Trimethyl Phosphate Research Articles

Toward reversible wide-temperature Zn storage by regulating the electrolyte solvation structure via trimethyl phosphate

The introduction of TMP changes the coordination environment of Zn 2+ to reshape the hydrogen bond network of water. A novel strategy is established to regulate Zn 2+ -solvation shell, restraining vanadium dissolution, suppressing Zn dendrite formation and contributing to uniform deposition of Zn 2+ . • A novel Zn 2+ -solvation shell is formed via trimethyl phosphate. • Zn symmetrical battery exhibits an ultralong cyclic lifespan for 7000 h at 1 mA cm −2 . • The cathode dissolution and self-discharge of battery are efficiently suppressed. • Zn|VO 2 (B) cell possesses 97.86% capacity retention after 1200 cycles at 1 A·g −1 (0 °C). The wide-scale application of zinc-ion batteries (ZIBs) is largely restricted by dendrite formation, hydrogen evolution corrosion and capacity fading, caused by the coordinated H 2 O within the Zn 2+ -solvation shell as well as reactive active water in the bulk electrolyte. Here, one green and flame-retardant additive, trimethyl phosphate (TMP) is introduced into aqueous electrolyte systems, contributing to Zn 2+ -solvation shell reshaping and promoting the stability hydrogen bonding network of H 2 O. The strategy is significant in suppressing water-induced side reactions and dendrite growth, enabling an ultralong cycling lifespan of 7000 h at 1 mA·cm −2 and 0.5 mAh·cm −2 in Zn symmetrical cell. In addition, Zn|VO 2 (B) full cells with TMP addition exhibit an ultralong cyclic performance for 1200 cycles at 1 A·g −1 with 97.86% capacity retention even at 0 °C, which contributes to taking a step closer to commercial application. This work demonstrates the feasibility of developing electrolytes for practical ZIBs that integrate safety, sustainability and wide-temperature applications.

Ultralow-water-activity electrolyte endows vanadium-based zinc-ion batteries with durable lifespan exceeding 30 000 cycles

Vanadium-based cathodes with high specific capacity have attracted wide attention in aqueous zinc ion batteries. The main barriers of the development of vanadium-based cathodes are vanadium dissolution, structure degradation, instability of cathode electrolyte interlayer (CEI) and parasitic reactions in aqueous electrolyte. In this work, for the first time, we propose a new type of ultralow-water-activity electrolyte that tackles all these problems. Our design is realized by the introduction of pioneering inert electrolyte filler (trimethyl phosphate). It is discovered that highly concentrated ZnCl2H2O clusters are surrounded by this electrolyte filler, reaching the lowest free solvation water composition (2.5%) reported so far. The ultralow water activity significantly inhibits parasitic reactions and vanadium dissolution, boosting the achievement of the highest columbic efficiency (99.98%). The biggest bottleneck of vanadium-based cathodes dissolution and water shuttle has been broken through by stable CEI. As a proof of concept, the V6O13 cathode demonstrates exceptional stability of 99.43% capacity retention after 3 000 cycles at 1 A g−1, and sets a new record for cycle life of 30 000 cycles (capacity retention of 90.34% at 10 A g−1) in zinc ion batteries, even reaching the level of supercapacitors (∼100 000 cycles).

Exploring Trimethyl-Phosphate-Based Electrolytes without a Carbonyl Group for Li-Rich Layered Oxide Positive Electrodes in Lithium-Ion Batteries.

Li-rich layered oxides (LLOs) are one of the most attractive next-generation positive electrode materials as a result of their high energy density and low cost. However, the deterioration of cycling stability observed in LLOs remains one of the fundamental obstacles to commercialization. Carbonate-based electrolytes reacting with oxygen radicals evolved from the lattice of LLOs is the chief cause of their poor cyclability. Herein, we construct no carbonyl group, trimethyl phosphate (TMP)-based electrolytes with a fluorinated ether co-solvent and apply them to investigate the electrochemical behaviors of LLO batteries. These electrolytes can capture active oxygen species; the initial reversible capacity of cells reaches 295.5 mAh g-1; and the capacity retention remains 96.7% after 100 cycles. In contrast, the capacity retention of cells using carbonate-based electrolytes is only 54.7% after 60 cycles. These results would provide the scientific basis and theoretical support for building electrolytes of LLOs with high properties in the future.

Improved interfacial compatibility between flame-retardant electrolytes and graphite electrodes by tuning the solvation structure of Li+

Conventional electrolytes with flammability and volatility may incur severe safety issues, which are impeding the application of lithium batteries on a large scale. Flame-retardant solvents are introduced into the electrolytes to enhance the security performance, while the battery electrochemical performance is compromised due to incompatibility between these solvents and graphite (Gr) anode. In this work, a flame-retardant electrolyte prepared by trimethyl phosphate (TMPa), lithium difluoro(oxalato)borate (LiDFOB) and fluoroethylene carbonate (FEC) could be expected to solve the dilemma via regulating the solvation structure of Li+ to suppress the co-intercalation effect of TMPa with Li+ and alleviate the compatibility issues of interface caused by the continuous reduction of LiDFOB. The formation mechanism of the solid electrolyte interface (SEI) at the graphite electrode was analyzed to explore the intrinsic reaction of the electrolyte at the electrode interface. The 300-cycle capacity retention of Li|Gr cell at 0.5C reaches 97.48 %, and the deposition and stripping performance of the Li|Li symmetric cell is also significantly improved. Such Li+ solvation structure modification provides a new idea for fire-extinguishing electrolyte design and helps to promote the industrialization of safe and eco-friendly electrolytes.

Nonflammable dual-salt localized high-concentration electrolyte for graphite/LiNi0.8Co0.1Mn0.1O2 lithium-ion batteries: Li+ solvation structure and interphase

Trimethyl phosphate (TMP) is the most promising safe solvent for lithium-ion battery (LIB) electrolyte because of the nonflammability, oxidation stability and low cost, but its application is hindered by the incompatibility with the graphite anode. Herein, a nonflammable localized high-concentration electrolyte with ordinary concentration (1 mol L−1) is developed for graphite/LiNi0.8Co0.1Mn0.1O2 (Gr/NCM811) LIBs with TMP/1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether (TTE) binary solvents. The origin of the capacity decay is elucidated with a comprehensive investigation of the Li+ solvation structure and electrode/electrolyte interface. On this basis, a dual-salt strategy of lithium hexafluorophosphate (LiPF6)/lithium difluoro(oxalato)borate (LiDFOB) is employed, and a stable cycling of the Gr/NCM811 full cell is achieved with upper voltages of both 4.3 V and 4.6 V. The optimization of the nonflammable TMP/TTE electrolyte demonstrates that Li+ solvation structure and interphase are respectively the thermodynamic and kinetic factors for the side reactions of the electrolyte occurring at the electrode: the Li+ solvation structure determines the reduction and oxidation tolerances of the electrolyte in thermodynamics, while the interface determines the decomposition rate in kinetics.

Controlling Intermolecular Interaction and Interphase Chemistry Enabled Sustainable Water-tolerance LiMn2 O4 ||Li4 Ti5 O12 Batteries.

Solid electrolyte interphase (SEI) formation and H2 O activity reduction in Water-in-Salt electrolytes (WiSE) with an enlarged stability window of 3.0 V have provided the feasibility of the high-energy-density aqueous Li-ion batteries. Here, we extend the cathodic potential of WiSE by rationally controlling intermolecular interaction and interphase chemistry with the introduction of trimethyl phosphate (TMP) into WiSE. The TMP not merely limits the H2 O activity via the strong interaction between TMP and H2 O but also contributes to the formation of reinforced SEI involving phosphate and LiF by manipulating the Li+ solvation structure. Thus, water-tolerance LiMn2 O4 (LMO)||Li4 Ti5 O12 (LTO) full cell with a P/N ratio of 1.14 can be assembled and achieve a long cycling life of 1000 times with high coulombic efficiency of >99.9 %. This work provides a promising insight into the cost-effective practical manufacture of LMO||LTO cells without rigorous moisture-free requirements.

Controlling Intermolecular Interaction and Interphase Chemistry Enabled Sustainable Water‐tolerance LiMn2O4||Li4Ti5O12 Batteries

AbstractSolid electrolyte interphase (SEI) formation and H2O activity reduction in Water‐in‐Salt electrolytes (WiSE) with an enlarged stability window of 3.0 V have provided the feasibility of the high‐energy‐density aqueous Li‐ion batteries. Here, we extend the cathodic potential of WiSE by rationally controlling intermolecular interaction and interphase chemistry with the introduction of trimethyl phosphate (TMP) into WiSE. The TMP not merely limits the H2O activity via the strong interaction between TMP and H2O but also contributes to the formation of reinforced SEI involving phosphate and LiF by manipulating the Li+ solvation structure. Thus, water‐tolerance LiMn2O4 (LMO)||Li4Ti5O12 (LTO) full cell with a P/N ratio of 1.14 can be assembled and achieve a long cycling life of 1000 times with high coulombic efficiency of >99.9 %. This work provides a promising insight into the cost‐effective practical manufacture of LMO||LTO cells without rigorous moisture‐free requirements.

Zn metal anodes stabilized by an intrinsically safe, dilute, and hydrous organic electrolyte

Rechargeable Zn batteries hold great promise for large-scale energy storage applications but their reversibility is limited by non-compact and dendritic Zn deposition along with interfacial parasitic reactions in conventional electrolytes. Herein, we report an intrinsically safe, dilute, and hydrous organic electrolyte by coupling hydrated Zn(BF4)2 salt with trimethyl phosphate (TMP) solvent for highly reversible Zn batteries, without the need of concentrated electrolyte strategies. The formulated 1 m Zn(BF4)2/TMP enables spatially compact, dendrite-free, and corrosion-free Zn electrodeposition even at high areal capacity (5 and 10 mAh cm−2) using a pressure-free electrolytic cell. Moreover, the hydrous organic electrolyte with low water activity expands the electrochemical window to 3 V (versus Zn2+/Zn) and in-situ forms a protective ZnF2-Zn3(PO4)2-rich interphase on Zn. The resultant Zn electrode achieves long-term cycling over 4200 h with a superhigh cumulative plating capacity of 10500 mAh cm−2 under 5 mA cm−2 in Zn//Zn cell and exhibits high efficiency of 99.5% over 600 cycles in Zn//Cu cell (1 mA cm−2; 1 mAh cm−2). Moreover, this electrolyte supports the stable operation of a full Zn//V2O5·nH2O battery by significantly suppressing cathode dissolution. This work would enlighten the design of hydrous organic electrolytes for practical Zn batteries.

(Digital Presentation) Electrochemical Behavior of Ionic Liquid Modified of Lithium Bis(fluorosulfonyl)Imide Based Electrolyte for Lithium-Ion Batteries

The high efficient energy storage, lithium-ion batteries (LIBs) is accounted as one of the most important storage devices to facilitate the transition of renewable energy conversion. The electrolyte component is the most important in deciding the capacity of LIBs. Lithium bis(fluorosulfonyl)imide (LiFSI) is recently considered as promising conducting electrolyte salt for LIBs because it shows enabling high voltage, high energy density, long cycle life, and accelerates the fast-charging Li-ion batteries. Generally, Additionally, LiFSI and LiPF6 based electrolyte are used in the most of commercial LIBs. Last few years, LiFSI is regarded as an alternative electrolyte to the classical LiFP6 due to its high ionic conductivity, good thermal stability, and HF free nature. In this work, the controlled mixing of ionic liquids (ILs) (imidazolium salts and pyridinium salts) in LiFSI electrolyte was carried out to enhance the ionic conductivity, thermal stability, viscosity, and solubility in organic solvents. The ILs modified LiFSI electrolyte was prepared by adding a constant 1.0 M LiFSI and varying the concentration of ILs from 5 to 20% volume in trimethyl phosphate (TMP). After the modification by ILs, the ionic conductivity of LiFSI electrolyte (10.623 mS/cm) was considerably increased as compared to LiFSI only. The flammability test of electrolyte revealed that ILs modified LiFSI electrolyte was non-flammable, indicating excellent stability in any circumstances. The prepared ILs modified LiFSI electrolyte was used to fabricate coin cell LIBs using double-coated side electrodes (both CMS graphite/Li-NCM (5:2:3) and CMS graphite/LiFePO4). From GCD analysis, the fabricated LIBs with ILs modified LiFSI electrolyte showed a significant improvement in the charging/discharging ability as compared to commercial LIBs with LiPF6 electrolyte. This study manifests that the modification of LiFSI by novel ILs would be promising to achieve highly efficient liquid electrolytes for high performance LIBs.

Atomic Layer Deposition of Metal Phosphates

Since the introduction of lithium iron phosphate (LFP) as an electrode material for Li-ion batteries (LIB’s), metal phosphates in general have become increasingly important. The strong covalency of the P-O bonds typically results in a very good thermal and structural stability, which is one of the main reasons for the success of LFP as a LIB electrode. However, the applications of these metal phosphates are multi-fold. Apart from LIB’s, they have been proven to be promising towards e.g. electrocatalytic water splitting, biocompatible coatings or even as protective coatings for luminescent materials.With these applications in mind, the research towards the deposition of these materials also becomes increasingly important. Atomic Layer Deposition (ALD) has emerged as a deposition technique with unique nanotailoring capabilities compared to conventional methods, particularly owing to its high thickness and compositional control. Down-scaling micro-electronic devices according to Moore’s law has already increased interest in the unique capabilities ALD can offer. However, in addition to using ALD for the fabrication of such devices, it can also offer a unique way to create model systems to gain a fundamental insight for a broad range of applications.From this it can be seen why the combination of both research fields, i.e. ALD of metal phosphates, is gaining a lot of interest over the past years. Since the first metal phosphate has been deposited in 1969, a big challenge has been to find a suitable phosphate precursor. Today, the most popular choice proves to be trimethyl phosphate, i.e. TMP. It has allowed for the deposition of a variety of phosphates (e.g. aluminium phosphate, lithium phosphate, iron phosphate, etc.), but more research is required to further extent this research field. To stimulate this research, a comprehensive study on the currently (un)available literature is needed. It would e.g. allow to get a better understanding on the effect of different phosphate precursors and/or various reaction mechanisms during ALD can be better understood, as well as the potential applications of these materials (such as lithium ion battery applications). As such a study on ALD of metal phosphates was so far not yet available, we hope that this work can create a view that is of interest towards various scientific fields, and help to guide future thin film researchers.

Non-target screening and risk assessment of organophosphate esters (OPEs) in drinking water resource water, surface water, groundwater, and seawater.

By use of an integrated target, suspect, and non-target screening strategy, we investigated occurrence and spatial distribution of organophosphate esters (OPEs) in four types of water (drinking water resource water, surface water, groundwater, and seawater) collected from Jiangsu Province (China) in 2021 (n=111). Eighteen out of 23 target OPEs were detectable at least once in these analyzed samples, and the total concentrations (Σ18OPEs) of OPEs in various water samples exhibited a descending order following as: groundwater (67026ng/L)>surface water (35803ng/L)>drinking water resource water (21055ng/L)>seawater (17820ng/L). The highest concentration detected in groundwater may be ascribed to pollution from surrounding factories. Among the target OPEs, triethyl phosphate (TEP), tris(chloroethyl) phosphate (TCEP), and tris (1-chloro-2-propyl) phosphate (TCIPP) were the most abundant congeners with the average concentrations of 407ng/L, 143ng/L, and 475ng/L, respectively. Besides of 18 target OPEs, we further identified 17 suspect OPEs (3 of them were fully identified by authentic standards) on the basis of in-house suspect screening OPE database, and 2 non-target organophosphates (OPs) on the basis of feature fragments. One of these 2 non-target OPs was fully identified as bis(2-chloroethyl) 2-chloroethylphosphonate (B2CE2CEPP) by matching the retention time and MS/MS data with authentic standard, and the other one was preliminarily identified as 2,4,8,10-tetra-tert-butyl-6-methoxydibenzo[d,f][1,3,2]dioxaphosphepin-6-one (TTBMDBDOPPO). We also observed that B2CE2CEPP shared a similar structure with TCEP, suggesting that they may have similar toxicological characteristics and commercial sources. The ecological and human health risk assessments indicated that all OPEs posed a low or negligible ecological risk to aquatic organisms (algae, crustacean, and fish), and negligible risk to human health except for trimethyl phosphate (TMP) in drinking water resource water.

Validated quantitative 31P NMR spectroscopy for positional isomeric impurity determination in L-α-glycerylphosphorylcholine (L-α-GPC)

In this study a quantitative 31P nuclear magnetic resonance (31P NMR) spectroscopy method was described to determine positional isomeric impurity β-GPC in commercial products of L-α-GPC. The samples were dissolved in D2O and trimethyl phosphate (TMP) was selected as an internal calibrant. The measurements were performed on a Bruker 500 MHz spectrometer and the spectra were recorded under optimized process conditions. A good linear relationship was constructed for β-GPC in the range of 62.7–528.0 µg·mL−1, i.e. 0.03–0.25 % (w/w %, in relative to L-α-GPC) with a correlative coefficient of 0.9996. The limit of quantification (LOQ) and limit of detection (LOD) were 62.7 µg·mL−1 and 20.9 µg·mL−1 with signal to noise of 3 and 10, respectively. The spiked recoveries were in the range of 98.17–99.78 % with the relative standard deviation (RSD %) less than 1.0 %. Therefore, it could be supposed that the 31P NMR was a promising alternative method for sensitive determination of β-GPC for strict quality control of L-α-GPC.

Non‐Flammable Ester Electrolyte with Boosted Stability Against Li for High‐Performance Li Metal Batteries

AbstractIn traditional non‐flammable electrolytes a trade‐off always exists between non‐flammability and battery performance. Previous research focused on reducing free solvents and forming anion‐derived solid‐electrolyte interphase. However, the contribution of solvated anions in boosting the stability of electrolyte has been overlooked. Here, we resolve this via introducing anions into Li+ solvation sheaths using anions with similar Gutmann donor number (DN) to that of solvents. Taking trimethyl phosphate fire‐retardant (DN=23.0 kcal mol−1) and NO3− (DN=22.2 kcal mol−1) as an example, NO3− is readily involved in the Li+ solvation sheath and reduces the polarity of solvent. This results in boosted stability of electrolyte against Li. The developed non‐flammable electrolyte has low viscosity, high ionic conductivity and is low cost. The reversibility of Li‐Cu cell was improved to 99.49 % and the lifespan of practical LMBs was extended by >100 %.

Non-Flammable Ester Electrolyte with Boosted Stability Against Li for High-Performance Li Metal Batteries.

In traditional non-flammable electrolytes a trade-off always exists between non-flammability and battery performance. Previous research focused on reducing free solvents and forming anion-derived solid-electrolyte interphase. However, the contribution of solvated anions in boosting the stability of electrolyte has been overlooked. Here, we resolve this via introducing anions into Li+ solvation sheaths using anions with similar Gutmann donor number (DN) to that of solvents. Taking trimethyl phosphate fire-retardant (DN=23.0 kcal mol-1 ) and NO3 - (DN=22.2 kcal mol-1 ) as an example, NO3 - is readily involved in the Li+ solvation sheath and reduces the polarity of solvent. This results in boosted stability of electrolyte against Li. The developed non-flammable electrolyte has low viscosity, high ionic conductivity and is low cost. The reversibility of Li-Cu cell was improved to 99.49 % and the lifespan of practical LMBs was extended by >100 %.

Carrageenan‐vermiculite‐dimethyl methyl phosphate ternary hybrid hydrogels for firefighting

AbstractAn eco‐friendly and bio‐based ternary hybrid hydrogel consisting of carrageenan, vermiculite, and dimethyl methyl phosphate (DMMP) was prepared through a facile one‐pot method. Rheological tests showed that this ternary hybrid hydrogel was a power‐law fluid. The formulation of the ternary hybrid hydrogel was also screened, and the optimal formulation was found to be the ternary hybrid hydrogel containing 1 wt% carrageenan, 2 wt% DMMP, and 4 wt% vermiculite. Firefighting experiments showed that the ternary hybrid hydrogel could stop the chain reaction and rapidly reduce the temperature of combustion. Compared to water, the extinguishing time of the ternary hybrid hydrogel was shortened by 46.6%, and the volume consumed was reduced by 43.3%. The superior fire extinguishing efficiency of the ternary hybrid hydrogel could be attributed to the combined effect of each component: carrageenan provides viscosity, making the hydrogel firmly cover the burning surface; DMMP works as a free radical scavenger that can stop chain reactions; and vermiculite acts as a barrier layer, which helps to insulate air and heat and prevent resurgence. This work provides an environmentally‐friendly, cost‐effective, and bio‐based hybrid hydrogel for firefighting.

Improving Compatibility between Trimethyl Phosphate and Graphite Anodes by Preconstructing a Stable Solid Electrolyte Interphase Film

The electrolyte additive of trimethyl phosphate (TMP) shows a good flame-retardant property for lithium-ion batteries (LIBs) comprising nonaqueous carbonate solvents. However, TMP is not conducive to cycle performance because of its poor compatibility with graphite anodes. Herein, a stable solid electrolyte interphase (SEI) film on the graphite surface is preconstructed by cycling the Li||graphite half-cell with the 1.5 M lithium difluoro(oxalato)borate (LiDFOB)-ethylene carbonate (EC)/dimethyl carbonate (DMC) electrolyte for five cycles. The as-generated stable SEI film is relatively rich in LiF and lithium oxalate, which helps to restrain the cointercalation of Li+-TMP and improves the compatibility between TMP and the graphite anode. As a result, the modified Li||graphite cell enables a good flame-retardant property and excellent electrochemical performance, even if the 0.7 M LiDFOB-EC/DMC/TMP(40%) electrolyte is used in the subsequent cycles. This study emphasizes the importance of constructing a stable SEI film and provides a reference method for designing safe and practical electrolytes for LIBs.

Occurrence, spatial variation, seasonal difference, and ecological risk assessment of organophosphate esters in the Yangtze River, China: From the upper to lower reaches

A comprehensive contamination profile of organophosphate esters (OPEs) in the Yangtze River in China has not yet been characterized. In this study, we investigated the occurrence, spatial variation, and seasonal difference of 18 selected OPEs in surface water samples of the Yangtze River mainstream. To characterize the contamination profile of the OPEs, we collected 144 Yangtze River water samples from 72 sampling sites in December 2020 and June 2021. Four alkyl-OPEs [trimethyl phosphate, triethyl phosphate (TEP), tributyl phosphate, and tris(2-butoxyethyl) phosphate (TBOEP)] and three halogenated OPEs [tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCIPP), and tris(1,3-dichloro-2-propyl) phosphate] were the most frequently detected target compounds (>95%). TCIPP (median: 34.6 ng/L), TEP (median: 26.2 ng/L), and TCEP (median: 17.9 ng/L) were the most abundant compounds, while the median values of the others were below 10 ng/L. Additionally, the concentrations of most OPEs gradually/dramatically increased from upstream to downstream Yangtze River. Notably, the median concentration of summed OPEs in Shanghai (415 ng/L; downstream) was approximately ten times higher than that in Qinghai (45.7 ng/L; upstream). Urban sampling sites had significantly or slightly higher concentrations of most OPEs than rural sampling sites. Moreover, the OPE concentrations in the river water differed between the winter and summer. The concentrations of summed OPEs (median: 117 vs. 106 ng/L), summed alkyl-OPEs (67.0 vs. 45.8 ng/L; p < 0.05), and summed aryl-OPEs (0.48 vs. 0.17 ng/L; p < 0.05) were slightly or significantly higher in December than those in June; nevertheless, summed halogenated OPEs were slightly higher in June (62.2 vs. 50.2 ng/L) than that in December. Compared with previously reported data for OPEs in other major rivers worldwide, the Yangtze River water had relatively lower concentrations of the OPEs than those in the rivers of developed countries and regions. Ecological risk assessment suggested that tris(2-ethylhexyl) phosphate and TCEP posed relatively high risks (RQ: 1.01 and 0.98, respectively) at the maximum concentration, and TBOEP posed a moderate risk (RQ: 0.25). This is the first study to comprehensively characterize the contamination profile of the Yangtze River by the OPEs.

On the Electron-Induced Reactions of (CH3)AuP(CH3)3: A Combined UHV Surface Science and Gas-Phase Study.

Focused-electron-beam-induced deposition (FEBID) is a powerful nanopatterning technique where electrons trigger the local dissociation of precursor molecules, leaving a deposit of non-volatile dissociation products. The fabrication of high-purity gold deposits via FEBID has significant potential to expand the scope of this method. For this, gold precursors that are stable under ambient conditions but fragment selectively under electron exposure are essential. Here, we investigated the potential gold precursor (CH3)AuP(CH3)3 using FEBID under ultra-high vacuum (UHV) and spectroscopic characterization of the corresponding metal-containing deposits. For a detailed insight into electron-induced fragmentation, the deposit’s composition was compared with the fragmentation pathways of this compound through dissociative ionization (DI) under single-collision conditions using quantum chemical calculations to aid the interpretation of these data. Further comparison was made with a previous high-vacuum (HV) FEBID study of this precursor. The average loss of about 2 carbon and 0.8 phosphor per incident was found in DI, which agreed well with the carbon content of the UHV FEBID deposits. However, the UHV deposits were found to be as good as free of phosphor, indicating that the trimethyl phosphate is a good leaving group. Differently, the HV FEBID experiments showed significant phosphor content in the deposits.

Simultaneous measurement of six biomarkers of dichlorvos in blood by ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry

A protocol was developed, via a data-dependent high-resolution tandem mass spectrometry (ddHRMS/MS), to detect six biomarkers of dichlorvos in its metabolites and blood adducts of butyrylcholinesterase and albumin without using standard synthetic peptides. Firstly, the adducts of dimethoxy phosphonate (DMP-BChE) and the aged adducts of methoxy phosphonate (MxP-BChE) were isoloated by immunomagnetic separation (IMS), and then digested to DMP-nonapeptide and MxP-nonapeptide by pepsin. The dichlorvos and its metabolites (Trimethyl phosphate, Dimethyl phosphate) were analyzed in the supernatant of IMS treatment after protein precipitation. The precipitate was digested by pronase to phosphorylated tyrosine (DMP-Tyr), which were quantified by ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry (UPLC-MS). The linearity of detector response of all biomarkers was studied in their respective ranges, and the correlation coefficients (R2) were all greater than 0.9981. The limits of detection (LOD) and limits of quantification (LOQ) were 0.2–10 ng/mL and 0.5–20 ng/mL, respectively. The recoveries of the six biomarkers were 78.6–110.0 %, matrix effect were 64.1–106.8 %. Inter- and intra-assay precision had coefficients of variation of ≤13.2 % and ≤9.7 %, respectively. In addition, MxP- BChE, DMP-Tyr, TMP, DMP and DDVP were detected in the blood of three cases who died from DDVP poisoning, but DMP- BChE was not detected in all of them, which may be caused by the instability of DMP- BChE and its easy aging to form MxP-BCHE.

Development and validation of skeletal/global mechanisms describing TMP-based flame inhibition

Phosphorus-based chemical compounds such as trimethylphosphate (TMP) and dimethylmethylphosphonate (DMMP) are widely used as fire suppressants. The detailed chemical kinetic mechanism by Jayaweera et al. [1] is frequently used to describe the flame inhibition process. The elementary reaction steps can be categorised into inhibitor molecule decomposition steps and radical recombination steps. The present work shows that the inhibitor decomposition process can be adequately represented by a single irreversible step for TMP. Subsequently, graph-based mechanism reduction techniques and sensitivity analysis are employed to extract the key catalytic inhibition reactions. The resultant skeletal kinetic mechanism consists of 4 species and 7 reactions. The present work also proposes a global mechanism containing 3 species and 3 reactions. In the global model, flame inhibition is described by a 2-step model. These models are validated in premixed and diffusion flame environments. Excellent agreement with the experimental measurements and detailed model predictions are obtained. Development of the skeletal/global models reduces the computational time by around 82% compared to the detailed model.