Tri-iso-butyl Phosphate Research Articles

Tri-iso-butyl phosphate (TiBP) exposure induces neurotoxicity by triggering oxidative stress accompanied by neurotransmitter system disruptions and apoptosis in zebrafish larvae

The current research sheds light on the biological toxicity of organophosphate flame retardants (OPFRs), yet it overlooks the neurotoxicity and potential molecular mechanisms of tris(1,3-dichloro-2-propyl) phosphate (TiBP), a prominent constituent of the OPFRs. To address this, we utilized zebrafish larvae as a model to investigate TiBP's acute toxicity and neurotoxic effects, along with the associated molecular pathways. Our findings revealed that the 96 h and 120 h LC50 values for TiBP were 56.51 mg/L and 48.85 mg/L, respectively. Gradient exposure based on the 120 h LC50 demonstrated that TiBP induced developmental toxicity, characterized by elevated heart rate, reduced body length, and diminished eye distance. Additionally, a decrease in swimming activity was observed in the light test, along with the inhibition of the neuro crest cell development in Tg (HuC:eGFP) and Tg (sox10: eGFP) zebrafish larvae following TiBP exposure, as well as the alterations of neurogenesis and ACh-related genes. Expression of key neurodevelopment genes, including mbpa, gap43, nestin, ngfra, was significantly downregulated. Furthermore, heightened anxiety-like behaviors in open field and phototaxis tests were observed, concomitant with neurotransmitter imbalances. Specifically, there was an increase in DA levels, a decrease in GABA, and an upregulation of AChE activity. These disruptions were primarily mediated through transcriptional dysregulation of neurotransmitter synthesis, transport, and reception. Upon exposure to TiBP, zebrafish larvae exhibited a concentration-dependent increase in both ROS level and apoptosis. An upregulation of antioxidant enzymes and their transcription levels indicated the presence of oxidative stress in the larvae. The induction of ddit3 was congruent with the observed apoptosis, suggesting that it may be triggered by oxidative stress via the ERs-CHOP pathway. In summary, our study indicates that oxidative stress is a pivotal molecular event in the neurotoxicity induced by TiBP, implicating the disruption of the GABAergic, dopaminergic, and cholinergic systems, as well as triggering apoptosis.

Organophosphate esters in reservoir water from a metropolitan city in the Guangdong-Hong Kong-Macao Greater Bay Area, China, and their ecological risk

Organophosphate esters (OPEs) are emerging flame retardants widely used in products such as furniture, electronic equipment, construction, and plastics. It has been demonstrated that OPEs are harmful to humans and aquatic organisms, thus posing a threat to ecosystems. Considering that reservoirs are critical sources of drinking water for residents in Southern China, this study quantified nine OPEs in water samples collected from 29 reservoirs and their tributaries. The temporal and spatial distributions of OPEs were analyzed and their ecological risks were assessed. The results showed an extensive presence of OPEs in reservoirs, and the median concentration of Σ9OPEs was much higher in the dry season (65.3 ng/L) than in the wet season (21.3 ng/L). Triisobutyl phosphate (TiBP) (median: 5.24 ng/L) and tris(2-ethylhexyl) phosphate (TEHP) (median: 10.8 ng/L) dominated in the wet and dry seasons, respectively. Other OPEs varied considerably in concentrations over time, related to their physical and chemical properties, environmental factors (e.g., precipitation and temperature), and varied applications. Furthermore, the significant correlations of individual OPEs suggest their shared utilization, emission sources, and environmental behaviors. Spatially, there was no significant difference (P > 0.05) among the Σ9OPEs concentrations in water samples from different sites (inlet, reservoir, outlet, and tributary) of the reservoirs. Additionally, the concentrations of OPEs in reservoir water samples could be linked to industrial development, economic conditions, and population density. OPEs in the reservoir pose low ecological risks (RQ < 0.1), except for EDHPP and TEHP, which present median ecological risks (RQ = 0.54 and 0.38, respectively). Future studies could investigate more OPEs and their joint effects with other organic pollutants, as well as survey the chemical reactions and degradation pathways of OPEs in different environmental matrices to assess their potential ecotoxicity more comprehensively.

Community-level risk assessments on organophosphate esters in the sediments from the Bohai Sea of China based on multimodal species sensitivity distributions coupled with the equilibrium partitioning method

Organophosphate esters (OPEs), increasingly used as alternatives to brominated flame retardants, are ubiquitous in the global aquatic environment. Despite their potential toxicological impact on ecosystems, community-level risk assessments for OPEs in sediments remain scarce. This study investigated OPE occurrences and composition characteristics in the Bohai Sea's sediments and appraised both individual and joint ecological risks posed by characteristic OPE homologs using ten commonly used species sensitivity distribution (SSD) models, integrating acute-to-chronic conversion and phase equilibrium partitioning. OPEs were detected across all sediment samples, with total concentrations ranging from 0.213 ng/g dry weight (dw) to 91.1 ng/g dw. The predominant congeners included tri-n-butyl phosphate (TnBP), triisobutyl phosphate (TiBP), tri(2-ethylhexyl) phosphate, tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), tris(1, 3-dichloro-2-propyl) phosphate (TDCIPP), and triphenylphosphine oxide. Best-fit SSD models varied among TnBP, TiBP, TCEP, TCPP, and TDCIPP, demonstrating Sigmoid, Burr III, Sigmoid, Burr III, and Burr III, respectively. The same parametric model demonstrated variability in the fitting process for different OPE congeners, which also happened to the fitting results of ten parametric models for the same specific characteristic congener, underscoring the necessity of employing multiple models for precise community-level risk assessments. Hazard concentrations for a 5% cumulative probability were 0.116 mg/L, 2.88 mg/L, 1.30 mg/L, 1.44 mg/L, and 1.85 mg/L for each respective congener. The resulting risk quotients (RQ) and overall hazard index (HI) were selected as criteria to assess the individual and joint ecological risks of OPEs in sediments from the Bohai Sea, respectively. RQ and HI were both below 0.1, indicating a low risk to the local ecosystems. Multi-model SSD analysis could provide refined data for community-level risk evaluation, offering valuable insights for the development of evidence-based environmental standards and pollution control strategies.

Influence of watershed characteristics and human activities on the occurrence of organophosphate esters related to dissolved organic matter in estuarine surface water

Organophosphate esters (OPEs) are widespread in aquatic environments and pose potential threats to ecosystem and human health. Here, we profiled OPEs in surface water samples of heavily urbanized estuaries in eastern China and investigated the influence of watershed characteristics and human activities on the spatial distribution of OPEs related to dissolved organic matter (DOM). The total OPE concentration ranged from 22.3 to 1201 ng/L, with a mean of 162.6 ± 179.8 ng/L. Chlorinated OPEs were the predominant contaminant group, accounting for 27.4–99.6 % of the total OPE concentration. Tris(2-chloroisopropyl) phosphate, tris(1,3-dichloro-2-propyl) phosphate, and tributyl phosphate were the dominant compounds, with mean concentrations of 111.2 ± 176.0 ng/L, 22.6 ± 21.5 ng/L, and 14.8 ± 14.9 ng/L, respectively. Variable OPE levels were observed in various functional areas, with significantly higher concentrations in industrial areas than in other areas. Potential source analysis revealed that sewage treatment plant effluents and industrial activities were the primary OPE sources. The total OPE concentrations were negatively correlated to the mean slope, plan curvature, and elevation, indicating that watershed characteristics play a role in the occurrence of OPEs. Individual OPEs (triisobutyl phosphate, tris(2-butoxyethyl) phosphate, tris(2-chloroethyl) phosphate, and tricresyl phosphate) and Σalkyl-OPEs were positively correlated to the night light index or population density, suggesting a significant contribution of human activity to OPE pollution. The co-occurrence of OPEs and DOM was also observed, and the fluorescence indices of DOM were found to be possible indicators for tracing OPEs. These findings can elucidate the potential OPE dynamics in response to DOM in urbanized estuarine water environments with intensive human activities.

Matrix solid-phase dispersion extraction of organophosphorus flame retardants in soil based on response surface methodology

Organophosphorus flame retardants (OPFRs) are widely used in commercial products owing to their exceptional flame-retarding and plasticizing properties. However, OPFRs are also well recognized as emerging persistent organic pollutants (POPs) because of their environmental persistence, biological concentration, and potential toxicity. Thus, the accurate detection of OPFRs in environmental media is critical for analyzing their fate, transport, and ecological risk. However, very few OPFR detection methods are currently available, and the types of OPFRs detected may vary from site to site. In this study, matrix solid-phase dispersion extraction (MSPD), a simple, rapid, and versatile technique for preparing solid, semisolid, liquid, and viscous samples, was combined for the first time with gas chromatography-tandem mass spectrometry (GC-MS/MS) to analyze 10 OPFRs in soil, namely, tripropyl phosphate (TPrP), tri-n-butyl phosphate (TnBP), tri-iso-butyl phosphate (TiBP), tris(2-chloroisopropyl) phosphate (TCIPP), tris(2-chloroethyl) phosphate (TCEP), tris(1,3-dichloro-2-propyl) phosphate (TDCPP), triphenyl phosphate (TPHP), 2-ethylhexyl diphenyl phosphate (EHDPP), triphenylphosphine oxide (TPPO), and trimethylphenyl phosphate (TCP). The GC-MS/MS system was equipped with a Bruker-5MS capillary column coupled with a triple quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode. Prior to detection, a mixed standard solution was fortified with 10 ng of13C-PCB208 as an internal standard. The optimal conditions under which MSPD could achieve high selectivity for OPFRs were determined. In addition, single-factor analysis was used to examine the influence of the sorbent (i. e., C18, PSA, Florisil, GCB, and multiwalled carbon nanotubes (MWCNTs)) as well as the dosage, type, and volume of the eluent on the extraction efficiency of the method for the 10 OPFRs. When GCB and ethyl acetate were used as the adsorbent and solvent, respectively, during elution, high extraction recoveries for the OPFRs were achieved. Optimization via response surface methodology (RSM) was adopted to further analyze the impact of three key factors, namely, the adsorbent dosage, eluent volume, and grinding time, as well as their interactions, on OPFR recoveries. Under the optimal conditions of 0.3 g of GCB as the adsorbent, 10 mL of ethyl acetate as the eluent, and 5 min of grinding time, the relative average recovery of the OPFRs was 87.5%. Furthermore, the 10 OPFRs showed good linear relationships under five concentration gradients, with correlation coefficients greater than 0.998. The limits of detection (LODs) and quantification (LOQs) were calculated as signal-to-noise ratios (S/N) of 3 and 10, respectively, and found to be in the ranges of 0.006-0.161 and 0.020-0.531 ng/g, respectively. The performance of the proposed method was verified by determining the recoveries and relative standard deviations (RSDs) of the OPFRs in soils spiked at low, medium, and high levels (10, 20, and 100 ng/g, respectively). The recoveries of the OPFRs ranged from 70.4% to 115.4%, with RSDs ranging from 0.7% to 6.7%. Compared with the conventional accelerated solvent extraction (ASE) method, MSPD presents higher efficiency, simpler operation, and less solvent requirements. The developed method was applied to determine OPFRs in soil samples collected from different sites in Suzhou, including an electronics factory, an auto-repair factory, a paddy field, and a school field. The results revealed that the contents of OPFRs in the soils from the electronics and auto-repair factories were significantly higher than those in the soils from the paddy and school fields. The main pollutants in the soil samples collected from the electronics and auto-repair factories were TCIPP, TPPO, TCEP, and TDCPP. Moreover, the contents of these compounds were 5.30, 4.44, 4.54, and 4.20 ng/g, in soils from the electronics factory and 2.70, 3.93, 7.60, and 5.04 ng/g, in soils from the auto-repair factory. To the best of our knowledge, this study is the first to determine high concentrations of TPPO in industrial soils. Thus, the combination of MSPD and GC-MS/MS adopted in this study can provide useful insights into the detection of the 10 OPFRs in soil.

Characteristics, sources, bio-accessibility, and health risks of organophosphate esters in urban surface dust, soil, and dustfall in the arid city of Urumqi in China

Sixty-eight paired samples of urban surface dust and soil as well as four samples of atmospheric dustfall were collected from the arid city of Urumqi in Northwest China. Thirteen organophosphate esters (OPEs) in these samples were analyzed for the characteristics, sources, bio-accessibility, and health risks of OPEs. The studied OPEs were widely detected in the urban surface dust, soil, and dustfall, with Σ13OPEs (total concentration of 13 OPEs) of 1362, 164.0, and 1367 ng/g, respectively, dominated by tris(2-chloroethyle) phosphate (TCEP), tri(2-chloroisopropyl) phosphate (TCiPP), tri(1, 3-dichloroisopropyl) phosphate (TDCiPP) and tris(2-butoxyethyl) phosphate (TBOEP), TBOEP and tri(2-ethylhexyl) phosphate (TEHP), and TCEP, TCiPP, TBOEP, triphenyl phosphate and TEHP, respectively. The low and high frequency magnetic susceptibility of surface dust and urban soil might indicate the pollution of OPEs in them. Elevated levels of the Σ13OPEs in the surface dust and urban soil were found in the west, south, and northeast of Urumqi city. The total deposition flux of dustfall-bound 13 OPEs ranged from 86.5 to 143 ng/m2/day, with a mean of 105 ng/m2/day. OPEs in the surface dust and urban soil were associated with the emissions of indoor and outdoor products containing OPEs, the dry and wet deposition of atmosphere, and the emissions of traffic. Trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tri-isobutyl phosphate, TCEP, TCiPP, TDCiPP, and TBOEP in surface dust and urban soil had relatively high bio-accessibility. The bio-accessibility of OPEs was mainly affected by the physio-chemical properties of OPEs. The non-cancer and cancer risks of human exposure to OPEs in surface dust and urban soil were relatively low or negligible. The current research results may provide scientific supports for prevention and control of pollution and risks of OPEs.

Screening of organophosphorus flame retardant residues in rice by QuEChERS-gas chromatography-quadrupole time-of-flight mass spectrometry

Organophosphorus flame retardants (OPFRs) have emerged as good alternatives to brominated flame retardants, the use of which is globally restricted. In this study, a screening method based on QuEChERS-gas chromatography-quadrupole time-of-flight mass spectrometry (GC-Q-TOF/MS) was established for the determination of 21 OPFRs in rice. First, full scan (scanning range, m/z 50-450) was performed with a mixed standard solution of the 21 OPFRs (0.1 μg/g) by GC-Q-TOF/MS. The fragmentation pathways of these OPFRs were then investigated to explore their cleavage fragments, the interrelationships among fragments, and the possible cleavage modes of alkylated, chlorinated, and aromatic OPFRs. The retention times, isotopic abundance ratios, and molecular formulas of the characteristic fragments as well as the exact mass of the compounds were obtained to establish a mass spectral library of the OPFRs. Rice samples were extracted and purified by the QuEChERS method, and 0.5% formate acetonitrile solution was used as the extraction solvent; 4 g of magnesium sulfate, 1 g of sodium chloride, 0.5 g of disodium hydrogen citrate, and 1 g of sodium citrate as the extraction-salt combination; and 50 mg of primary secondary amine (PSA), 50 mg of octadecylsilane (C18), and 150 mg of magnesium sulfate as the purification materials. The chromatographic separation of the 21 OPFRs was completed within 16 min under optimized temperature program conditions on the DB-5MS UI column. The screening parameters were optimized, and a full scan of the samples was performed under the following conditions: number of characteristic fragment ions ≥2; accurate mass window=±2×10-5 (±20 ppm); retention time deviation=±0.2 min, and ion abundance deviation<20%. The developed method was applied to the screening 21 OPFRs in the samples. The results indicated that the matrix interference was greatly reduced by decreasing the extraction accurate mass window, thereby improving the signal-to-noise ratio of the analytes. The targets were extracted from the matrix interference and background noise using deconvolution software, which improved the match between the target compounds and the mass spectral library. The detection rates of alkyl and aromatic OPFRs increased by 22% and 25%, respectively, when the spiking level was increased from 2 to 10 ng/g. Among the chlorinated OPFRs, only tris(2-chloroisopropyl) phosphate (TCIPP) was not detected at a spiking level of 2 ng/g, indicating that chlorinated OPFRs could be identified even at low concentrations. The characteristic ions of the detected compounds matched those of the home-made mass spectral library well, indicating that the practical application of the home-made mass spectral library. The established screening method was applied in the determination of OPFRs in rice samples from different regions in China. A total of 11 OPFRs were detected, among which trimethyl phosphate (TMP), tri-iso-butyl phosphate (TiBP), and tris(3,5-dimethylphenyl) phosphate (T35DMPP) had the highest detection rates. These results indicate that these three OPFRs are widely used and can easily come into contact with rice samples through various routes. Differences in the types of OPFRs detected in the actual samples may be related to the types of OPFRs produced in local factories. OPFRs can be detected in rice samples by the developed GC-Q-TOF/MS screening method, which is helpful for the identification of OPFRs in complex matrix samples.

Aerobic degradation of parent triisobutyl phosphate and its metabolite diisobutyl phosphate in activated sludge: Degradation pathways and degrading bacteria

Although organophosphate esters (OPEs) degradation has been widely studied, the degradation of their metabolites is always ignored. Triisobutyl phosphate (TiBP), a typical alkyl-OPEs, is of emerging concern because of its potential ecotoxicity in the environment. This study provides comprehensive understanding about the degradation of TiBP and one of its metabolites, diisobutyl phosphate (DiBP) using activated sludge (AS). The results showed that TiBP and DiBP were degraded mainly through hydrolysis, dehydrogenation, and hydroxylation. The degradation kinetics indicated that DiBP had similar transformation rates to its parent TiBP in AS, highlighting the importance of metabolite DiBP study. Dehydrogenase, hydroxylase, phosphotriesterase, phosphodiesterase, and phosphomonoesterase played an important role in contributing to TiBP and its metabolites degradation via enzyme activity analysis. Besides, the expression of genes encoding these enzymes in bacteria and the relative abundance change of bacterial populations indicated that Sphingomonas and Pseudomonas may be the degrading bacteria of TiBP and Pseudomonas may be the main degrading bacteria of DiBP. This study provides new perspectives for metabolite DiBP and its parent TiBP degradation. It highlights that the formation and degradation of metabolites must be considered into the future researches.

Triisobutyl phosphate biodegradation by enriched activated sludge consortia: Degradation mechanism and bioaugmentation potential

This study investigated the ability of activated sludge (AS) to biodegrade triisobutyl phosphate (TiBP) after acclimation in an AS bioreactor by adding 50 mg/L TiBP. The bioreactor significantly increased the biotransformation rate of TiBP (2.15–12.7 d−1) over two months of acclimation. Seven transformation products (TPs) of TiBP were identified by high-resolution mass spectrometry, and hydrolysis, hydroxylation and dehydrogenation were the major biodegradation pathways of TiBP. TiBP degradation solutions at 0, 3, 7, and 10 h showed significantly toxic effects on zebrafish embryos, while the toxicity of TiBP degradation solutions at 24 h significantly decreased. Pseudomonas was inferred to be a specific bacterial population in the TiBP metabolic microbial consortium (TMMC) that degrades TiBP (p < 0.001). When TMMC (0.5, 1, and 2 gss/L) was introduced into AS, the TiBP biotransformation rates (1.97, 2.05, and 2.26 d−1 at 1.0 mg/L TiBP, and 0.09, 0.11, and 0.83 d−1 at 30.0 mg/L TiBP) were significantly enhanced compared to the control (0.31 and 0.07 d−1) without TMMC inoculation. In general, this study provides new insights into the key species populations that accelerate TiBP degradation and promote the development of TiBP reduction biotechnology in WWTPs.

Safe and sustainable by design: A computer-based approach to redesign chemicals for reduced environmental hazards

Persistency of chemicals in the environment is seen a pressing issue as it results in accumulation of chemicals over time. Persistent chemicals can be an asset in a well-functioning circular economy where products are more durable and can be reused or recycled. This objective can however not always be fulfilled as release of chemicals from products into the environment can be inherently coupled to their use. In these situations, chemicals should be designed for degradation. In this study, a systematic and computer-aided workflow was developed to facilitate the chemical redesign for reduced persistency. The approach includes elements of Essential Use, Alternatives Assessment and Green and Circular Chemistry and ties into goals recently formulated in the context of the EU Green Deal. The organophosphate chemical triisobutylphosphate (TiBP) was used as a case study for exploration of the approach, as its emission to the environment was expected to be inevitable when used as a flame retardant. Over 6.3 million alternative structures were created in silico and filtered based on QSAR outputs to remove potentially non-readily biodegradable structures. With a multi-criteria analysis based on predicted properties and synthesizability a top 500 of most desirable structures was identified. The target structure (di-n-butyl (2-hydroxyethyl) phosphate) was manually selected and synthesized. The approach can be expanded and further verified to reach its full potential in the mitigation of chemical pollution and to help enable a safe circular economy.

Occurrence and dry deposition of organophosphate esters in atmospheric particles above the Bohai Sea and northern Yellow Sea, China

Levels of eleven organophosphate esters (OPEs) were measured in particle phase atmospheric samples collected at Bohai Sea and northern Yellow Sea in China. The concentration of ∑11OPEs in atmospheric particles ranged from 426 to 3933 pg/m3, with the mean concentration of 1412 pg/m3. Tris(1-chloro-2-propyl) phosphate (TCPP) and triphenyl-phosphine oxide (TPPO) were the most abundant OPE congeners measured, and the individual concentrations of trimethyl phosphate (TMP), tri-iso-butyl phosphate (TiBP), tri-n-butyl phosphate (TnBP), tris(1,3-dichloro-2-propyl) phosphate (TDCP), triphenyl phosphate (TPhP), 2-ethylhexyl diphenyl phosphate (EHDPP), TPPO and tri-m-cresyl phosphate (TMTP) in atmospheric particles above the Bohai Sea were higher than those above the northern Yellow Sea. The estimated atmospheric dry deposition fluxes ranged from 202 to 1869 ng/m2/day. Up to 18.3 ± 12.5 ton/year of OPEs can be loaded to the Bohai Sea.

Atmospheric deposition, seasonal variation, and long-range transport of organophosphate esters on Yongxing Island, South China Sea

The South China Sea (SCS), surrounded by developing countries/regions with a huge consumption of flame retardants, is generally contaminated by organophosphate esters (OPEs). However, studies on the occurrence, deposition and long-range atmospheric transport (LRAT) process over the SCS of OPEs compounds are still limited. In this work, 10 OPEs were measured in 100 atmospheric samples collected from Yongxing Island (YXI) in the SCS. The total OPEs concentrations ranged from 1508 to 1968 pg/m3 with 28.6–1416.9 pg/m3 in gas and 95.2–1066.2 pg/m3 in particle partition. The three chlorinated OPEs are present at higher concentrations than the other seven non-chlorinated OPEs. Most OPEs had clear seasonal variations that followed the order: spring>summer≈winter>autumn except for tri-isobutyl phosphate (TIBP) and tris-(2-ethylhexyl) phosphate (TEHP). The particle-bound fraction of the total OPEs had little seasonal variations with a mean value of 0.35. Comparing J-P model and Koa model, it was found that the gas/particle partition in the study area was in non-equilibrium condition. LRAT, controlled by seasonal wind direction, was the predominated factor that led to the seasonal variations of OPEs on YXI. The average daily deposition flux of total OPEs was 13.0 ng/m2 with an annual total deposition of 15.06 g.

Development and validation of a multi-pollutant method for the analysis of polycyclic aromatic hydrocarbons, synthetic musk compounds and plasticizers in atmospheric particulate matter (PM2.5)

Exposure to atmospheric particulate matter (PM) associated pollutants is a global concern due to the risk posed in human health after inhalation. In this study, a simple and sensitive multi-residue method is developed for the analysis of 50 organic pollutants, comprising 18 polycyclic aromatic hydrocarbons (PAHs), 12 phthalate esters (PAEs), 12 organophosphorus flame retardants (OPFRs), 6 synthetic musk compounds (SMCs) and 2 bisphenols in PM2.5 samples. The method consists of three cycles of ultrasonic assisted solvent extraction and vortex (UASE + vortex), followed by a vortex-assisted dispersive solid phase extraction (d-SPE) clean-up and a final determination step by using programmed temperature vaporization-gas chromatography-tandem mass spectrometry (PTV-GC-MS/MS). Experimental conditions concerning clean-up adsorbents (alumina, silica gel and Florisil®) and filters (glass fibre, PTFE and nylon), as well as PTV-GC-MS/MS conditions were studied. In addition, the use of SRM (selected reaction monitoring) mode in MS-MS, as well as matrix-matched calibration together with labelled subrogate standards, resulted in successfully validation results for most of the compounds due to the high sensitivity, minimization of matrix effects and recovering losses compensation. The proposed method was validated in terms of linearity, limits of detection and quantification (LODs and LOQs), analytical recoveries by analysing a spiked composite sample (PM2.5) at three spiking levels and intra-day and inter-day precision. Moreover, an urban particulate matter standard reference material (SRM 1648a) was analysed to assess PAHs determination accuracy. Furthermore, applicability of the method was proved by analysing 12 PM2.5 samples from an industrial area. Among all studied pollutants, bisphenol A (BPA) was the most predominant with an average concentration of 5000 pg m−3, followed by bis(2-ethylhexyl) phthalate (DEHP) and diisobutyl phthtalate (DiBP) with 1990 pg m−3 and 632 pg m-3, respectively. Concerning OPFRs, average concentrations between 345 – 253 pg m−3 were found for triphenyl phosphine oxide (TPPO), tris(chloropropyl) phosphate (TCPP), tri-iso-butyl phosphate (TiBP) and tris(2-butoxyethyl) phosphate (TBOEP). Finally, the highest PAHs levels were found for 5-6 ring-number PAHs (Σ5-6 rings PAHs) with an average concentration of 2680 pg m−3, while only 2 SMCs were quantitated accounting for 17.5 pg m−3 by average.

Determination of 16 organophosphate esters in human blood by high performance liquid chromatography-tandem mass spectrometry combined with liquid-liquid extraction and solid phase extraction

人体体液中有机磷酸酯(OPEs)浓度的测定对于了解人体OPEs的暴露水平以及评估人体健康风险具有重要意义。然而,目前的研究大多数集中于尿液中OPEs代谢物含量的分析测定,将其作为人体OPEs暴露的生物标志物,而对人体血液中OPEs的分析研究较少,仅有的少量研究涉及的OPEs种类有限。该研究在优化前处理过程(固相萃取,SPE)和色谱分离的基础上,建立了人体血液中16种OPEs的超高效液相色谱-串联质谱(UPLC-MS-MS)测定方法。血液样品经过乙腈摇床萃取后,经ENVI-18 SPE小柱净化,然后采用Acquity UPLC BEH C18色谱柱,以甲醇/5 mmol/L的乙酸铵水溶液为流动相进行梯度洗脱对目标物进行分离,最后进行LC-MS/MS测定。质谱分析采用电喷雾正离子模式电离,多重反应监测模式测定,内标法定量。在优化的检测条件下,16种OPEs的检出限为0.0038~0.882 ng/mL。除磷酸三甲酯(TMP)外,其余15种OPEs在3个浓度水平的血液基质加标回收率为53.1%~126%,相对标准偏差为0.15%~12.6%。样品的基质效应检测发现,4种OPEs存在明显的基质抑制,选用合适的同位素内标进行定量,可以部分消除基质影响。该方法样品前处理简单,灵敏度高,适用于人体血液样品中OPEs阻燃剂的测定。15个人体血液样本分析结果表明,OPEs的总浓度范围为1.50~7.99 ng/mL,其中8种OPEs的检出率均高于50%,磷酸三异丁酯(TiBP)、磷酸三(2-氯乙基)酯(TCEP)和磷酸三(1-氯-2-丙基)磷酸酯(TCIPP)为主要的OPEs,表明人体存在较为普遍的OPEs暴露,应该引起关注。

EXTRACTION OF METAL IONS BY 4-BENZOYL- OR 4-(3-NYTROBENZOYL-1-HEXYL- 3-METHYL-2-PYRAZOLINE-5-ONES

The extraction properties of solutions of 4-benzoyl- and 4- (3-nitrobenzoyl) -1-hexyl-3-methyl-2-pyrazolin-5-ones in chloroform were studied. The pH dependence of the degree of extraction is S-shaped. Ions Cu2+, Pb2+, Zn2+, Ni2+, Co2+, Mn2+, Cd2+, Ca2+, Mg2+ are extracted in the form of complexes with the ratio M (II): reagent determined by the equilibrium shift method equals to 1: 2. A lower equilibrium pH than the initial value indicates a cation-exchange extraction mechanism. The introduction of an electronegative nitro group into the benzoyl fragment of the reagent led to a shift in the pH50 values of the extraction of metal ions in a more acidic region. The presence of a correlation between the values of the Klopman hardness parameters of the above metal cations and extraction pH50 values was shown. The influence of the nature of the solvent on the extraction of zinc ions was studied. The addition of polar isopentanol to the extractant shifts the pH of the metal extraction to a more acidic region. In order to increase the pH50 value of zinc extraction, the solvents are arranged in a row: 30% isopentanol in CHCl3 &lt; benzene &lt; xylene &lt; toluene &lt; chloroform &lt; dichloroethane. The introduction of additional neutral electron-donating hydrophobic organic compounds into the extract: 1-hexyl-3-methyl-2-pyrazolin-5-one, triisobutyl phosphate, trioctylphosphine oxide significantly increases the values of the partition coefficients of zinc. The observed synergistic effect is explained by the formation of a coordinatively unsaturated intracomplex compound of zinc with aroylpyrazolone, in which the free coordination sites are filled with neutral reagent molecules. In this case, water is replaced and due to the increased hydrophobicity of the complex, an increase in extraction occurs. Confirmation of the formation of a coordination-unsaturated zinc complex is a close to unity value of the slope of the decimal logarithm of the metal distribution constant for pH.

Comparison of receptor models for source identification of organophosphate esters in major inflow rivers to the Bohai Sea, China

A better understanding of the sources of organophosphate esters (OPEs) is a prerequisite for OPE control and the establishment of related environmental policies. Sources of OPEs in 35 major inflow rivers to the Bohai Sea of China were quantitatively analyzed using three effective receptor models (principal component analysis-multiple linear regression (PCA-MLR), positive matrix factorization (PMF), and Unmix) in this paper. The similarities and differences in results from PCA-MLR, PMF, and Unmix were discussed in depth. All three models well predicted the spatial variability of the total concentrations of nine OPEs (triethyl phosphate, tri-n-butyl phosphate, triisobutyl phosphate, tri (2-ethylhexyl) phosphate, tri (2-chloroethyl) phosphate, tris(1-chloro-2-propyl) phosphate, tris(1,3-dichloro-2-propyl) phosphate, triphenyl phosphate, and triphenylphosphine oxide) (∑9OPEs) (r2 = 0.90–0.96, p = 0.000) and explained 98.4%–101.2% of the observed ∑9OPEs. The predicted ∑9OPEs values from each pairwise model were significantly correlated (r2 = 0.88–0.91, p = 0.000). Three OPE sources were extracted by all three models: rigid and flexible polyurethane foam/coating, cellulosic/acrylic/vinyl polymer/unsaturated polyester, and polyvinyl chloride, contributing 49.9%, 29.7%, and 20.5% by PCA-MLR, 57.9%, 28.6%, and 13.5% by PMF, and 47.9%, 30.8%, and 22.4% by Unmix to the ∑9OPEs, respectively. PMF was recommended as the preferred receptor model for analyzing OPE sources in water during the monitoring period because of its optimal performance.

In vitro oxidative stress, mitochondrial impairment and G1 phase cell cycle arrest induced by alkyl-phosphorus-containing flame retardants

Phosphorus-containing flame retardants (PFRs) have been frequently detected in various environmental samples at relatively high concentrations and are considered emerging environmental pollutants. However, their biological effects and the underlying mechanism remain unclear, especially alkyl-PFRs. In this study, a battery of in vitro bioassays was conducted to analyze the cytotoxicity, oxidative stress, mitochondrial impairment, DNA damage and the involved molecular mechanisms of several selected alkyl-PFRs. Results showed that alkyl-PFRs induced structural related toxicity, where alkyl-PFRs with higher logKow values induced higher cytotoxicity. Long-chain alkyl-PFRs caused mitochondrial and DNA damage, resulting from intracellular reactive oxygen species (ROS) and mitochondrial superoxide overproduction; while short-chain alkyl-PFRs displayed adverse outcomes by significantly impairing mitochondria without obvious ROS generation. In addition, alkyl-PFRs caused DNA damage-induced cell cycle arrest, as determined by flow cytometry, and transcriptionally upregulated key transcription factors in p53/p21-mediated cell cycle pathways. Moreover, compared to the control condition, triisobutyl phosphate and trimethyl phosphate exposure increased the sub-G1 apoptotic peak and upregulated the p53/bax apoptosis pathway, indicating potential cell apoptosis at the cellular and molecular levels. These results provide insight into PFR toxicity and the involved mode of action and indicate the mitochondria is an important target for some alkyl-PFRs.

The extraction of gallium from chloride solutions by emulsion liquid membrane: Optimization through response surface methodology

Emulsion liquid membrane was used to extract gallium from a chloride medium. The influence of several critical parameters including, carrier concentration, surfactant concentration, the ratio of the internal phase to the membrane, agitation speed and their interactions on gallium recovery were investigated. A response surface methodology based on a Box-Behnken design was used to find out optimum conditions and determine the interaction effects of parameters. The liquid membrane including a diluent (kerosene), a surfactant (sorbitan monooleate), a carrier (tri-isobutyl phosphate), and 0.1 M sulfuric acid as the stripping solution was used. Maximum gallium recovery (94.6%) were obtained at the carrier concentration of 5.8% (v/v), the surfactant concentration of 3.2% (v/v), the ratio of the internal phase to the membrane of 1.1 and the agitation speed of 245 rpm. The gallium recovery increased with an increase in the level of the investigated parameters, and after reaching the optimum conditions, it decreased. A predictive model was proposed to predict the gallium recovery from the chloride solution by emulsion liquid membrane. The results indicated that the gallium can be effectively recovered from the chloride solution using emulsion liquid membrane with tri-butyl phosphate (TBP) as a carrier.

Organophosphate esters in human serum in Bohai Bay, North China

Organophosphate esters (OPEs), as a class of emerging flame retardant and plasticizers, have attracted particular attention due to their ubiquitous existence in the environment and potential effects on human health. Here, we investigated the levels of OPEs in human serum and examined the role of demographic variables on the body burden of such compounds. Of 11 OPEs screened, 8 were detected in human serum samples collected from a population (n = 89) in Bohai Bay, North China. The ∑OPE concentrations ranged from 4.7 to 948ng/g lipid weight (lw), with a median concentration of 243ng/g lw. Tris(2-chloroethyl)phosphate (TCEP) was identified as the most abundant OPEs with a median concentration of 214ng/g lw. The concentrations of the triphenyl phosphate (TPhP) in older adults were higher than those in young adults (p < 0.05), and lower concentrations of tri-iso-butyl phosphate (TIBP) were observed in female samples compared to males. Furthermore, significant differences were observed in tri-n-propyl phosphate (TPrP) concentrations between urban and rural residence groups (p < 0.05). This study provides important information on the accumulation potential of OPEs in human bodies and suggests the need for further investigation to understand the potential human health risk.

Occurrence and distribution of organophosphate esters in sediment from northern Chinese coastal waters

Organophosphate esters (OPEs) are used as flame retardants and plasticizers in many consumer products. Owing to OPEs’ toxicity, exposure of organisms in aquatic ecosystems is a concern. Information that pertains to the occurrence and distribution of OPEs in marine aquatic environment, however, is scarce. In this study, concentrations and profiles of 14 OPE triesters were determined in sediment collected in coastal waters (Bohai Sea and East China Sea) of northern China. The total concentrations of OPEs (ΣOPEs) in surface sediment were in the range of 1.76–49.9 (median: 9.13) ng/g dry weight (dw), which were comparable to or lower than the range of concentrations reported for surface sediments worldwide. Tris(2-chloro-propyl) phosphate (TCIPP), tris(2-chloroethyl) phosphate (TCEP), tri-isobutyl phosphate (TiBP), and tri-n-butyl phosphate (TnBP) were the predominant OPEs found in surface sediment, collectively accounting for 81% of the total concentrations. ΣOPE concentrations in sediment core (range: 8.58–169, median: 31.6 ng/g dw) were generally higher than those found in surface sediment. The vertical distribution of OPEs in sediment core showed a gradual increasing trend in concentrations during the past decade.