An Online Solid Phase Extraction-Liquid Chromatography Tandem Mass Spectrometry Method for the Analysis of Parabens in Urban Waters

Abstract

In this work, we report a method to quantify methylparaben, ethylparaben, propylparaben and butylparaben in urban waters of São Carlos (São Paulo State, Brazil) by online solid phase extraction-liquid chromatography tandem mass spectrometry (SPE-LC-MS/MS) system. The method achieved ng L-1 limits with good accuracy and precision (internal standards for each paraben were used). The total run cycle time takes 9.5 min per sample including the extraction, cleanup and columns conditioning cycles, lower collection volumes of urban water and solvent usage. The SPE cartridge applied showed robustness allowing over 500 sample injections (800 μL each) with good chromatographic performance. This study findings included the detection of parabens in samples in São Carlos.

Selective Antibacterial Activity of Palmitoleic Acid in Emulsions and Other Formulations

“…This is because the transfer of FA molecules from the aqueous phase to the cell membrane is essential for antibacterial activity (Moran et al, 2017). The hydrophobic value (about 6) of 16:1 FA was higher than general preservatives such as paraben (logP = 1.6–3.2) (Miura and Nonomura, 2019; Nascimento and Cass, 2021). Therefore, we predicted that some FA molecules distributed to the aqueous phase contributed to antibacterial activity.…”

Determination of parabens in wastewater samples via robot‐assisted dynamic single‐drop microextraction and liquid chromatography–tandem mass spectrometry

“…Parameters independent of the Cartesian robot operation, such as extraction solvent, stirring, and salting-out effect, were investigated through univariate experiments. A 2 4 factorial experimental design was employed to determine the effect of drop volume (v1), drop exposure time (v2), drop draw/eject cycles (v3), and time between drops (v4). The complete 2 4 factorial experimental design is presented in Table S1.…”

“…A 2 4 factorial experimental design was employed to determine the effect of drop volume (v1), drop exposure time (v2), drop draw/eject cycles (v3), and time between drops (v4). The complete 2 4 factorial experimental design is presented in Table S1. Finally, the extraction performance was studied by fine-tuning the drop exposure time and the number of drop draw/eject cycles through a central composite design (CCD), maintaining the drop volume and the time between drops at the lower tested levels (20 µl and 0 s, respectively).…”

“…Those variables influencing the extraction efficiency on SDME-such as the volume of the drops used, their exposure time, the number of extraction cycles performed, and the time of equilibrium between drops-can be easily controlled via the programming of the Cartesian robot. Therefore, these variables were studied through multivariate optimization in two stages: (i) the study of the effect of each variable on the chromatographic response via a factorial 2 4 experimental design and (ii) the determination of the optimal operating conditions via fine adjustment Initially, a 2 4 factorial design was performed (Table S1), and based on the chromatographic areas, the effects of each of the variables on the extraction efficiency were determined. Effects were calculated from the difference between responses at high and low levels for each variable and their interaction.…”

“…Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the paramount technique for analyzing organic pollutants from water samples [3,4]. LC-MS/MS provides spread applicability scope and outstanding sensitivity and selectivity.…”