Presence Of Ammonium Hydroxide Research Articles

Towards a Correlation Between Iron/Cobalt Content, Support Pore Size and Metal Particle Size in Supported Catalysts

AbstractFe−Co‐based catalysts supported on γ‐Al2O3, Aerosil 200 silica and zeolite 4A were prepared by co‐precipitation of the respective nitrates in the presence of ammonium hydroxide. The objective was to demonstrate the influence of Fe/Co mass ratio and support pore size on metal particle size. Catalysts were characterized by thermogravimetric analysis (TGA), X‐ray diffraction (XRD), N2 physisorption, Fourier‐transformed infrared spectroscopy (FTIR), and scanning (SEM) and transmission (TEM) microscopies. It was demonstrated that the minimal presence of Fe was enough to reduce the average particle diameters by half. Increasing Fe content did not cause proportional decreases in the average particle diameter. The support pore diameter probably played a role in the crystallization step of bimetallic and Fe monometallic catalysts, whose particle diameters were similar to those observed for the pores. This phenomenon was not observed for Co monometallic catalysts.

Zaštita ugljeničnog čelika od korozije superhidrofobnim premazom

Under atmospheric conditions at 100% humidity, a surface phase film of moisture is formed on the surface of metals, in which air microimpurities NH3, CO2, H2S, etc. are dissolved and almost completely hydrated with the formation of NH4OH and acids H2CO3 and H2S. The method of potentiodynamic polarization has been used to study the protective efficiency of a superhydrophobic coating on carbon steel in NaCl-based model media simulating saturation of the surface moisture film with carbon dioxide (IV) and/or ammonia under atmospheric conditions. Similar studies were carried out with uncoated electrodes. The superhydrophobic coating was obtained on the basis of laser texturing of the steel surface followed by hydrophobization with fluoroxysilane (wetting angle 165±2°, rolling angle 3±1°). The influence of the duration of exposure of electrodes in solution (0.25 - 168 h) on the kinetics of electrode processes, the rate of steel corrosion and the protective effectiveness of the superhydrophobic coating is considered. It has been shown that the presence of ammonium hydroxide or ammonium carbonate in solution increases the protective effectiveness of the coating compared to a purely chloride medium simulating harsh atmospheric conditions.

Adsorbents development for hydrogen cleanup from ammonia decomposition in a catalytic membrane reactor

Copper-exchanged faujasite (Cu-FAU) zeolites have been investigated in this work as promising adsorbent materials to further purify hydrogen produced via ammonia decomposition in a membrane reactor. Samples have been prepared via ion-exchange procedure using commercially available NaY, HY and 13X zeolites and their performance was evaluated and compared to the one of their parent zeolites. The introduction of copper species in the zeolites framework was demonstrated to enhance the NH3 useful and saturation capacities of the zeolites. However, the Cu-FAU zeolites synthesized in presence of copper(II)nitrate trihydrate and calcined in air showed significant deactivation after a first adsorption/desorption cycle. Samples characterization revealed that this phenomenon can be attributed to dealumination which is on the other hand prevented when ion-exchange procedure occurs in presence of ammonium hydroxide and inert environment is adopted during calcination. The most promising adsorbent material was found to be the one-time ion-exchanged form of zeolite 13X, showing a useful capacity stable at 3.07 ± 0.39 mmol NH3/gsorbent over ten cycles during which saturation was performed with a He/NH3 mixture containing 3000 ppm of NH3 and regeneration was performed in He. As similar performance has been achieved under operating conditions emulating the outlet stream of a membrane reactor for ammonia decomposition, the one-time ion-exchanged form of zeolite 13X can be regarded as a promising adsorbent material to effectively purify NH3-derived H2 produced via ammonia decomposition in a membrane reactor.

Efficient multicomponent processes for synthesis of novel poly-nuclear hetero aryl substituted terpyridine scaffolds: Single crystal XRD study

We studied the synthesis of novel terpyridine scaffolds from poly-nuclear and hetero-aryl aldehydes by the multicomponent condensation reactions with various acetyl pyridine derivatives in the presence of ammonium hydroxide. We have synthesised highly substituted pyridine scaffolds by different poly-nuclear and heterocyclic molecules that are not easily accessed by conventional methods. Comparative studies of two different processes catalysed by potassium hydroxide and pyrrolidine have been performed and presented in this report. The structures of all the newly prepared terpyridine molecules have been well established by preforming various spectral analysis and single crystal XRD studies for selected molecules. This approach addressed some structural miscellany concerns currently facing in photo-luminescent chemistry, and the derived hybrid pyridines could be used as suitable precursors for the synthesis of related photo-luminescent systems. The prepared scaffolds as such and their d-block or f-block metal complexes and coordination polymers may provide an efficient candidate for photo-luminescent chemistry.

Hydrophobic Modification of Glass Surface by Using Sol-Gel Synthesized Glass Powder as A Surface Roughness Promoter

In this study, it was aimed to form a hierarchical surface by using glass powders in the coating solution which was applied to glass surfaces for reducing the surface energy. Glass powders (GP) were synthesized by sol gel method at room temperature in the presence of ammonium hydroxide as an alkali catalyst and ethanol water mixture as solvent. Glass powders were used as additives in the chemical modification material to form rough surfaces for obtaining hydrophobic property on the borosilicate substrates. Two solutions were prepared by using different silane types and three different amounts of glass powders were added to each. Substrates were coated with the prepared coating suspension. The coated samples were heat treated for curing of silane matrix at 110°C for an hour and then washed. The morphology and the size of the particles were visualized by scanning electron microscopy. Water contact angle measurements were carried out to determine the contact angle values and consequent hydrophobic features. 3 different powder ratios were used. Water contact angle values increased by the increasing powder ratio. Water contact angle values were reached to 115° from 20°.

Heatless polyol synthesis of disk-shaped silver particles and the enhanced shape control using tellurium

Despite several studies on the synthesis of silver nanoparticles, the development of an efficient and cost-effective synthesis is still a significant issue in the silver powder industry. Here, we report a simple and energy-efficient synthesis of silver particles, including disk-shaped particles, using a polyol process. This process does not require heating during synthesis, even with the use of ethylene glycol as the reducing agent, resulting in the completion of the entire reaction within a few minutes. The reaction system of this process consists of ammonium hydroxide, hydrogen peroxide, and non-transition metal elements as the catalysts. The presence of ammonium hydroxide during the reaction enabled the oxidation of ethylene glycol to glycolaldehyde without heating. Several non-transition metals were investigated as catalysts to control the shape of the silver particles. Tellurium and tin were determined to be effective catalysts for the formation of silver particles with disk shapes. The sintering behavior and electrical properties of the synthesized silver particles were investigated.

Enhanced visible-light photocatalytic performances of ZnO through loading AgI and coupling piezo-photocatalysis

AgI nanoparticles decorated with ZnO flower-like composites were successfully synthesized via citric acid-induced hydrothermal reaction and subsequent chemical deposition in the presence of ammonium hydroxide. The effects of AgI-loading content and the piezoelectric effect of ZnO were investigated using different technologies. The crystal structures and optical and photocatalytic properties revealed that the AgI particles were successfully loaded on the flower-like ZnO through the directed diffusion process of charge-induced deposition. Results also showed that the band gap of the AgI/ZnO composite located between those of the ZnO and the AgI, which was consistent with the theoretic simulation. The degradation rate of RhB induced by the AgI/ZnO composites was three times larger than that of AgI, and the heterojunction exhibited high photocatalytic degradation efficiency for MO and TC. Besides, the photodegradation efficiency remained high after six times. Radical scavenger experiments implied that e− and h+ played important roles in the photocatalytic process. The photodegradation time was considerably shortened while maintaining increased degradation efficiency after adding ultrasonic vibration due to the rapid separation of carriers caused by the piezo-photocatalysis coupling effect.

Novel Amine-Functionalized Magnesium Oxide Adsorbents for CO2 Capture at Ambient Conditions

• MgO was synthesized using three facile methods • MgO was functionalized with different amines (APTES, DETA and PEI) • APTES-MgO and DETA-MgO adsorbed more than 2 and 1.5 times CO 2 relative to bare MgO • APTES-MgO preserved its full adsorption capacity even after 6 regeneration cycles • Regeneration is carried out using N 2 under mild conditions (30 min, 120 °C, 1 atm) In this study, we synthesized novel magnesium oxide-based adsorbents and utilized them for CO 2 capture at ambient conditions (1 atm, 30 °C). Magnesium oxide (MgO) was synthesized using a facile sol-gel technique starting from magnesium nitrate and ammonium hydroxide, sodium hydroxide or oxalic acid. MgO adsorbent synthesized in the presence of ammonium hydroxide (labeled as MgO-A) showed the highest surface area (350 m 2 /g), which has been correlated with the highest CO 2 adsorption capacity (30 mg/g) relative to those synthesized in the presence of sodium hydroxide (MgO-N) or oxalic acid (MgO-O). The characterization of the MgO samples (MgO-A, MgO-N and MgO-O) using XRD, FTIR, SEM, BET, and elemental analysis revealed that the synthesis route has a significant impact not only on surface area but also on the crystallinity, morphology, and textural properties (surface area, porosity and pore size distribution) of these MgO adsorbents. Nonetheless, the key novelty of the work reported herein is the functionalization of MgO with 3-aminopropyl-triethoxysilane (APTES), diethylenetriamine (DETA) and polyethylenimine (PEI) and their utilization for CO 2 capture at ambient conditions. The functionalization of MgO-A with the three amines significantly altered its characteristics (i.e., crystallinity, morphology, and textural properties). More importantly, the functionalization of MgO-A with APTES and DETA resulted in an increase in CO 2 adsorption from 30 (in the case of the unmodified MgO-A) to 65 and 47.6 mg/g, respectively. These values correspond, respectively, to 0.81 and 1.13 mol CO 2 captured/mol amine loaded on MgO-A. However, the functionalization of MgO-A with the polymeric amine (PEI) caused a significant reduction in the adsorbent surface area, leading to a decrease in CO 2 adsorption. Regeneration studies (using APTES-MgO-A as an example) demonstrated that contacting the spent adsorbent with N 2 gas at 120 °C for a short time can fully restore its original adsorption capacity, suggesting the potential commercial use of APTES-MgO-A for CO 2 capture with a minimal energy requirement.

Photocatalytic Performance of Zinc Ferrite Magnetic Nanostructures for Efficient Eriochrome Black-T Degradation from the Aqueous Environment under Unfiltered Sunlight

Herein, three different types of zinc ferrite (ZnFe2O4) magnetic nanoparticles as photocatalysts were synthesized from iron and zinc sulfate using a co-precipitation method. Tri ethylene glycol (TEG) was utilized as a capping/stabilizing agent in the presence of ammonium hydroxide. The as-prepared nanoparticles were annealed at 400 °C for 4 h followed by acid etching with HCl (for 15 min in I M solution). The thermally treated magnetic nanostructure was subjected to surface modification by treating with 3-aminopropyl (triethoxysilane) 3-(APTES) at 60 °C for 2 h. Various characterization techniques including Fourier transform infrared (FTIR), Brunauer-Emmett-Teller (BET), and X-rays diffraction (XRD) were carried out to examine the structural properties of the pristine and functionalized nanocrystals. XRD pattern assessed the crystalline and nano size of the ZnFe2O4 recording particle sizes of 13.5, 23.3, and 106.5 nm for functionalized, annealed, and pristine ZnFe2O4 nanoparticles, respectively. FTIR spectral analysis corroborated the modifications and functionalization of the samples. BET analysis revealed a surface area of 0.6719 (functionalized), 45.21 (annealed), and 155.38 (pristine nanoparticles). The photocatalytic activity of the prepared nanostructures was investigated for Eriochrome Black T (EBT) dye under the unfiltered sunlight. At optimal reaction parameters, the photocatalytic rates of EBT dye for functionalized, annealed, and blank NP’s were 92, 91, and 83%, respectively. Kinetic models demonstrate that the degradation processes followed pseudo-first-order kinetics. The energies of the band gap in the acidic and basic media, as determined from the Tauc plot, were 2.47 and 2.7 eV, respectively. Taken together, the results showed that newly fabricated nanostructures are considered as promising photocatalysts in degrading organic pollutants for a sustainable environment.

Optical, structural, morphological, and compositional properties of cobalt doped tin oxide (CTO) thin films deposited by modified chemical bath method in alkaline medium

Tin oxide and cobalt doped tin oxide (CTO) thin films were successfully deposited using modified chemical bath method with tin (II) chloride dihydrate and cobalt chloride hexahydrate as precursors for Sn and Co ions respectively, in the presence of ammonium hydroxide as source of oxygen and pH adjuster. The samples obtained were annealed for 4 h at a temperature of 673 K and characterized for optical, structural, morphological and compositional analysis. The films exhibit low absorbance values (0.02–0.31) and low reflectance values (2.14%–20.10%) which varies directly with cobalt ion (Co2+) concentration. The transmittance values (48.64%–96.16%) of the films are high and varies inversely with cobalt ion (Co2+) concentration. The refractive index varies directly with increasing cobalt ion concentration and ranges from 2.60 to 1.49 for doped film and 1.34 for the undoped SnO2. Extinction coefficient of the films varies directly with cobalt ion concentration. The films have wide band gap, (2.90 eV–2.72 eV for doped films and 3.05 eV for undoped SnO2 thin film). Structural analysis revealed that the films are of tetragonal rutile phase of SnO2 with mineral name of cassiterite and confirmed that the grain sizes of the deposited films range from 10.99 nm to 9.40 nm. The dislocation density ranged between 8.28×10−3(line/nm2) and 11.32×10−3(line/nm2) while the microstrain obtained ranged between 6.07×10−3 to 12.03×10−3. The compositional results revealed the presence of the Sn, Co, O2 and some traces of other elements. The SEM images obtained show uniform surface without any voids or flaws. The micrographs show that the surfaces are composed of particles of slightly different sizes.

Aramid nanofiber-reinforced three-dimensional graphene hydrogels for supercapacitor electrodes

HypothesisSelf-assembled graphene hydrogels are notable in the field of electrochemical energy storage for their unique combination of excellent specific surface area, high porosity, and electrically conductive continuous network. However, graphene hydrogels suffer from poor mechanical integrity compared to layered architectures like graphene buckypapers, limiting their applications in practical devices. We propose the use of high strength, Kevlar®-derived polymeric nanofillers, aramid nanofibers (ANFs) as structural fillers to enhance graphene hydrogel’s shear modulus in the context of multifunctional (mechanical and electrochemical) architectures. ExperimentsGraphene hydrogels are fabricated using sol-gel self-assembly of graphene oxide (GO) nanosheets in presence of ammonium hydroxide. Colloidal dispersion of ANFs and GO are integrated using a novel combination of solvent exchange and dialysis approach to fabricate GO-ANF hydrogels with 0–15 wt.% of ANFs loading (dry weight basis). Shear modulus and electrochemical properties of resulting hydrogel composites are evaluated using rheology and symmetric supercapacitor cell. FindingsThe addition of 2 wt.% ANFs resulted in an 80% improvement in shear modulus compared to neat graphene hydrogel. Addition of ANFs resulted in gradual reduction of specific capacitance, with the specific capacitance of 190 F/g for neat graphene hydrogel, reducing to 128 F/g for an ANF loading of 15 wt.% (dry weight basis). This work shows the broader concept that adding high-strength nanofibers to a nanomaterial gel can add reinforcement provided that the gelation process itself is not disrupted.

Iron oxide impregnated mesoporous MCM-41: synthesis, characterization and adsorption studies

Mesoporous MCM-41 and MCM-41 impregnated with structural iron (Fe–MCM-41) were prepared by a facile surfactant based wet chemical method using tetraethyl orthosilicate, cetyl trimethyl ammonium bromide in the presence of ammonium hydroxide and FeSO4·7H2O as impregnated reagent. The prepared mesoporous materials were characterized by small and wide angle X-ray diffraction (XRD), XPS, FESEM, HRTEM, FTIR and N2 gas adsorption/desorption isotherm techniques. The results indicate the formation of high surface area (1266 m2/g) porous structure with particle size in the range of 200–400 nm for MCM-41. In case of Fe–MCM-41 the surface area decreases (880 m2/g) substantially with formation of iron oxide nanoparticles in the frame work of MCM-41. The obtained mesoporous materials were used as adsorbents for the removal of methylene blue from aqueous media. The percentage removal of the dye was found to be 99.9% for Fe–MCM-41 and 94.5% for MCM-41, respectively, by using 20 mL of dye solution with initial concentration of 100 mg/L and 0.05 g of each adsorbent. The maximum adsorption capacity of Fe–MCM-41 was found to be 194 mg/g and for MCM-41, it was 149.5 mg/g. This result suggests that the prepared Fe–MCM-41 is an effective adsorbent for decontamination of Methylene blue from aqueous media.

Purification of transferrin by magnetic nanoparticles and conjugation with cysteine capped gold nanoparticles for targeting diagnostic probes

Transferrin is an iron binding glycoprotein actively involved in the growth and maintenance of cell cycle. The transferrin receptors expression is increased on growing cancer/tumor cells for absorption of iron through transferrin and participation in biological activity. In this study, a novel method for the purification of transferrin by using magnetic nanoparticles (MNP) is developed and compared with reported method. Magnetic nanoparticles were synthesized by co-precipitation method under hydrothermal conditions in the presence of ammonium hydroxide. MNP were characterized by FTIR, VSM, DLS, TEM, and SEM. Purified transferrin was characterized by SDS-PAGE, MALDI-TOF, ELISA, Western blot, and its activity was further confirmed by iron binding assay and receptor binding assays. Purified transferrin was also conjugated with cysteine capped gold nanoparticles (GNP) and characterized by UV-Vis spectra, TEM, DLS, and fluorescent spectrophotometry. Transferrin conjugated cysteine capped GNP used as a targeted fluorescent probe on gastric cancer, tumor tissue and MDA-MB 231 cancer cells to confirm transferrin receptor binding activity and application as diagnostic probe. The purified transferrin showed stability and activity up to 36 months. The results indicated that the synthesized superamagnetic MNP are good for the purification of transferrin. A good yield of transferrin was purified by this method, good quality and showed active biological activity. GNP conjugated transferrin has a potential to be used in cancer diagnosis as targeted diagnosis probe in vivo and in vitro. Experiments are underway for utilizing transferrin as carrier for targeting drug delivery.

Towards encapsulation of thiol-ene mixtures: Synthesis of thioacetate cross-linker for in-situ deprotection

One drawback of thiol-ene mixtures is their poor shelf-life (due to a lack of stability) which limits their use in certain applications for which the compounds have to retain their activity (i.e. unreacted) for long time periods. To address this issue, the present work reports on the synthesis of a cross-linker containing a thiol group in a protected form (i.e. thioacetate). The conversion of the thioacetate groups into the corresponding thiol moieties after alkaline treatment was monitored by 1H NMR spectroscopy. The results showed that the thioacetate groups could be deprotected within 300 min using sodium hydroxide or ammonium hydroxide. Subsequently, the synthesized thioacetate cross-linker was combined with an acrylate-based compound to form a cross-linked network in a one-pot process via sequential deprotection into a thiol and subsequent thiol-ene Michael-type addition. In-situ gel formation in a one pot-process was only achieved in the presence of ammonium hydroxide as sodium hydroxide causes hydrolysis of the cross-linkable acrylate moieties.

Facile synthesis of defect-rich nitrogen and sulfur Co-doped graphene quantum dots as metal-free electrocatalyst for the oxygen reduction reaction

Carbon-based metal-free nanomaterials have attracted immense and persistent attention as electrocatalysts for oxygen reduction reaction (ORR) in fuel cells, due to their high electrocatalytic activity, long-term stability and low cost. Here, a facile hydrothermal treatment in the presence of ammonium hydroxide (NH4OH) and sodium sulfide (Na2S), as precursors, has been developed to synthesize heteroatom-doped graphene quantum dots (GQDs). For comparison, undoped graphene quantum dots (GQDs), nitrogen doped graphene quantum dots (N-GQDs), sulfur doped graphene quantum dots (S-GQDs) and nitrogen and sulfur co-doped graphene quantum dots (N,S-GQDs) have been synthesized with the same method. The as-obtained N,S-GQDs possess a high N-doping content up to 9.36% and low S-doping content up to 0.78%, with a uniform size distribution similar to that of GQDs, N-GQDs and S-GQDs. Interestingly, the multi-types of NC or CSC bonding in metal free N,S-GQDs can significantly enhance the electrocatalytic activity for the oxygen reduction reaction (ORR), with the electron transfer number as good as 3.82, which verify the importance of our facile synthesis method to fabricate metal-free electrocatalysts for ORR and other electrochemical applications.

On Possible Changes in the Physical Characteristics of the Aerosol in the Deep Layers of the Atmosphere of Saturn

This study is dedicated to determining the values of the physical parameters of cloud particles in the deep layers of Saturn’s atmosphere using the data from remote measurements of the solar radiation field diffusely reflected by the giant planet. In the previous studies, using the effective optical depth method, from the spectral measurements of the geometric albedo of Saturn in 1993 in the wavelength range of 300–1000 nm, a pressure dependence of the aerosol scattering component of the optical depth, i.e., a change in its value with altitude in the atmosphere, was obtained. The analysis of the initial data was performed in the long-wave part of the spectrum in the methane absorption lines of different levels of absorption with the centers at wavelengths of λ = 619, 727, 842, 864, and 887 nm. At certain altitude levels in the deep layers of the atmosphere of the giant planet, the indicated dependence shows the features that possibly reflect changes in the physical characteristics of aerosol. Therefore, the aim of this work was to determine the possible values of the physical parameters of aerosol particles in the deep layers of Saturn’s atmosphere at altitudinal levels with the features noted above. As a result, an increase in the effective radius of cloud particles was observed in the transition from the outer to the deeper layers of the atmosphere: from 1.4 μm in the upper part of atmosphere to 1.83 μm in the altitudinal region with a pressure of 1.0–1.25 bar and up to 2.2–2.4 μm in the region with a pressure of 1.5–2.0 bar. In the latter segment, a decrease by 3.5% was revealed in the real part of the refractive index of aerosol particles. A possible reason for this decrease is the change in the phase state of aerosol particles in the lower and warmer atmospheric layers of Saturn due to the presence of ammonium hydroxide in their composition at a sufficient high concentration.

Efficient Gelation of Graphene Oxide Aqueous Dispersion Induced by Sonication‐Promoted Leuckart Reaction

AbstractGraphene oxide (GO) undergoes a rapid gelation process in the presence of ammonium hydroxide and formic acid at room temperature which is promoted by ultrasonication. Infrared and X‐ray photoelectron spectroscopy proved partial reduction of GO and nitrogen incorporation, resulting from sonication‐promoted Leuckart reactions at GO carbonyl groups. The amine groups produced via Leuckart reactions undergo further reactions that result in salt bridges with carboxylic groups and covalent cross‐links, both of which contribute to the stabilization of the resulting hydrogel. The resultant GO hydrogel exhibits enhanced thermal stability.

Scalable synthesis of high purities ammonium dinitramide and its decomposition characteristics

Scalable synthesis of high purities ammonium dinitramide (ADN), 98.2% or more has been performed through conversion of potassium dinitramide (KDN) into ammonium dinitramide using guanylurea dinitramide (GUDN) as a precursor, which can be scalable up to a few hundred grams. The obtained ADN and corresponding liquid ADN blended with fuel was subject to the decomposition reaction with and without iridium catalyst. The result of the decomposition reaction suggested that the blending of methanol with ADN gave a high performance. It has been shown that the presence of ammonium hydroxide in the blend maintained pH around 10 and also stabilized the ADN solution for more than 20day at 60°C.

Influence of Zeolitic imidazolate framework-8 on the thermal stabilization of poly(vinyl chloride)

A zeolitic imidazolate framework material (ZIF-8) was prepared from stoichiometric zinc nitrate and 2-methylimidazole at room temperature in the presence of ammonium hydroxide. The material was characterized by a series of methods and used as a thermal stabilizer for poly (vinyl chloride) (PVC) film. The properties of the stabilized PVC were investigated using Congo red test, thermal aging test and thermal gravimetric analysis (TGA). Compared with the stabilizing efficiencies of some commonly-used reference stabilizers (e.g. CaSt2 and ZnSt2), the stabilizers including ZIF-8 [such as CaSt2/ZnSt2/ZIF-8 and ZnSt2/ZIF-8] exhibit better initial color stability and long-term thermal stability for PVC. The static thermal stability time was significantly prolonged from 33.13 min for PVC/CaSt2/ZnSt2 to about 128.92 min for PVC/ZIF-8/ZnSt2 at 180 °C. The superior performance is attributed to the synergistic effect of ZIF-8 and ZnSt2. The imidazole ligand of ZIF-8 can strongly absorb hydrogen chloride and form complexes with ZnCl2 generated from ZnSt2 in the PVC degradation process. In addition, the double bonds of ZIF-8 may help to form stable compounds with polyenes to further retard the PVC degradation. Dynamic mechanical and tensile properties of the PVC films were also studied.

Determination of Diquat Residues in Potato Using Reversed-Phase Liquid Chromatography with Tandem Mass Spectrometry.

A simple, modified quick, easy, cheap, effective, rugged, and safe procedure was developed for the determination of diquat in potato using reversed-phase LC coupled with tandem MS (MS/MS) in a total run time of 10 min. Different sample preparation parameters (pH modifier type, sample size, and elevated temperature) were tested and optimized. Potato sample was extracted with acetonitrile in the presence of ammonium hydroxide at 80°C. Phase separation was obtained by shaking the extract with magnesium sulfate and sodium chloride, and analysis was done using LC-MS/MS. Matrix-matched standard calculations were used to compensate for matrix-induced suppression in LC-MS/MS determination. The precision and trueness of the method were determined from recovery experiments on five replicates of spiked blank potato samples at 0.01, 0.05, and 0.1 mg/kg. The range of the obtained recoveries was 74-110%, with RSD values <5% for all the concentrations.