Contamination of dairy products with tris(2,4-di-tert-butylphenyl) phosphite and implications for human exposure.

Tris(2,4-di-tert-butylphenyl) phosphite (AO168), an organophosphite antioxidant, can be oxidized to tris(2,4-di-tert-butylphenyl) phosphate (AO168 = O) during the production, processing, and application of plastics. AO168 = O can be further transformed to bis(2,4-di-tert-butylphenyl) phosphate and 2,4-di-tert-butylphenol. Here, we discovered the contamination of AO168 and its transformation products in dairy products for the first time. More samples contained AO168 (mean concentration: 8.78 ng/g wet weight [ww]), bis(2,4-di-tert-butylphenyl) phosphate (mean:11.1 ng/g ww) and 2,4-di-tert-butylphenol (mean: 46.8 ng/g ww) than AO168 = O (mean: 40.2 ng/g ww). The concentrations of AO168 and its transformation products were significantly correlated, and differed with the packaging material and storage conditions of the product. Estimated daily intakes (EDIs) of AO168 and its transformation products were calculated. Although the overall dietary risks were below one, transformation products accounted for 96.7% of the total hazard quotients. The high-exposure EDIs of total AO168 were above the threshold of toxicological concern (300 ng/kg bw/day), and deserve continual monitoring.

Considerations when deriving compound-specific limits for extractables and leachables from pharmaceutical products: Four case studies.

Leachables from pharmaceutical container closure systems are a subset of impurities that present in drug products and may pose a risk to patients or compromise product quality. Extractable studies can identify potential leachables, and extractables and leachables (E&Ls) should be evaluated during development of the impurity control strategy. Currently, there is a lack of specific regulatory guidance on how to risk assess E&Ls; this may lead to inconsistency across the industry. This manuscript is a cross-industry Extractables and Leachables Safety Information Exchange (ELSIE) consortium collaboration and follow-up to Broschard et al. (2016), which aims to provide further clarity and detail on the conduct of E&L risk assessments. Where sufficient data are available, a health-based exposure limit termed Permitted Daily Exposure (PDE) may be calculated and to exemplify this, case studies of four common E&Ls are described herein, namely bisphenol-A, butylated hydroxytoluene, Irgafos® 168, and Irganox® 1010. Relevant discussion points are further explored, including the value of extractable data, how to perform route-to-route extrapolations and considerations around degradation products. By presenting PDEs for common E&L substances, the aim is to encourage consistency and harmony in approaches for deriving compound-specific limits.

In-process prepared deep eutectic solvent based homogeneous liquid-liquid microextraction for the determination of irgaphos 168 and irganox 1010 in polypropylene packed drinks.

In situ synthesis of a deep eutectic solvent and homogeneous liquid-liquid microextraction performed in a narrow bore tube was developed for efficient extraction of irgaphos 168 and irganox 1010 in doogh and water samples packed in polypropylene packages. First, pH of the aqueous sample solutions containing the analytes is adjusted at 9. Then a hydrogen bond acceptor (choline chloride) and a hydrogen bond donor (oleic acid) are dissolved in the solution and vortexed to obtain a homogeneous solution. The solution is filled into a narrow bore tube, in which its bottom was clogged by a septum. Then hydrochloric acid solution is injected into the solution by a syringe. The tube is placed in an ultrasonic bath. During this step, the droplets of choline chloride:oleic acid deep eutectic solvent are produced. The method indicated high enrichment factor (435 for irgaphos 168 and 488 for irganox 1010), low limits of detection (0.03 and 0.09 ng/mL for irgaphos 168 and irganox 1010, respectively) and quantification (0.13 and 0.29 ng/mL for irgaphos 168 and irganox 1010), good recovery (74 and 83% for irgaphos 168 and irganox 1010, respectively), and satisfactory repeatabilities (relative standard deviations ≤12%) can be obtained using the developed method.

Highly Selective Fluorescent Sensing of Phosphite through Recovery of Poisoned Nickel Oxide Nanozyme.

Phosphorus is a key element responsible for eutrophication, and its measurement and speciation is a critical topic in analytical chemistry. Most research efforts have been devoted to detecting phosphate (P(V)), while few reports on phosphite (P(III)) are available, making it difficult for sensor-based understanding of the phosphorus cycle. This study presents a fluorescent "turn-on" sensor for quantitative and highly selective analysis of phosphite based on the different coordination strength of N and P lone-pair electrons toward nickel oxide (NiO). A few N-containing compounds (mainly Good's buffers) were screened as inhibitors for the oxidase-like activity of NiO nanoparticles for the oxidation of Amplex red (AR). HEPES was found to be most effective for inhibiting the formation of fluorescent resorufin, the oxidation product of AR. Among various phosphorus-, arsenic-, selenium-, and sulfur-containing species, along with various cations, phosphite was the only one that could restore the activity, likely due to its stronger affinity with the surface, and it is not an inhibitor. Under the optimum condition, the sensor detected P(III) up to 1 mM with a detection limit of 1.46 µM. The phosphite analysis with recovery rates ranged from 74.2 ± 2.6% to 107.5 ± 0.5% in real water and biological samples, suggesting the potential applicability of this sensor.

In situ sampling and speciation method for measuring dissolved phosphite at ultratrace concentrations in the natural environment.

Phosphite (P+III) is of emerging chemical interest due to its importance within the global phosphorus cycle. Yet, to date, precise/accurate measurements of P+III are still lacking due to the inherent analytical challenges linked to its instability/ease of oxidation and ultra-trace concentration. Here, we present the first in-situ sampling and speciation analysis method, for dissolved P+III, using the diffusive-gradients-in-thin-films (DGT) technique, combined with capillary-column-configured-dual-ion-chromatography (CC-DIC). Method optimization of the DGT elution regime, to simultaneously maximize desorption efficiency and CC-DIC sensitivity, along with the characterization of diffusion coefficients for P+III, were undertaken before full method validation. Laboratory-performance testing confirmed DGT-P+III acquisition to be independent of pH (3.0-10.0) and ionic strength (0-500 mM). The capacity for P+III was 45.8 µg cm-2, while neither P+V (up to 10 mg L-1) nor As+V (up to 1 mg L-1) impacted the DGT-P+III measurement. This novel method's functionality stems from the herein confirmed speciation preservation and double pre-concentration of P+III, resulting in quantification limits as low as 7.44 ng L-1 for a 3-day deployment. Applications of this method in various terrestrial/aquatic environments were demonstrated and simultaneous profiles of P+III and P+V across a sediment-water interface were captured at mm resolution in two contrasting redox-mesocosm systems.

Sulphate radical generation through interaction of peroxymonosulphate with Co(II) for in-line sample preparation aiming at spectrophotometric flow-based determination of phosphate and phosphite in fertilizers.

An advanced oxidative process relying on the interaction of peroxymonosulphate and cobalt(II) was implemented for generating the sulphate radicals in flow analysis, in order to accomplish in-line sample preparation thus improving the spectrophotometric determination of phosphate and phosphite in liquid foliar fertilizers. To this end, a flow-batch system with a heated chamber was designed. The sample was handled twice, with and without the step of phosphite oxidation to phosphate, and the formed orthophosphate was quantified after interaction with the vanadate-molybdate reagent. Phosphite was determined as the difference in analytical signals corresponding to sample handling with and without the oxidation step. Influence of Co(II) on the peroxymonosulphate activation, reagent concentrations and added volumes, acidity, temperature and heating time were investigated like aiming at to improve analytical recovery and measurement repeatability, as well as the and system ruggedness. The 6.6-20.0mgL(-1) P2O5 standards were in-line prepared from a single stock solution. Detection limits were estimated as 0.8 and 0.1mgL(-1) for P2O5 and P-PO4. Twenty-four samples are were run per hour, and results are were in agreement with those obtained by the official procedure.

A derivatization strategy for the detection and identification of volatile trialkylphosphites using liquid chromatography-online solid phase extraction and offline nuclear magnetic resonance spectroscopy.

We demonstrate herein the application of selective derivatization method that converts volatile and labile trialkylphosphites (TAPs) into virtually non-volatile, thermally stable, and UV absorbing derivatives. After simple sample preparation, purification/enrichment of the derivatives was achieved by using high performance liquid chromatography (HPLC) coupled to on-line post column solid phase extraction (SPE) system. These derivatives were subjected to (31)P{(1)H} NMR and 1D-selTOCSY experiments. Conclusive identification was achieved on the basis of their HPLC retention time and NMR spectral signatures ( [Formula: see text] , (n)JH-H, and (3)JP-H). This method was tested for the unambiguous identification of a mixture containing low concentrations (∼10µgmL(-1)) of trimethylphosphite (TMP), triethylphosphite (TEP), triisopropylphosphite (TIP), and tributylphosphite (TBP) along with a high concentration of irrelevant background chemicals. It offered a high dynamic range and good detection limit and recovery (>75%) without the need for special NMR probe heads or exotic NMR experiments.

Determination of phosphite in a full-scale municipal wastewater treatment plant.

Phosphite (HPO3(2-), +3), a reduced P species in the P biogeochemical cycle, was monitored in a full-scale municipal wastewater treatment plant (MWTP) that uses an anaerobic/anoxic/aerobic-membrane bioreactor (A(2)/O-MBR) technology for treating mixed wastewater (56% industrial wastewater and 44% domestic wastewater) from June 2013 to May 2014. Wastewater samples were collected from influent after having gone through the fine grille, anaerobic tank, anoxic tank, and aerobics tank, respectively. The final stage yielded effluent. Results confirmed the presence of phosphite in the MWTP ranging from 4.62 ± 1.00 µg P L(-1) to 34.30 ± 3.49 µg P L(-1) in influent and from 1.15 ± 0.5 µg P L(-1) to 4.42 ± 0.9 µg P L(-1) in effluent. Phosphite accounted for approximately 0.15% to 2.27% of total soluble phosphorus (TSP). During the A(2)/O-MBR process, the average removal of phosphite was 82.41 ± 7.45%. The anaerobic biological treatment removed the most phosphite from wastewater in this study. Spatially, phosphite concentrations decreased gradually as the wastewater treatment process progressed. Seasonally, the phosphite concentrations in spring and winter were higher than those in summer and autumn. The phosphite concentration in effluent was of the same order of magnitude as that in nearby natural water, which suggested MWTP effluent may be an important phosphite contributor to the natural water.

Redox chemistry in the phosphorus biogeochemical cycle.

The element phosphorus (P) controls growth in many ecosystems as the limiting nutrient, where it is broadly considered to reside as pentavalent P in phosphate minerals and organic esters. Exceptions to pentavalent P include phosphine--PH3--a trace atmospheric gas, and phosphite and hypophosphite, P anions that have been detected recently in lightning strikes, eutrophic lakes, geothermal springs, and termite hindguts. Reduced oxidation state P compounds include the phosphonates, characterized by C-P bonds, which bear up to 25% of total organic dissolved phosphorus. Reduced P compounds have been considered to be rare; however, the microbial ability to use reduced P compounds as sole P sources is ubiquitous. Here we show that between 10% and 20% of dissolved P bears a redox state of less than +5 in water samples from central Florida, on average, with some samples bearing almost as much reduced P as phosphate. If the quantity of reduced P observed in the water samples from Florida studied here is broadly characteristic of similar environments on the global scale, it accounts well for the concentration of atmospheric phosphine and provides a rationale for the ubiquity of phosphite utilization genes in nature. Phosphine is generated at a quantity consistent with thermodynamic equilibrium established by the disproportionation reaction of reduced P species. Comprising 10-20% of the total dissolved P inventory in Florida environments, reduced P compounds could hence be a critical part of the phosphorus biogeochemical cycle, and in turn may impact global carbon cycling and methanogenesis.

Phosphite-induced changes of the transcriptome and secretome in Solanum tuberosum leading to resistance against Phytophthora infestans.

BACKGROUND: Potato late blight caused by the oomycete pathogen Phytophthora infestans can lead to immense yield loss. We investigated the transcriptome of Solanum tubersoum (cv. Desiree) and characterized the secretome by quantitative proteomics after foliar application of the protective agent phosphite. We also studied the distribution of phosphite in planta after application and tested transgenic potato lines with impaired in salicylic and jasmonic acid signaling. RESULTS: Phosphite had a rapid and transient effect on the transcriptome, with a clear response 3 h after treatment. Strikingly this effect lasted less than 24 h, whereas protection was observed throughout all time points tested. In contrast, 67 secretome proteins predominantly associated with cell-wall processes and defense changed in abundance at 48 h after treatment. Transcripts associated with defense, wounding, and oxidative stress constituted the core of the phosphite response. We also observed changes in primary metabolism and cell wall-related processes. These changes were shown not to be due to phosphate depletion or acidification caused by phosphite treatment. Of the phosphite-regulated transcripts 40% also changed with ß-aminobutyric acid (BABA) as an elicitor, while the defence gene PR1 was only up-regulated by BABA. Although phosphite was shown to be distributed in planta to parts not directly exposed to phosphite, no protection in leaves without direct foliar application was observed. Furthermore, the analysis of transgenic potato lines indicated that the phosphite-mediated resistance was independent of the plant hormones salicylic and jasmonic acid. CONCLUSIONS: Our study suggests that a rapid phosphite-triggered response is important to confer long-lasting resistance against P. infestans and gives molecular understanding of its successful field applications.

LC-MS/MS analytical procedure to quantify tris(nonylphenyl)phosphite, as a source of the endocrine disruptors 4-nonylphenols, in food packaging materials.

Tris(nonylphenyl)phosphite, an antioxidant used in polyethylene resins for food applications, is problematic since it is a source of the endocrine-disrupting chemicals 4-nonylphenols (4NP) upon migration into packaged foods. As a response to concerns surrounding the presence of 4NP-based compounds in packaging materials, some resin producers and additive suppliers have decided to eliminate TNPP from formulations. This paper describes an analytical procedure to verify the "TNPP-free" statement in multilayer laminates used for bag-in-box packaging. The method involves extraction of TNPP from laminates with organic solvents followed by detection/quantification by LC-MS/MS using the atmospheric pressure chemical ionisation (APCI) mode. A further acidic treatment of the latter extract allows the release of 4NP from potentially extracted TNPP. 4NP is then analysed by LC-MS/MS using electrospray ionisation (ESI) mode. This two-step analytical procedure ensures not only TNPP quantification in laminates, but also allows the flagging of other possible sources of 4NP in such packaging materials, typically as non-intentionally added substances (NIAS). The limits of quantification were 0.50 and 0.48 µg dm⁻² for TNPP and 4NP in laminates, respectively, with recoveries ranging between 87% and 114%. Usage of such analytical methodologies in quality control operations has pointed to a lack of traceability at the packaging supplier level and cross-contamination of extrusion equipment at the converter level, when TNPP-containing laminates are processed on the same machine beforehand.

Advanced oxidation of hypophosphite and phosphite using a UV/H2O2 process.

The oxidation of hypophosphite and phosphite in an aqueous solution by an ultraviolet (UV)/H2O2 process was studied in this work. The reactions were performed in a lab-scale batch photoreactor. The effect of different parameters such as H2O2 dosage, H2O2 feeding mode and the initial pH of the solution on the oxidation efficiency of the process was investigated. The results indicated that the UV/H2O2 process could effectively oxidize hypophosphite and phosphite in both synthesized and real wastewater. However, neither H2O2 nor UV alone was able to appreciably oxidize the hypophosphite or phosphite. The best way of feeding H2O2 was found to be 'continuous feeding', which maximized the reaction rate. It was also found that the process presented a wide range of applicable initial pH (5-11). When treating real rinse-wastewater, which was obtained from the electroless nickel plating industry, both hypophosphite and phosphite were completely oxidized within 60 min, and by extending by another 30 min, over 90% of the chemical oxygen demand removal was obtained. Without any additional catalyst, the UV/H2O2 process can oxidize hypophosphite and phosphite to easily removable phosphate. It is really a powerful and environmentally friendly treatment method for the wastewater containing hypophosphite and phosphite.

Monitoring of phosphorus oxide ion for analytical speciation of phosphite and phosphate in transgenic plants by high-performance liquid chromatography-inductively coupled plasma mass spectrometry.

Large amounts of phosphate fertilizers utilized in agriculture and their relatively poor efficiency are of high ecological and economic concern. Therefore, transgenic plants capable of metabolizing phosphite are being engineered. In support of this biotechnological task, analytical speciation of phosphorus in biological tissues is required. In this study, plant extracts were analyzed by liquid chromatography-inductively coupled plasma mass spectrometry at m/z of elemental phosphorus and phosphorus oxide ions. Using polymeric-based anion exchange column and millimolar concentration of nitric acid in potassium phthalate mobile phase (pH 2.5), phosphite and phosphate ions were baseline resolved with retention times 6.95 ± 0.03 and 7.90 ± 0.03 min and with a total chromatographic run time 10 min. The detection limits were 1.58 and 1.74 µg P L(-1) at m/z 47, as compared to 2.18 and 2.04 µg P L(-1) at m/z 31, respectively. The results obtained in real world samples for the two detection modes were in good agreement, yet signal acquisition at m/z 47 enabled better precision without collision/reaction cell (RSD below 2%) as compared to RSD around 4% obtained at m/z 31 using He-pressurized cell (3.5 mL min(-1)).

Phosphite in sedimentary interstitial water of Lake Taihu, a large eutrophic shallow lake in China.

The seasonal occurrence and distribution of phosphite (HPO3(2-), P) in sedimentary interstitial water from Lake Taihu was monitored from 2011 to 2012 to better understand its possible link to P cycle in the eutrophic shallow lake. Phosphite concentrations ranged from < MDL to 14.32 ± 0.19 µg P/kg with a mean concentration of 1.58 ± 0.33 µg P/kg, which accounts for 5.51% total soluble P (TSP(s)) in surficial sediments (0-20 cm). Spatially, the concentrations of sedimentary phosphite in the lake's northern areas were relatively higher than those in the southern areas. Higher phosphite concentrations were always observed in seriously polluted sites. Generally, phosphite in the deeper layers (20-40 cm and 40-60 cm) showed minor fluctuations compared to that in the surficial sediments, which may be associated with the frequent exchange at the sediment-water interface. Phosphite concentrations in surficial or core sediments decreased as spring > autumn > summer > winter. Higher phosphite levels occurred in the areas with lower redox (Eh), higher P contents, and particularly when metal bonded with P to form Al-P(s) and Ca-P(s). Phosphite may be an important media in the P biogeochemical cycle in Lake Taihu and contribute to its internal P transportation.

Triphenyl phosphite, a new allergen in polyvinylchloride gloves.

BACKGROUND: Contact allergy to polyvinylchloride (PVC) gloves has been reported relatively seldom. In spring 2011, 5 of our patients had patch test reactions to PVC gloves. We obtained a collection of PVC raw materials from industrial producers and suppliers of chemical compounds to be patch tested on patients with suspected PVC glove contact allergy. OBJECTIVES: To report the first results of these new test substances. METHODS: The patients were patch tested with the newly obtained test substances, plastics and glues series, and isocyanates and isocyanate prepolymers. We analysed nine PVC glove samples for triphenyl phosphate and its derivatives. RESULTS: Two patients reacted to a technical PVC antioxidant and one of its components, triphenyl phosphite (TPP). Contact allergy to TPP was very strong in 1 patient, and was the main cause of her hand dermatitis, whereas the other patient also had other contact allergies explaining her symptoms. Three patients reacted to their PVC gloves, but the specific allergen was not identified. Six PVC glove samples contained TPP at concentrations of 0.004-0.099%. TPP transforms into triphenyl phosphate during storage. CONCLUSIONS: TPP represents a new allergen in PVC gloves. It was detected in several PVC gloves in fairly high concentrations.

Determination of phosphite in a eutrophic freshwater lake by suppressed conductivity ion chromatography.

The establishment of a sensitive and specific method for the detection of reduced phosphorus (P) is crucial for understanding P cycle. This paper presents the quantitative evidence of phosphite (P, +3) from the freshwater matrix correspondent to the typically eutrophic Lake Taihu in China. By ion chromatography coupled with gradient elution procedure, efficient separation of micromolar levels of phosphite is possible in the presence of millimolar levels of interfering ions, such as chloride, sulfate, and hydrogen carbonate in freshwater lakes. Optimal suppressed ion chromatography conditions include the use of 500 µL injection volumes and an AS11 HC analytical column heated to 30 °C. The method detection limit of 0.002 µM for phosphite was successfully applied for phosphite determination in natural water samples with recoveries ranging from 90.7 ± 3.2% to 108 ± 1.5%. Phosphite in the freshwater matrix was also verified using a two-dimensional capillary ion chromatography and ion chromatography coupled with mass spectrometry. Results confirmed the presence of phosphite in Lake Taihu ranging from 0.01 ± 0.01 to 0.17 ± 0.01 µM, which correlated to 1-10% of the phosphate. Phosphite is an important component of P and may influence biogeochemical P cycle in lakes.

Speciation of phosphorus oxoacids in natural and waste water samples.

Phosphorus is a key nutrient and in natural environments regulates trophic status and consequently water quality. Therefore monitoring of phosphorus content in natural and wastewater is essential. Although several phosphorus species can be found in the environment, the majority of the methods developed are for orthophosphate determination. High performance liquid chromatography (HPLC) coupled with inductively coupled plasma with atomic emission spectroscopy (ICP-AES) has been first used in this study for the speciation of the most common phosphorus oxoanions in aquatic environments: orthophosphate, phosphite, hypophosphite, pyrophosphate and tripolyphosphate. The chromatograms have been obtained by registering the phosphorous 213.618 nm emission intensity variation with time. The pH and the ionic strength of the mobile phase have been the most critical variables of the chromatographic separation. Moreover, methanol addition promotes the elution of the most retained species. Finally, by using ammonium nitrate and a gradient elution, increasing ionic strength and decreasing the pH, the separation has been achieved in 12 min. Limits of detection have been included within the 1-5 mg L(-1) range. The developed methodology has been tested with spiked tap water and effluent water of a wastewater treatment plant (WWTP) obtaining recoveries in the range of 91.5-114.1% for a 20 mg P L(-1) spike concentration.

Elucidating the redox cycle of environmental phosphorus using ion chromatography.

Historically, it was assumed that reactive, inorganic phosphorus present in pristine environments was solely in the form of orthophosphate. However, this assumption contradicts theories of biogenesis and the observed metabolic behavior of select microorganisms. This paper discusses the role of ion chromatography (IC) in elucidating the oxidation-reduction cycle of environmental phosphorus. These methods employ suppressed-IC, coupled with tandem conductivity and electrospray mass spectrometry detectors to identify and quantify phosphorus oxyanions in natural water, synthetic cosmochemical, and biological samples. These techniques have been used to detect phosphite and orthophosphate in geothermal hot springs. Hypophosphite, phosphite, and orthophosphate have been detected in synthetic schreibersite corrosion samples, and termite extract supernatant. Synthetic schreibersite corrosion samples were also analyzed for two poly-phosphorus compounds, hypophosphate and pyrophosphate, and results show these samples did not contain concentrations above the 1.3 and 2.0 µM respective 3σ limit of detection. These methods are readily adaptable to a variety of matrices, and contribute to the elucidation of the oxidation-reduction cycle of phosphorus oxyanions in the environment. In contrast to most studies, these techniques have been used to show that phosphorus actively participates in redox processes in both the biological and geological world.

An enzymatic fluorescent assay for the quantification of phosphite in a microtiter plate format.

A sensitive fluorometric assay for the quantification of phosphite has been developed. The assay uses the enzymatic oxidation of phosphite to phosphate by a recombinant phosphite dehydrogenase with NAD(+) as cosubstrate to produce the highly fluorescent reaction product resorufin. The optimized assay can be carried out in a 96-well microtiter plate format for high-throughput screening purposes and has a detection limit of 0.25 nmol phosphite. We used the method to quantify phosphite levels in plant tissue extracts and to determine phosphite dehydrogenase activity in transgenic plants. The assay is suitable for other biological or environmental samples. Because phosphite is a widely used fungicide to protect plants from pathogenic oomycetes, the assay provides a cost-effective and easy-to-use method to monitor the fate of phosphite following application.

Detection of a nerve agent simulant using single-walled carbon nanotube networks: dimethyl-methyl-phosphonate.

Single-walled carbon nanotube (SWNT) networks were used to detect hazardous dimethyl-methyl-phosphonate (DMMP) gas in real time, employing two different metals as electrodes. Random networks of SWNTs were simply obtained by drop-casting a SWNT-containing solution onto a surface-oxidized Si substrate. Although the electrical responses to DMMP at room temperature were reversible for both metals, the Pd-contacting SWNT network sensors exhibited a higher response and a shorter response time than those of the Au-contacting SWNT network sensors at the same DMMP concentration, due to the stronger interactions between the SWNTs and Pd surface atoms. In Pd-contacting SWNT network sensors, the response increased linearly with increasing DMMP concentration and reproducible response curves were obtained for DMMP levels as low as 1 ppm. These results indicate that SWNT networks in contact with Pd electrodes can function as good DMMP sensors at room temperature with scalable and fast response and excellent recovery.