Liquid chromatography-electrospray ionization tandem mass spectrometry and liquid chromatography with fluorescence detection for determination of octylphenol and nonylphenol in municipal wastewater at trace levels

Removal and fate of endocrine disruptors chemicals under lab-scale postreatment stage. Removal assessment using light, oxygen and microalgae

The aim of this study was to assess the effect of light, oxygen and microalgae on micropollutants removal. The studied micropollutants were 4-(1,1,3,3-tetramethylbutyl)phenol (OP), technical-nonylphenol (t-NP), 4-n-nonylphenol (4-NP), Bisphenol-A (BPA). In order to study the effect of the three variables on the micropollutants removal, a factorial design was developed. The experiments were carried out in four batch reactors which treated the effluent of an anaerobic membrane bioreactor. The gas chromatography mass spectrometry was used for the measurement of the micropollutants. The results showed that light, oxygen and microalgae affected differently to the degradation ratios of each micropollutant. The results showed that under aerated conditions removal ratios higher than 91% were achieved, whereas for non-aerated conditions the removal ratios were between 50% and 80%, except for 4-NP which achieved removal ratios close to 100%. Besides, mass balance showed that the degradation processes were more important than the sorption processes.

Liquid Chromatography with Fluores-cence Detection as a Tool for Separation of Endocrine Disrupting Alkylphenols and their Mono- and Diethoxylates in Analysis of River Water Samples

A simple, accurate and reproducible reversed-phase high performance liquid chromatography method with fluorescence detection was developed for determination of octylphenol, nonylphenol and their short-chain ethoxylates, using an octadecyl silica column. The mobile phase used for the analysis consisted of methanol, acetonitrile and water (50:15:35). The analytes were separated successfully within a reasonable time without gradient elution, which was not achieved previously. Thus, use of inexpensive fluorescence detection instead of MS detection was enabled. This chromatographic method, combined with solid-phase extraction, was highly applicable for the simultaneous determination of octyl- and nonylphenol as well as their mono- and diethoxylates in real river water samples. The limit of detection (LOD) for octylphenol and its ethoxylates was 0.05 μg · L−1. For nonylphenol the LOD was 0.14 μg · L−1 and for its ethoxylates it was 0.15 μg · L−1. Recovery of octylphenol and its ethoxylates was about 80%. Recovery of nonylphenol and its ethoxylates was slightly lower (from 60 to 76%).

Development of a fast liquid chromatography-tandem mass spectrometry method for the determination of endocrine-disrupting compounds in waters

A fast liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) method was developed to study five endocrine-disrupting compounds (4-n-nonylphenol, bisphenol A, estrone, 17β-estradiol and 17α-ethinylestradiol) in water. Different columns were tested; the chromatographic separation of the analytes was optimized on a Pinnacle DB biphenylic column with a water-acetonitrile gradient elution, which allowed the separation of the selected endocrine-disrupting compounds (EDCs) in less than 6 min. Quantitative analysis was performed in selected reaction monitoring (SRM) mode; two transitions were chosen for each compound, using the most abundant for quantitation. Calibration curves using bisphenol A-d (16) as internal standard were drawn, showing good correlation coefficients (0.9993-0.9998). All figures of merit of the method were satisfactory; limits of detection were in the low pg range for all analytes. The method was then applied to the determination of the analytes in real water samples: to this aim, polar organic chemical integrative samplers (POCIS) were deployed in the influent and in the effluent of a drinking water treatment plant in Liguria (Italy). The EDC level was rather low in the influent and negligible in the outlet, reflecting the expected function of the treatment plant.

Gas chromatography–mass spectrometry analysis of alkylphenols in produced water from offshore oil installations as pentafluorobenzoate derivatives

A simple, highly selective and sensitive method for the determination of 14 representative alkylphenols from phenol (C0) to nonylphenol (C9) in produced water is described. Solid-phase extraction (SPE) by anion-exchange sorbent is used to extract alkylphenols from produced water. The samples are then derivatised by pentafluorobenzoyl chloride and analysed on GC-MS (negative ion chemical ionisation, NCI). The derivatisation procedure has been validated by means of two-level factorial design (2(7-4)) experiments. Quantification is done with isotope dilution of five internal standards of different alkyl chain length. The detection limits were at low ng/l levels. A comparison with GC-MS analysis of non-derivatised alkylphenol samples revealed the advantage of derivatisation as described in the method.