Concentration Of Diphenylamine Research Articles

Understanding the biological impact of organic pollutants absorbed by nanoplastics

Many organisms are consuming food contaminated with micro- and nanoparticles of plastics, some of which absorb persistent organic pollutants (POPs) from the environment and acting as carrier vectors for increasing the bioavailability in living organisms. We recently reported that polymethylmethacrylate (PMMA) nanoparticles at low concentrations are not toxic to animal models tested. In this study, the toxicity of diphenylamine (DPA) incorporated PMMA nanoparticles are assessed using barnacle larvae as a model organism. The absorption capacity of DPA from water for commercially available virgin PMMA microparticles is relatively low (0.14 wt%) during a 48 h period, which did not induce exposure toxicity to barnacle nauplii. Thus, PMMA nanoparticles encapsulated with high concentrations of DPA (DPA-enc-PMMA) were prepared through a reported precipitation method to achieve 40% loading of DPA inside the particles. Toxicity of DPA-enc-PMMA nanoparticles were tested using freshly spawned acorn barnacle nauplii. The observed mortality of nauplii from DPA-enc-PMMA exposure was compared to the values obtained from pure DPA exposure in water. The mortality among the exposed acorn barnacle nauplii did not exceed 50% even at a high concentration of DPA inside the PMMA nanoparticles. The results suggest that the slow release of pollutants from polymer nanoparticles may not induce significant toxicity to the organism living in a dynamic environment. The impact of long-term exposure of DPA absorbed plastic nanoparticles need to be investigated in the future.

Electrochemical detection of toxic anti-scald agent diphenylamine using oxidized carbon nanofiber encapsulated titanium carbide electrocatalyst.

Two dimensional (2D) titanium carbide (Ti-C) is an analogues of graphene have tremendous attention in recent years due to their high electrical conductivity and catalytic activity. Herein, we have synthesized Ti-C micro particles based on the template-assisted method and subsequently integrated with oxidized carbon nanofiber (f-CNF) through ultrasonication technique. The prepared Ti-C/f-CNF composite was subjected to various structural and morphological characterization techniques including the X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS). The all followed studies confirmed the formation and crystalline nature of prepared Ti-C/f-CNF nanocomposite. Further, the proposed Ti-C/f-CNF composite modified electrode was successfully applied as an electrocatalyst for the electrochemical detection of diphenylamine (DPA) in food. DPA is known as an anti-scald agent used to post harvest treatment of fruits. However, the higher concentration of DPA causes some hazardous side effects to human. Thus, the detection of DPA is an important concern in healthcare research. Eventually, the proposed Ti-C/f-CNF/SPCE exhibited ultra-low detection limit of (0.003 μM) with a linear range of 0.04-56.82 μM towards the detection of DPA. Moreover, the practicability of the proposed sensor was tested by real sample analysis by using fresh apple extract. Remarkably, the proposed sensor showed an excellent recovery range from 106.8% to 108% for the detection of DPA in spiked apple extract. Finally, we concluded that the integration of f-CNF with Ti-C is significantly enhanced both electrical conductivity and electrocatalytic activity for sensor application.

Least Absolute Shrinkage and Selection Operator as a Multivariate Calibration Tool for Simultaneous Determination of Diphenylamine and its Nitro Derivatives in Propellants

AbstractDetermination of diphenylamine (DPA) and its nitro derivatives received great attention for storing, deposition and on‐time usage of propellants. Herein, we present a novel and simple method for simultaneous determination of DPA and its nitro derivatives in solid propellants using UV‐Vis spectroscopy and chemometrics techniques. The UV‐Vis spectra of the analytes revealed strong overlap and it was difficult to determine them individually in their mixture without any separation and purification. To tackle the overlapping problem in collected spectra, analysis of first‐order UV‐Vis data was performed using multivariate calibration techniques. In this way, principle component regression (PCR), different modes of partial least square (PLS) and least absolute shrinkage and selection operator (LASSO) have been used for correlating the collected spectra to the concentration of DPAs in synthetic and real samples. The important variables were selected by confining the L1‐norm of the regression coefficients in multivariate model via the shrinkage and selection operator in LASSO approach. The results obtained by LASSO regression technique in this work were superior to those obtained by different modes of PLS algorithm. Moreover, it is shown that LASSO can be used as a reliable variable selection and modeling technique in multivariate calibration studies. Generally, the proposed strategy in this work is simple, non‐destructive, low‐cost and rapid and can be effectively applied for simultaneous determination of DPA and its nitro derivatives in solid propellants.

Light-harvesting complexes from purple sulfur bacteria Allochromatium minutissimum assembled without carotenoids

Effect of carotenoid (Car) biosynthesis inhibitor diphenylamine (DPA) on purple sulfur bacteria Allochromatium (Alc) minutissimum cell growth has been investigated. Cell growth in the presence of maximum concentration of DPA results in practically complete suppression (∼99%) of carotenoids (Cars) according to the spectrophotometric, HPLC and CD data. Phytoene does not replace the colored carotenoids in these cells. Also Phytoene does not accumulate in large amounts in the cells treated with DPA. A new method for calculating the content of Cars in the complexes from the cells with inhibited Car synthesis including the number of empty Car’s “pockets” has been used. Our results together with published data devoted to DPA action on the cell growth of purple bacteria revealed that Phytoene was not accumulated in the cells treated with DPA. We have concluded that (i) DPA completely inhibits or strongly reduces synthesis of the colored Cars in the cells of purple bacteria, (ii) Phytoene is the main one among the trace amounts of the other Cars in the case of significant inhibition of Car biosynthesis (80–90% or higher).The amount of the LH2 complexes presented in the membranes of Alc minutissimum was found to be little dependent on DPA. From DPA-grown cultures it was possible to isolate Car-less both the LH1 (as LH1–RC complex) and the LH2 complexes. Electronic absorption properties of BChl’s were very similar to those isolated from the control cells. It is shown by HPLC data that the 100 LH2 complexes from cells of Alc minutissimum, in which the synthesis of Car was depressed, contained ∼9 Car molecules and 5 Phytoene molecules. Thus, only nine (with 1 Car molecule per a complex) or less (if more than one Car molecule per a complex) of the 100 LH2 complexes contain molecules of Cars. It means that 90 or more LH2 complexes from each 100 ones are assembled without any Cars. This is in strong contrast with the previous results obtained with purple non-sulfur bacterium Rhodobacter sphaeroides, where the amount of LH2 presented in the membrane was directly correlated to the amount of the carotenoids synthesized (H.P. Lang, C.N. Hunter, The relationship between carotenoid biosynthesis and the assembly of the light harvesting LH2 complex in Rhodobacter sphaeroides, Biochem. J. 298 (1994) 197–205). Our results show that although the presence of Car molecules is important for the stability of the LH2 complexes the overall native structure can be maintained without any Cars at least in the case of purple sulfur bacteria.

Semiquantitative determination of some nitrogen compounds by the formation of charge-transfer complexes of diphenylamine with p-dimethylaminobenzaldehyde by capillary solid-state spot-tests

The interactions of p-dimethylaminobenzaldehyde ( p-DAB) and potassium hydrogen sulphate (PHS) in equimolar ratio with various concentration of diphenylamine (solid test material) have been investigated by capillary spot-tests technique in order to investigate the effect of temperature and volume of material in test-tube. The formation of the colored boundary in the capillary is taken for the detection of organic compounds by spot-tests at different temperature and volume of solid test material.

Deposition, growth processes and characterization of poly(diphenylamine-co-N-methyl aniline)

Copolymerization of diphenylamine (DPA) with N -methyl aniline (NMA) was carried out in aqueous sulfuric acid medium by pulse potentiostatic method (PPSM). The copolymer film was grown on the surface of the working (platinum) electrode for various experimental conditions and the charge associated with film deposition was followed by cyclic voltammetry. The charge values were correlated to the amount of copolymer deposition (growth) and amount of copolymer deposited per unit time of electropolymerization (growth rate). The kinetics of the electrochemical copolymerization was followed by deducing the growth and growth rate equations in terms of charge associated with the film deposition and the conditions of electropolymerization. The deduced growth and growth rate functions indicate the dependences of concentration of DPA and NMA. The copolymer was also synthesized through oxidative polymerization and characterized by conductivity measurement, Fourier transform infra-red spectroscopy, nuclear magnetic resonance spectroscopy, ultra violet–visible spectroscopic techniques and thermogravimetric analysis.

Deposition, growth processes and characterization of poly(diphenylamine-co- N-methyl aniline)

Copolymerization of diphenylamine (DPA) with N-methyl aniline (NMA) was carried out in aqueous sulfuric acid medium by pulse potentiostatic method (PPSM). The copolymer film was grown on the surface of the working (platinum) electrode for various experimental conditions and the charge associated with film deposition was followed by cyclic voltammetry. The charge values were correlated to the amount of copolymer deposition (growth) and amount of copolymer deposited per unit time of electropolymerization (growth rate). The kinetics of the electrochemical copolymerization was followed by deducing the growth and growth rate equations in terms of charge associated with the film deposition and the conditions of electropolymerization. The deduced growth and growth rate functions indicate the dependences of concentration of DPA and NMA. The copolymer was also synthesized through oxidative polymerization and characterized by conductivity measurement, Fourier transform infra-red spectroscopy, nuclear magnetic resonance spectroscopy, ultra violet–visible spectroscopic techniques and thermogravimetric analysis.

Forecasting Scald Potential of Delicious Apples in New England

Susceptibility to superficial scald on apples varies with season, orchard location, and time of harvest, and is related to seasonal weather variation. If scald potential could be forecast at the time of harvest, then appropriate antiscald treatment decisions could be made. This could result in 1) reduced use of scald inhibiting diphenylamine (DPA) dips, with their accompanying fungicides and 2) reduced loss of stored fruit due to scald. Analyses of scald-related data collected at the UMass Horticultural Research Center (HRC) from 1986 to 1993 have resulted in development of equations relating scald development to harvest date, number of preharvest days in which the temperature fell below 10 °C, and harvest starch score. Equations to identify lots of fruit which were particularly scald susceptible or particularly scald resistant were also developed. These equations were tested in 1995 and 1996 on 'Delicious' apples harvested from orchards throughout New England and stored at the HRC. About 80% of the 182 lots of fruit were placed in the correct susceptibility category. DPA treatments were applied to the Massachusetts fruit in both years, and forecasts were almost 100% effective for determining the appropriate concentration of DPA needed to control scald. Effects of controlled atmosphere (CA) storage on scald development, scald forecasting, and necessary scald control measures will vary according to the atmosphere, but initial data show forecasting trends to be about the same for CA as for air-stored fruit.

Inhibition of the thin-film oxidation of n-dodecane by diphenylamine

The inhibition by diphenylamine (DPA) of the oxidation of a thin film of n-dodecane has been studied over the temperature range 180–230 °C by following the consumption of gaseous oxygen, the disappearance of the inhibitor and the formation of peroxides. At the start of the reaction there is an induction period which increases linearly with the initial concentration of inhibitor. During the first part of this induction period there is apparently no change in the concentration of DPA, but it has all been consumed by its end, although there is only a negligible decrease in the absorption at 1600 and 3400 cm–1 due to N—H. Thus it is concluded that abstraction of the amino hydrogen cannot be involved in the inhibition mechanism under the present experimental conditions, and it is suggested that the first step is probably an electron-transfer reaction between an alkyl radical and the inhibitor.

Changes in the polysaccharide biosynthesis of Candida guilliermondii induced by diphenylamine

Diphenylamine (DPA) inhibits the formation of glucan in Candida guilliermondii while stimulating that of mannan. The total polysaccharide of cells decreases when growing in the presence of DPA. These effects are dependent on the concentration of DPA. Compared with 14 structure-like substances, DPA was found to have the strongest activity.

Superficial scald, a functional disorder of stored apples. 3. Concentration of diphenylamine in the fruit after treatment.

AbstractAfter treatment of apples with diphenylamine most of it was found in the peelings (1 mm thick) and was distributed approximately as follows: 60 % in the cuticle, 20 % in the epidermis, and 20 % in the hypodermis and cortex (assumed to be predominantly in the hypodermis). Treated apples lost 95 % or more of the original diphenylamine during 30 weeks' storage at 1°. A concentration in the peelings of about 0.2 μg/cm2 appeared to be the minimum required to inhibit scald‐inducing reactions.Concentrations of diphenylamine immediately after treatment and the minimum effective concentrations were estimated in the cuticle, epidermis, and hypodermis. It appeared that the concentration needed to inhibit the scald‐inducing reactions was appreciably less than that required for inhibiting respiration, phosphorylation, or the oxidation of carotene.

Diphenylamine inhibition of electron transport in plant mitochondria

Diphenylamine (DPA) at concentrations of 10 −4 M and above inhibits NADH oxidase and succinoxidase activities of plant mitochondria. At the lower concentrations (≦2.7 × 10 −4 M) the inhibitory effects result primarily from DPA acting in the region between succinic and NADH dehydrogenases, and the first cytochrome component of the electron transport chain(s). This conclusion was based on the following results: (1) DPA delayed the reduction of mitochondrial cytochromes in the sweet potato succinoxidase system; no reduced-oxidized cytochrome pairs were observed; (2) NADH- and succinic-cytochrome c reductase activities of the mitochondria were severely inhibited by 2.7 × 10 −4 M DPA; (3) succinic dehydrogenase and NADH diaphorase activities of the mitochondria were not inhibited by that concentration of DPA; (4) menadione effects an antimycin A-insensitive shunt from NADH to cytochrome c which is not inhibited by DPA; and (5) much smaller effects were exerted by DPA on mitochondrial cytochrome c oxidase activity. The antimycin A-insensitive respiration in sweet potato mitochondria was also inhibited by DPA, suggesting that DPA may be useful in testing alternate pathway theories.

Control of superficial scald on Granny Smith apples with diphenylamine

The preliminary work of Smock (1955) indicated that treatment of apples with diphenylamine (DPA) offered a promising new method of controlling superficial scald on cool-stored apples. The effect of DPA and various methods of application hare been widely studied under Australian conditions over five seasons, Granny Smith apples grom-n in New South Wales being used. Treatment of fruit with a suitable concentration of DPA prevented the development of scald on fruit cool-stored in air, in controlled atmospheres, and in polyethylene film box liners, even when scald was severe and not controlled by oiled wraps. DPA was successfully applied to the fruit by impregnating it into standard paper wraps, by post-harvest dipping, and by pre-harvest spraying. It was found that there was a quantitative relation between the severity of scald and the concentration of DPA required to control it. DPA was shown to have a very limited mobility in the fruit. Residues in the fruit were related to both the amount applied and the method of application, and in all cases were low after cool storage. DPA appears to have a sufficiently low phytotoxicity for use as a pre-harvest spray. Its human toxicity is still under investigation. If approved for use on apples it will probably be in a purified form.

THE REACTION BETWEEN DIPHENYLAMINE AND NITRATES IN ULTRAVIOLET LIGHT

Under the activating influence of short-wave ultraviolet light, diphenylamine and nitrate ions in solution or on filter paper react to yield a yellow-colored product. Between pH 4 and 10 this consists mainly of 2-nitrodiphenylamine and 4-nitrodiphenylamine. Over this range of pH, the absorption maxima at 405 mμ did not shift; however, the intensity of absorption appeared to reach a minimum at or near neutrality and then increase rapidly as the solution was made more alkaline. The reaction rate was not affected by lowering the concentration of diphenylamine from 0.38% to 0.038%. A similar change in nitrate concentration decreased the rate 5.4 times. No evidence of nitroso compounds was found. Possible mechanisms are suggested.