N,N-Diethyl-p-phenylenediamine (DPD)

In this study, a novel assay for the detection of free chlorine is proposed for the first time. It is based on a redox reaction that occurs between triangular silver nanoprisms and free chlorine, which results in a morphological transformation and a change of the localized surface plasmon resonance (SPR) of the triangular silver nanoprisms. In the assay, the presence of free chlorine would etch triangular silver nanoprisms from triangle to round, leading to a significant blue-shift SPR absorption band of triangular silver nanoprisms...

With the maturation and certification of several ballast water management systems that employ chlorine as biocide to prevent the spread of invasive species, there is a clear need for accurate and reliable total residual oxidants (TRO) technology to monitor treatment dose and assure the environmental safety of treated water discharged from ships. In this study, instruments used to measure TRO in wastewater and drinking water applications were evaluated for their performance in scenarios mimicking a ballast water treatment application (e...

Promising developments in application of carbon nanotubes (CNTs) have raised concern regarding potential biological and environmental effects upon their inevitable release to the environment. Although some CNTs have been reported to generate reactive oxygen species (ROS) under light, limited information exists on ROS generation by these materials in the dark. In this study, generation of ROS was examined, initiated by electron transfer from biological electron donors through carboxylated single-walled carbon nanotubes (C-SWCNT) to molecular oxygen in water in the dark...

Free chlorine is extensively used for water and wastewater disinfection nowadays. However, it still remains a big challenge to determine the rate constants of rapid chlorination reactions although competition kinetics and stopped-flow spectrophotometric (SFS) methods have been employed individually to investigate fast reaction kinetics. In this work, we proposed an SFS competition kinetics method to determine the rapid chlorination rate constants by using a common colorimetric reagent, N,N-diethyl-p-phenylenediamine (DPD), as a reference probe...

In this study, a micro-flow-batch analyzer (μFBA) with solenoid micro-pumps for the photometric determination of iodate in table salt is described. The method is based on the reaction of iodate with iodide to form molecular iodine followed by the reaction with N,N-diethyl-p-phenylenediamine (DPD). The analytical signal was measured at 520 nm using a green LED integrated into the μFBA built in the urethane-acrylate resin. The analytical curve for iodate was linear in the range of 0.01-10.0 mg L(-1) with a correlation coefficient of 0...

Free chlorine was found to be able to destroy the passivated surface of the graphene quantum dots (GQDs) obtained by pyrolyzing citric acid, resulting in significant quenching of their fluorescence (FL) signal. After optimizing some experimental conditions (including response time, concentration of GQDs, and pH value of solution), a green and facile sensing system has been developed for the detection of free residual chlorine in water based on FL quenching of GQDs. The sensing system exhibits many advantages, such as short response time, excellent selectivity, wide linear response range, and high sensitivity...

UNLABELLED: Trichloramine (NCl(3)) is recognized as an irritant of the human respiratory system and other tissues. Processes that lead to volatilization from the liquid phase allow for human exposure to gas-phase NCl(3) in swimming pool settings. The dynamics of these processes are not well defined. A N,N-diethyl-p-phenylenediamine/potassium iodide (DPD/KI)-based wet-chemistry method for measuring gas-phase NCl(3) concentration was verified and applied in chlorinated, indoor swimming pool facilities...

The influence of dissolved organic matter (DOM), such as humic acid (HA) and hydroxybenzoic acids, on the determination of H(2)O(2) via a colorimetric method using N,N-diethyl-p-phenylenediamine (DPD) was examined. The influence of DOM on absorbance decay at 551 nm, which represents the wavelength for maximum absorption of the oxidized species of DPD (DPD(+)), were investigated in detail. Significant decrease in the absorbance at 551 nm was observed in the presence of HA and gallic acid. This resulted in a fadeout of the purple color of DPD(+), which, in term, created great difficulties in the measurement of H(2)O(2) in solutions which contain DOM...

The suitability of application of a number of previously used methods for the evaluation of the oxidizing equivalent (OE) of manganese in natural waters is compared with a new method, which depends upon colour development of the dye N,N'-diethyl-p-phenylenediamine (DPD) upon oxidation by oxidized forms of manganese. The effect of introducing a commonly used metabolic poison, azide, into the most reliable of these determinations of OE has also been assessed.

In the determination of free and combined chlorine, the reaction of permanganate standards with N,N-diethyl-p-phenylenediamine (DPD) exhibits nonlinearity presumably because both the colored semiquinoid product and the colorless quinoid product are both formed. The titrimetric DPD method titrates both of the products while the colorimetric method monitors only the colored semiquinoid products. This results in a nonlinear response for the colorimetric method above 1.0 mg/l. as Cl(2). Under FIA conditions, the nonlinearity of the DPD colorimetric method is eliminated in the 0...

In this study, a sensitive and rapid method for hydrogen peroxide (H(2)O(2)) determination has been developed with the aid of oxidation decolorization of methyl orange (MO) by using Fenton reactions, because the decolorization extent of MO solution (at the maximum absorption wavelength of 507 nm) is proportion to the concentration of H(2)O(2). Under optimum conditions, this spectrophotometric method for the H(2)O(2) analysis yields a dynamic range of H(2)O(2) concentration from 5.0 x 10(-7) to 1.0 x 10(-4) mol L(-1) (r=0...

A highly sensitive, simple and selective kinetic method was developed for the determination of ultra-trace levels of formaldehyde and acetaldehyde based on their catalytic effect on the oxidation of N,N-diethyl-p-phenylenediamine (DPD) with hydrogen peroxide. The reaction was monitored spectrophotometrically by tracing the formation of the red-colored oxidized product of DPD at 510nm, within 30s of mixing the reagents. The optimum reaction conditions were: 20mmolL(-1) DPD, 250mmolL(-1) H(2)O(2), 150mmolL(-1) phosphate, 150mmolL(-1) citrate and pH 6...

In this work an automatic photometric procedure for the determination of chlorine in bleach samples employing N,N'-diethyl-p-phenylenediamine (DPD) as chromogenic reagent is described. The procedure was based on a falling drop system where the analyte (Cl(2)) was collected by a DPD solution drop (50 microL) after its delivery from the sample bulk that was previously acidified. The flow system was designed based on the multicommutation process assembling a set of three-way solenoid valves, which under microcomputer control afforded facilities to handle sample and reagent solution in order to control analyte delivering and solution drop generation...

Three methods for the determination of chloramines in water were compared using pH-buffered nanopure water and natural organic matter (NOM) solutions. We investigated whether the N,N-diethyl-p-phenylenediamine (DPD) colorimetric method and/or an adapted indophenol method (Hach MonochlorF) are suitable for determining the concentration of monochloramine in drinking water. Membrane introduction mass spectrometry (MIMS) was used as a reference analysis method to determine the different chloramine species in water...

A signals ratio method combined with wavelet transform was proposed for the resolution of a weak voltammetric signal overlapped by other components. The signals ratio method usually suffers from interference from noise and baseline contained in the original signals because these factors cause distortion of the signals ratio. The multiresolution capability of the wavelet transform method was exploited here to simultaneously remove or reduce the noise and background. As a result, a deformation-free signals ratio with good signal-to-noise ratio (SNR) was obtained even for very noisy signals...

The present study was aimed at developing a portable miniaturized FIA system with a two-electrode based amperometric detector for on-site monitoring of residual chlorine in environmental samples. The electrode potential control and current data collection were conducted with a home-designed potentiostat with a size of 150 x 100 x 40 mm and the weight of 350 g. It was confirmed that the amperometric response increased in proportion to the chlorine concentration up to 5 microg/ml, and the detection limit for chlorine was 0...

The antioxidant effects of ceruloplasmin (CAS 9031-37-2) against oxygen free radicals (.O2-, .OH, 1O2) and their by-products (H2O2, HOCl), generated by electrolysis of Krebs-Henseleit buffer, were determined in vitro by the DPD (N,N-diethyl-p-phenylenediamine) colorimetric method and ex vivo by quantifying cardiodynamic variables of the isolated perfused rat heart. Purified ceruloplasmin (1 mumol/l) displayed a high antioxidant capacity in vitro (89.2%), while the scavenging capacity of superoxide dismutase (SOD) in equimolar concentrations was 38...