of five parabens in different real water samples (seawater water and domestic water). The results showed that the limits of detection ranged between 0.21 and 1.11 ng mL⁻¹. In addition, satisfactory accuracy and precision were obtained in real seawater samples for all parabens. This study demonstrated that the combination of LLE and nanoscale electrospray technology is suitable for detecting analytes in high salinity such as seawater.