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

Hydrogen peroxide (H2 O2 ), peroxymonosulfate (PMS), and peroxydisulfate (PDS) are key bulk oxidants in many advanced oxidation processes (AOPs) for treating chemically contaminated water. In some systems these peroxides may coexist in solution either through intentional co-addition or their inadvertent formation (especially H2 O2 ) due to reaction chemistry. While many analytical methods to determine these peroxides individually have been established, mutual interference among the peroxides in such methods has seldom been evaluated, and new methods or variants of established methods to selectively determine peroxides in binary mixtures are lacking...

Sodium percarbonate (SPC) concentration can be determined spectrophotometrically by using N, N-diethyl-p-phenylenediamine (DPD) as an indicator for the first time. The ultraviolet-visible spectrophotometry absorbance of DPD•+ measured at 551 nm was used to indicate SPC concentration. The method had good linearity (R2 = 0.9995) under the optimized experimental conditions (pH value = 3.50, DPD = 4 mM, Fe2+ = 0.5 mM, and t = 4 min) when the concentration of SPC was in the range of 0-50 μM. The blank spiked recovery of SPC was 95-105%...

With the spread of coronavirus infections, the demand for disinfectants, such as a sodium chlorite solution, has increased worldwide. Sodium chlorite solution is a food additive and is used in a wide range of applications. There is evidence that chlorous acid or sodium chlorite is effective against various bacteria, but the actual mechanism is not well understood. One reason for this is that the composition of chlorine-based compounds contained in sodium chlorite solutions has not been clearly elucidated. The composition can vary greatly with pH...

The residual free chlorine concentration is an important parameter to evaluate the potability of water and the efficiency of disinfection in the water treatment system. As a restricted range of residual free chlorine concentration at all points of the distribution network is needed to ensure efficiency and to avoid deleterious effects, fast and in situ quantification of this specie is important. This work deals with the development and validation of two procedures based on DPD (N,N-diethyl-p-phenylenediamine) and OT (ortho-tolidine, 3,3-dimethylbenzidine) for the determination of residual free chlorine in water by exploiting a flow-based microdevice built with Low Temperature Co-Fired Ceramic (LTCC) technology...

In this article, a novel metal-organic framework, namely MIL-101(FeII ), was firstly synthesized via a facile method. In the presence of H2 O2 , MIL-101(FeII ) possesses excellent peroxidase-like activity toward the classical chromogenic substrate, N,N-Diethyl-p-phenylenediamine sulfate salt (DPD). The substitution of Fe2+ enhances the construction of Fe(II)-oxo nodes and accelerates electrons transfer between DPD and H2 O2 , thereby improving the peroxidase-mimicking catalytic activity of MIL-101(FeII ) nanoenzyme...

A method for measuring peracetic acid vapors in air using impinger sampling and field-portable colorimetric analysis is presented. The capture efficiency of aqueous media in glass and plastic impingers was evaluated when used for peracetic acid vapor sampling. Measurement of peracetic acid was done using an N,N -diethyl-p-phenylenediamine colorimetric method with a field-portable spectrometer. The linearity of the N,N -diethyl-p-phenylenediamine method was determined for peracetic acid both in solution and captured from vapor phase using glass or plastic impingers...

A specific DMPO-OH adduct signal (1:2:2:1)related to hydroxyl radical generation in a longterm stored improved iodide formulation, tentatively designated as the distilled KMT reagent which prepared from a pH 0.3 solution containing FeCl3 , EDTA, KI and ethanol termed the KMT reagent, was detected by electron spin resonance (ESR) spectroscopy.Although the color intensities of N,N,N,N-tetramethyl-p-phenylenediamine (TMPD) and N,N-diethyl-p-phenylenediamine (DPD) differ, the mixture of the long-term stored distilled KMT reagent and TMPD exhibited a purple color similar to Wurster's blue, and the mixture of the long-term stored distilled KMT reagent and DPD exhibited a pink color similar to Wurster's red...

In this study, a BDD electrolytic oxidation-ceramic membrane ultrafiltration (EO-CM) system for the removals of antibiotics, organic matters and ammonia in wastewater was evaluated. Sulfamethazine (SMZ) was degraded following a pseudo first-order kinetics. The removal rate of SMZ improved with the increase of electro-oxidation time (0-60 min) and current density (5-30 mA/cm2 ). During the BDD electro-oxidation process, H2 O2 and hydroxyl radicals (•OH) were generated which were detected by N, N-diethyl-p-phenylenediamine (DPD) method and electron paramagnetic resonance spectroscopy (EPR), respectively...

A new spectrophotometric method for measuring permanganate index (chemical oxygen demand using potassium permanganate (KMnO4 ) as oxidant, CODMn ) in water was established. The method was based on the rapid oxidation of N,N-diethyl-p-phenylenediamine (DPD) by residual KMnO4 in digestion solution under neutral pH condition to form the stable pink radical (DPD●+ ). Only 20 s were enough to form the pink DPD●+ . The generated DPD●+ could be quantitatively measured by a visible spectrophotometer at 551 nm...

Free available chlorine (FAC) is the most widely used chemical for disinfection and in secondary disinfection; a minimum chlorine residual must be present in the distribution system. FAC can also be formed as an impurity in ClO2 production as well as a secondary oxidant in the ClO2 application, which has to be monitored. In this study, a new method is developed based on the reaction of FAC with glycine in which the amine group selectively scavenges FAC and the N-chloroglycine formed can be measured by ion chromatography with conductivity detector (IC-CD)...

Peracetic acid (PAA) water solutions is applied for disinfection of industry systems, food products and non-potable water. Commercially available peracetic acid is always supplied mixed with hydrogen peroxide (H2 O2 ). H2 O2 degrade slower than the peracetic acid which creates a need to quantify both peroxides separately to gauge the disinfection power of the solution and the residuals. Two combinations of colorimetric reactions are presented that allows simultaneous quantification at the mg·L-1 level used in disinfection liquids and water disinfection...

A microfluidic sensor was studied for the photometric detection of active chlorine, total chlorine, and pH in swimming pool samples. The sensor consisted of a four-layer borosilicate glass chip, containing a microchannel network and a 2.2 mm path length, 1.7 mL optical cell. The chip was optimised to measure the bleaching of methyl orange and spectral changes in phenol red for quantitative chlorine (active and total) and pH measurements that were suited to swimming pool monitoring. Reagent consumption (60 mL per measurement) was minimised to allow for maintenance-free operation over a nominal summer season (3 months) with minimal waste...

A low-cost and environmentally-friendly spectrophotometric method for hydrogen peroxide (H2 O2 ) determination based on the oxidative coloration reaction of N,N'-diethyl-p-phenylenediamine (DPD) via the Fenton reactions in aqueous water was established. The generated pink radical cation (DPD+ ) showed maximum absorption at 551 nm. Importantly, under the optimal conditions (pH 3.0, 20 mM DPD, 1.5 mM Fe(II) and reaction time of 45 s), the increase in absorbance at 551 nm for DPD+ generation was linear with respect to the addition of H2 O2 (0-12 μM)...

Copper coordinated with amino acid residues is essential for the function of many proteins. In addition, copper complexed to free l-Histidine, as [Cu(His)2 ], is used in the treatment of the neurodegenerative Menkes disease and of cardioencephalomyopathy. This study was aimed to coordinate copper(II) with four small ligands (l-Serine, l-Histidine, Urea and Biuret) and to evaluate structural features, stability, antioxidant activity and neuronal compatibility of the resulting complexes. All complexes were synthesized with CuCl2 and purified by precipitation in alcohol...

Chlorination is the most common method to control water qualities, in some case on-site outdoor measurements are required to measure easily-decaying residual chlorine concentration appropriately without delay. In this study sunlight-induced unexpected colour development (UCD) of N, N-diethyl-p-phenylenediamine (DPD) colorimetric measurement was studied under several sun exposure conditions. The colour development level was evaluated with reference to chlorine concentration (mg/L) and relationships between colour development rate (mg/L min) and intensities of solar were investigated...

A sensitive spectrophotometric method (the N,N-diethyl-p-phenylenediamine (DPD) method) was established for the determination of trace permanganate concentration (0-10 μM) in water. The DPD method was based on the oxidative coloration reaction where permanganate could oxidize DPD to form the red colored DPD radical (DPD•+ ) with a second-order rate constant of 2.96 × 104  M-1  s-1 at pH 6 (50 mM phosphate buffer). The generated DPD•+ could be quantitatively measured at 551 nm using an UV-Vis spectrophotometer...

In this work, a colorimetric methodology was developed for free chlorine determination by constructing a fiber-optic sensor (FOS) which was designed by using a small LED as light source and two silica fibers as light transmission elements. Then the FOS was integrated with the sequential injection lab-on-valve (SI-LOV) manifold to fabricate a FOS-SI-LOV system for free chlorine detection. The colorimetric determination was based on the reaction between N,N-diethyl-p-phenylenediamine (DPD) reagent and free chlorine, which would produce a chromophore showing maximum absorbance at 511 and 551nm and detected by a micro spectrometer detector...

Most drinking water industries are closely examining options to maintain a certain level of disinfectant residual through the entire distribution system. Chlorine dioxide is one of the promising disinfectants that is usually used as a secondary disinfectant, whereas the selection of the proper monitoring analytical technique to ensure disinfection and regulatory compliance has been debated within the industry. This research endeavored to objectively compare the performance of commercially available analytical techniques used for chlorine dioxide measurements (namely, chronoamperometry, DPD (N,N-diethyl-p-phenylenediamine), Lissamine Green B (LGB WET) and amperometric titration), to determine the superior technique...

UNLABELLED: Chlorine is a principal disinfectant for food and environmental sanitation. Monitoring of free available chlorine (FAC) is essential for ensuring the efficacy of food disinfection processes that rely on chlorine. N,N-diethyl-p-phenylenediamine (DPD) is commonly used for FAC monitoring. However, here, we show that upon contact with bovine serum albumin (BSA) or broiler carcasses, chlorite (HClO2 )-based sanitizers acquire a pink colour, which can interfere with measurement of oxidized DPD absorbance at 513-550 nm...

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...