Occurrence and Fate of Feminizing Chemicals in Aquatic Environment – Method Development and Data Interpretation
Date Issued
2012
Date
2012
Author(s)
Chen, Wen-Ling
Abstract
This study developed and validated a method for measuring ten feminizing chemicals 4-tert-octylphenol, 4-nonylphenol (NP), nonylphenoxy acetic acid (NP1EC), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), estrone, 17β-estradiol, estriol, 17α-ethinyl estradiol and bisphenol A (BPA) in river water, sediment, and tissues using ultra-high performance liquid chromatography/tandem mass spectrometry (UHPLC/MS/MS) and isotope-dilution techniques. Analytes in water samples were extracted using disk-type automated solid-phase extraction (SPE). Solid samples of sediment, fish, and clams were treated with matrix solid-phase dispersion (MSPD) using C8 adsorbent; eluents of methanol and acetone were directly passed through following alumina cartridges for cleanup. The signal intensities of analytes on electrospray ionization (ESI) were compared with that of atmospheric pressure photoionization (APPI). The analytes were separated on a UHPLC C18 column with aqueous 10-mM ammonium acetate for NPEOs and aqueous 10-mM N-methylmorpholine for the other compounds. The organic mobile phase was methanol. Two-dimensional liquid chromatography (2-D LC) with a C4 restricted access material column was evaluated for on-line cleanup.
ESI provided satisfactory response for all of the analytes. Although APPI provided better signal intensities for the steroid estrogens (1.0-2.4 times higher) and the phenols (3.2-4.4 times higher) than ESI, it did not offer good responses on NP1EO, NP2EO and NP1EC. UHPLC shortened chromatographic time to less than 10 min (including re-equilibration). Disk-type automated SPE and MSPD dramatically increased the throughput of sample preparation. The extraction efficiency of most analytes on surface water ranged from 60% to 91%, but that of alkylphenolic compounds were lower than 30%. The extraction efficiency of MSPD on sediment, fish, and clams was 51-101%, 36-109%, and 30-111%, respectively. Acidic alumina cleanup was essential for the analysis of the tissue samples, and reduced matrix effects more significantly than 2-D LC on-line cleanup. The limits of detection (LODs) in water ranged from 0.81 ng/L to 89.9 ng/L. The LODs in sediment and tissues ranged from tens of pg/g wet weight (w.w.) to only a few ng/g w.w. This method proved to be accurate and reproducible, as both quantitative biases and relative deviations remained smaller than 20% at three spiked levels.
The method was applied to investigate the distribution of feminizing chemicals in river water, sediment and fish (Oreochromis niloticus) in the Dan-Shui River, Taipei, Taiwan. Sampling was conducted every one and a half months for nine months, in the total of six times. Sixty six water samples, 66 sediment ones and 114 fish were collected. The concentrations in fish tissues were measured to estimate the distribution and the bioaccumulation of these chemicals within fish.
Alkylphenolic compounds and BPA were detected in all of the water samples. BPA and NP were the most abundant analytes in river water (508 ± 634 ng/L and 491 ± 570 ng/L, respectively, n = 66). The average concentrations of BPA in the main stream of the Dan-Shui River (921 ± 635 ng/L, n = 18) was more than twice higher than that in the tributary (353 ± 567 ng/L, n = 48). The spatial variation of concentrations in water may be associated with the downstream pollution and the emission of untreated municipal wastewater. NP was the most abundant compound in sediment (770 ± 602 ng/g w.w., n = 66) and the highest concentration was detected at the closest downstream site from a wastewater treatment plant (1,701 ± 1,374 ng/g w.w., n = 6), indicating long-term accumulation of NP in sediment.
NP was also the predominant compound in fish tissues (199 ± 133 ng/g w.w. in muscle, n = 114) and had the highest bioaccumulation factor (BAF, 967 ± 903 in muscle, n = 114) among the analytes. Although BPA is easy to degrade in water and is eliminated rapidly in some fish species, up to 334 ng/g w.w. was detected in fish muscle and considerable BAFs (246 ± 801 in muscle, n = 114) were found. Concentrations of feminizing chemicals in fish organs were found to be higher than that in muscle and the BAFs of NP, nonylphenol ethoxylates and BPA showed similar trends in organs: gonad > liver > muscle. The high BAFs of NP in liver and in gonad (9,576 ± 15,048 and 27,287 ± 49,587, respectively, n = 114) indicated possible bioaccumulation. Low hepatosomatic indices (0.16 ± 0.10, n = 114) were significantly correlated with the concentrations of feminizing chemicals in river water, in fish muscle and in liver, indicating that feminizing compounds entered tilapia via river water and ingestion, concentrated and accumulated in the target organ, and affected the endocrine system. The accumulation of these compounds in the organs may attribute to the skewed sex ratio of fish (female:male = 1.92). Future studies are desired to investigate the impacts of the interaction between these analytes and other emerging contaminants on biologial environments.
Subjects
endocrine disrupting chemicals
disk-type automated solid-phase extraction
matrix solid-phase dispersion
bioaccumulation factor
fish organs
SDGs
Type
thesis
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