Determination Of Organophosphate Esters Research Articles

Determination of Organophosphate Esters in Water Samples Using Gas Chromatography– Mass Spectrometry (GC–MS) and Magnetic Solid-Phase Extraction (SPE) Based on Multi-Walled Carbon Nanotubes (MWCNTs)

A method based on gas chromatography–mass spectrometry (GC–MS), coupled with magnetic solid-phase extraction (SPE) with multi-walled carbon-nanotube (MWCNT)-coated iron oxide (Fe3O4) as the adsorbent, was developed for analyzing four organophosphate esters in ambient water samples. The magnetic, MWCNT composites were prepared by hydrothermal synthesis and characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, and superconducting quantum interference device magnetometry (SQUID). The extraction and desorption conditions, such as adsorbent dosage, adsorption time, eluent type, and eluent volume, were studied. The adsorbent was used to extract analytes within 50 min. The limit of detection (LOD) was between 0.038–1 μg/L, and the limit of quantitation (LOQ) was between 0.10–3.59 μg/L. The method was applied to analyze organophosphate esters in environmental water samples. A 72.5–89.1% recovery was obtained by analyzing spiked samples with low-, medium-, and high-concentration analytes. The relative standard deviations (RSDs) were less than 10%. This method displayed better sensitivity and accuracy; therefore, it could be successfully used to detect organophosphate esters in environmental water samples.

Analysis of Organophosphate Esters in Sediment Samples Using Gas Chromatography-Tandem Mass Spectrometry

Abstract An efficient extraction and purification method coupled to gas chromatography-tandem mass spectrometry (GC-MS/MS) with electron impact (EI) was developed to determine eight organophosphate esters (OPEs) in sediment samples. OPEs were extracted from the sediments through vortex oscillation for 1 min and ultrasonic extraction using 20 mL of n-hexane and acetone mixture (1:1, V/V) for 10 min, followed by purification by Florisil solid phase extraction (SPE) column and quantitative determination by GC-MS/MS. The result showed that this pretreatment method was simple and less solvent consumption. At three spiked levels of 10, 20 and 50 μg L−1, the recovery of OPEs (except TEP) was between 80% and 120%, and the limits of detection for OPEs were 0.31 to 64.51 ng L−1, showing a good precision and accuracy in the determination of OPEs in sediment.

Determination of Organophosphate Esters in Human Serum Using Gel Permeation Chromatograph and Solid Phase Extraction Coupled with Gas Chromatography-Mass Spectrometry

A gel permeation chromatograph (GPC) coupled with solid phase extraction and gas chromatography-mass spectrometric (GPC-SPE-GC/MS) method was developed to analyze seven kinds of organophosphate esters, including Tri-n-butylphosphate, Tri(2-chloroethyl)phosphate, Triphenyl phosphate, Tris(2-butoxyethyl) phosphate, Tri-o-tolylphosphate, Tri-m-tolylphosphate and Tri-p-tolylphosphate in human serum. The recoveries of cleanup methods between GPC-silica/alumina column and H2SO4-silica/sulfuric acid gel column were compared. The purification method with the GPC-silica/alumina column didn't destroy the structure of organophosphate esters (OPEs) and could effectively remove some proteins and lipid matrix influence in serum. The developed method was verified using the spiked blank and the spiked serum, and the good recoveries and reproducibilities were achieved. The recoveries of all of OPEs in spiked blank (n = 3) were all more than 75%. The recoveries of d12-TCEP and d15-TPhP in human serum samples (n = 9) were 86.3% ± 21.6% and 103.1% ± 16.5%, respectively. In human serum samples (n = 9), the detection ratios for TnBP, TCEP, TPhP, TBEP and m-TTP were more than 90% in all of the serum samples, p-TTP was only 30%, and o-TTP was not detectable. The concentrations of TnBP, TCEP, TPhP, TBEP and m-TTP in serum were 3.4–46.5 ng g−1 lipid, 248.6–958.2 ng g−1 lipid, < 4.2 ng g−1 lipid, < 49.9 ng g−1 lipid and < 23.1 ng g−1 lipid, respectively.

Determination of organophosphate esters in water samples using an ionic liquid-based sol–gel fiber for headspace solid-phase microextraction coupled to gas chromatography-flame photometric detector

A simple, low-cost and sensitive method for determining organophosphate esters (OPEs) in water samples has been developed based on headspace solid-phase microextraction (SPME) followed by gas chromatography-flame photometric detector. The ionic liquid (1-allyl-3-methylimidazolium tetrafluoroborate, [AMIM][BF4])-based coating was developed by sol–gel technology and employed for extracting analytes. The prepared coating performed stably at high temperatures (up to 335°C) and with a range of solvents. It can be used at least 200 times without an obvious decrease in extraction efficiency. The extraction capability of the new fiber was much higher than polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB) and polyacrylate (PA) fibers. The experimental parameters that influenced the extraction efficiency, including extraction time, extraction temperature, stirring rate and ionic strength were investigated and optimized. Under the optimal conditions, the method detection limits (S/N=3) were in the range of 0.7–12ngL−1, and the limits of quantification (S/N=10) were between 1.0 and 28ngL−1. The repeatability of a single fiber varied from 3.3 to 7.6% (intra-day precision, n=6) and 4.3 to 8.9% (inter-day precision, n=6). The reproducibility of fiber-to-fiber (n=6) was in the range of 3.1–9.4%. The proposed method was applied successfully for the determination of OPEs in lake water, wastewater, sewage treatment plant effluent, and tap water with recoveries varying from 75.2 to 101.8%. The results demonstrate that the proposed method is highly effective for analyzing OPEs in water samples.

Determination of organophosphate esters in air samples by dynamic sonication-assisted solvent extraction coupled on-line with large-volume injection gas chromatography utilizing a programmed-temperature vaporizer

An on-line method for the determination of airborne organophosphate esters based on dynamic sonication-assisted solvent extraction and large-volume injection (LVI) gas chromatography with nitrogen–phosphorous detection is introduced. The LVI is performed with a programmed-temperature vaporizer. The entire extracted fraction of 800 μl (hexane–methyl-tert.-butyl ether, 7:3, v/v) is introduced directly into the GC system without any clean-up step following extraction. The extraction and analysis step were completed in less than 15 min. The limit of detection of the investigated organophosphate esters was established to be in the range of 5–32 pg/filter. The correlation coefficients ( r 2) were investigated in the linear range study of the entire system and established to be ∼0.9900 for all the investigated organophosphates esters. Applications of the method was demonstrated with the extraction of air samples collected onto glass fiber filters from different indoor environments. Six organophosphate esters were found at the levels 0.4–138 ng/m 3.

Dynamic microwave-assisted extraction coupled on-line with solid-phase extraction and large-volume injection gas chromatography: determination of organophosphate esters in air samples.

An on-line method was developed for the extraction, cleanup, and analysis of airborne organophosphate esters collected on glass fiber filters. The extraction and cleanup step was performed by conducting the dynamic microwave-assisted extraction (DMAE) coupled to solid-phase extraction (SPE). This system was further connected to include large-volume injection gas chromatography. The Injection interface was a programmable temperature vaporizer. The system performance test was investigated using spiked glass fiber filters. The DMAE-SPE recovery of the organophosphate esters was found to be greater than 97%. The repeatability of the uncorrected peak areas and the retention times was determined to be 4.2-8.0 and 0.03% relative standard deviation, respectively, and limits of detection were in the range 61-186.2 pg/m3. The method was tested in a newly restored office, in which several of the targeted organophosphate esters were detected. The total sampling and analysis time was less than 1.5 h.