P-dimethylaminobenzaldehyde Research Articles

Spectrofluorimetric determination of acetone in water samples with solid-phase extraction and a new benzaldehyde derivative

A new method is described for acetone (C(CH3)2O) determination in water samples. The method is based on the reaction with 4-(dimethylamino)benzaldehyde (DMAB) in dimethyl sulfoxide (DMSO) in slightly basic medium, resulting in a highly fluorescent compound with fluorescent wavelengths undisturbed by other common fluorescent compounds. Experimental conditions were optimized (reagents concentrations, reaction time) to reach optimal sensitivity. For the analysis of aqueous samples, a preconcentration step of acetone by solid-phase extraction (SPE) followed by an elution step in DMSO was optimized using Isolute ENV + columns. A highly satisfactory low detection limit of 0.014 μM (0.8 μg L−1) was achieved by combining these two steps, with a linear range from 0.048 to 5 μM and relative standard deviations between 5.7 % and 6.9 %. The protocol was validated on complex real water samples such as river water and wastewater, and our fluorimetric method with DMAB was in good agreement with the reference LC-UV method with DNPH.

A novel Ni-complex nanocatalyst for efficient electrochemical oxidation of alcohol in alkaline medium: Mechanism and DFT study

A novel catalyst based on nanoparticles of Ni(II) complex was developed to enhance the activity toward alcohol oxidation and hence its possible application in direct alcohol fuel cells (DAFCs). The [NiII(ABP)2] complex was formed in a molar ratio 1(Ni):2(ABP), where (ABP) was synthesized based on 4-(Dimethylamino)benzaldehyde (DMBA), 4-Aminoantipyrine (AAP) and 2-aminophenol (AP) through two condensation steps. Several characterization techniques were used to evaluate the structure of the synthesized compounds, such as elemental analysis, mass, FTIR, UV–Vis, 1HNMR , magnetic, molar conductance and XRD. Transmission and scanning electron microscope (TEM and SEM) images of separated [NiII(ABP)2] complex revealed particles with a size lower than 26 nm. SEM for [NiII(ABP)2]/GCE before and after ethanol oxidation was performed along with EDX and mapping techniques. The computational DFT (density functional theory) calculations supported the octahedral geometry shape of the prepared [NiII(ABP)2] chelate. Several octahedral structures involved in a purposed mechanism were studied using DFT to show the expected optimized shapes formed during ethanol oxidation. Also, the alcohol adsorption simulation was performed using Dmol3 numerical DFT modules to calculate the adsorption energy of alcohols on nickel complex surface. Additionally, the activity toward oxidation of alcohols with different sizes and stereochemistry (methanol, ethanol, propanol, and isopropanol) was investigated in an alkaline medium. The electrode activity was represented for each alcohol as a function of anodic oxidation current. Whereas the electrode achieved 14, 26, 6, and 4 mA cm−2 for methanol, ethanol, propanol, and isopropanol, respectively. Moreover, several parameters were calculated to judge the electrode performance, like diffusion coefficient, catalytic rate constant, stability, Tafel slope, and charge transfer resistance. The theoretical calculations and the experimental findings strongly correlate with each other, where Ni-complex showed the greatest catalytic activity toward ethanol oxidation.

A Spectrophotometric Determination of Amlodipine Drug in Pharmaceutical Preparations Using 2, 6-Dihydroxybenzoic Acid Reagent

In this study, a delicate, exact, and efficient colorimetric spectrophotometric technique was created for the assessment of Amlodipine in its unadulterated structure and in drug arrangements The strategy depends on the response of the optional amine in the medication with the carbonyl gathering in the natural reagent 2, 6 dihydroxy benzoic corrosive within the sight of p-dimethyl amino benzaldehyde to frame a yellow complex (Manich complex). The greatest absorbance was viewed as at 402 nm. Linearity was seen in the scope of 2-40 μg/mL, and the connection coefficient was viewed as 0.9909. The molar absorptivity was viewed as 1.392 × 104 L•mol-1•cm-1. It was observed that the shade of the item was steady and no massive change in absorbance was noticed for as long as 50 minutes a recuperation of 100.596% was gotten. The restriction of discovery (LOD) and cutoff of evaluation (LOQ) were viewed as 0.968 µg/mL and 3.228 µg/mL, individually. The %RSD was 4.32, which demonstrates the precision of the proposed strategy.

Fabrication of cationic microgels doped MnO2/Fe3O4 nanocomposites, and study of their photocatalytic performance and reusability in organic transformations

AbstractThis article reports, the fabrication of cationic microgel doped MnO2/Fe3O4 nanocomposites (CM@MnO2/Fe3O4) via free radical emulsion polymerization technique, and an economical and environmental friendly approach to some organic transformations, such as heterogeneous photocatalytic reduction of methylene blue (MB, toxic dye), para‐nitro phenol (PNP, harmful pollutant) and dimethyl amino benzaldehyde (DMAB, skin allergic reagent) in presence of UV light (38 W). First of all, three different crosslinked grades of cationic microgels (CMs) have been synthesized by using styrene, dimethyl acrylamide, cyclohexyl methacrylate, [2‐(acryloyloxy)ethyl] trimethylammonium chloride and N‐hydroxymethyl acrylamide monomers by taking different amounts of N‐hydroxymethyl acrylamide, and keeping the other monomers in fixed quantities. Further, all the grades of CMs have been doped by bimetallic MnO2/Fe3O4 nanoparticles, through hydrothermal method. Fabrication of CMs and CM@MnO2/Fe3O4 nanocomposites has been confirmed by the characteristic peaks observed in FT‐IR spectral analysis and their thermal stability has been evidenced by thermogravimetric analysis. TEM and DLS analyses have revealed their particular size. The surface morphology of CMs and CM@MnO2/Fe3O4 nanocomposites has been visualized by scanning electrode microscope analysis. The nanocomposites have effectively and efficiently catalyzed the reduction reactions of MB, PNP, and DMAB, in presence of UV light, by 98%, 98%, and 86%, respectively. The photocatalysts have been reused up to eight cycles without any loss of their catalytic activity. The photocatalytic reductions have also been studied for their kinetics, and exhibited pseudo first order kinetics (kapp, 10−2 min−1).

Fabrication and Characterization of Sulfonated Carbon Materials and Chitosan-Derived Functioned Carbon via Schiff’s Base Process for Separation Purposes

The Schiff bases reaction is applied to form various functioned carbon structures using renewable carbon from waste sources, Chitosan, 4-Amino-3-hydroxy-napthalene-1-sulphnic acid, and dimethyl amino benzaldehyde as starting materials. The formed functioned carbons were characterized by TEM, FTIR, XRD, and surface area analysis to assess their morphology, structure, porosity, and surface functional groups. In addition, the chromatographic-based thermodynamic analysis is applied to evaluate the surface energy and thermodynamic parameters during the separation of hydrocarbon species. Results indicated the formation of various carbon structures in convex-like shapes with diameters between 600 nm and 1500 nm, including side-building edges of diameter between 100 nm and 316 nm. The formed functioned carbon surfaces are rich with O-H, N=C, C=C, C=O, and C=S groups, as indicated by the FTIR. The function carbons are named carbon coated with Chitosan-derived covalent organic layer (C@Chitosan-COL) as well as Schiff’s base-derived sulfonated carbon (Schiff’s-C-S) in relation to the applied starting materials. The chromatographic-based thermodynamic analysis showed that the entropy changes of adsorption (ΔSA) increased with increasing chain length demonstrating less random movement and higher adsorption in both materials. The fabricated C@Chitosan-COL and Schiff’s-C-S showed an efficient separation of hydrocarbon mixture including n-Nonane, n-Decane, n-Undecane, and n-Dodecane.

Quick catalytic responsive chitosan flakes@Ag/CuO nanocomposites in organic synthesis and environmental remediation

This report deals with polymeric microgel of chitosan flakes (CF) for catalytic applications of bimetallic Ag/CuO nanoparticles (NPs). Nanocomposites, based on fabricated chitosan flakes, act as nanocatalyst and are used for swift chemical reduction of methylene blue (MB), para-nitro phenol (PNP) and dimethyl amino-benzaldehyde (DMAB) in presence of sodium borohydride or UV light. In our present work N-hydroxyl methyl acrylamide, instead of the traditional divinylic cross linker, has been employed as monomer as well as cross linker for the synthesis of chitosan flakes. The fabricated chitosan flakes have been doped with Ag/CuO NPs to yield nanocomposites. Three grades of nanocomposites have been synthesized by varying the amounts of N-hydroxyl methyl acrylamide, to optimize the crosslinking and suitable network, to yield stabilized NPs. FT-IR, XRD, TGA, SEM, TEM, EDX, DLS and Ultraviolet-Visible (UV-Vis.) spectroscopic characterization techniques have been performed to establish the polymeric chitosan flakes and nanocomposites. When the nanocomposites are employed as catalysts, the percentages of reduction of MB, PNP and DMAB, using sodium borohydride (NaBH4) or presence of UV-light, are over 90%, with lesser reaction time. The catalytic reduction in case of NaBH4 exhibits pseudo first order kinetics and the corresponding rate constant (kapp) values have been determined.

Determination of hydrazine in air by liquid chromatography/tandem mass spectrometry combined with precolumn derivatization.

In this study, we developed a determination method for hydrazine in the air. Hydrazine was derivatized with p-dimethyl amino benzaldehyde (DBA) to yield p-dimethylaminobenzalazine, which was subjected to liquid chromatography-electrospray tandem mass spectrometry (LC/MS/MS) analysis. The derivative exhibited good sensitivity in the LC/MS/MS analysis, and its instrument detection limit and instrument quantification limit were 0.003 and 0.008ng/mL, respectively. The air sample was collected using an air sampler equipped with a peristaltic pump at 0.2L/min for 8h. We demonstrated that a silica cartridge impregnated with DBA and 1,2-bis(4-pyridyl) ethylene can collect hydrazine in the air stably. The mean recovery rates in outdoor and indoor locations were 97.6% and 92.4%, respectively. Further, the method detection and quantification limits were 0.1 and 0.4ng/m3, respectively. The proposed method does not require any pretreatment and/or concentration step, enabling high-throughput analyses.

Phytochemical Investigation, In silico/In vivo Analgesic, and Anti-inflammatory Assessment of the Egyptian Cassia occidentalis L.

Cassia occidentalis L., from Fabaceae family phytochemical screening, revealed several biologically active principles mainly flavonoids and anthraquinones. GLC analysis of the lipoidal matter afforded 12 hydrocarbons: 9-dodecyl-tetradecahydro-anthracene (48.97 %), 9-dodecyl-tetradecahydro-phenanthrene (14.43 %), and 6 sterols/triterpenes: isojaspisterol (11.99%) and fatty acids were palmitic acid (50 %), and Linoleic acid (16.06%). Column chromatography led to the isolation of fifteen compounds (1–15), elucidated using spectroscopic evidence. First report of undecanoic acid (4) from the family Fabaceae, while p-dimethyl amino-benzaldehyde (15) was first time isolated from a natural origin. Eight compounds isolated for the first time from C. occidentalis L.; β-amyrin (1), β-sitosterol (2), stigmasterol (3), camphor (5), lupeol (6), chrysin (7), pectolinargenin (8), and 1, 2, 5-trihydroxy anthraquinone (14) besides five known compounds previously isolated; apigenin (9), kaempferol (10), chrysophanol (11), physcion (12), and aloe-emodin (13). In-vivo evaluation of anti-inflammatory and analgesic effects of C. occidentalis L. extracts where the n-butanol and total extracts showed the highest activities. The percentage of the inhibitory effect of the n-butanol extract was 29.7 at a dose of 400 mg/Kg. Furthermore, identified phytoconstituents were docked into the active sites of enzymes nAChRs, COX-1, and COX-2 to evaluate binding affinity. Phyto-compounds Physcion, aloe-emodin, and chrysophanol were found to have a good affinity for targeted receptors compared to co-crystalized inhibitors, validating the analgesic and anti-inflammatory effects of the phytochemicals.

Standardization of Methodology to Determine Nitrogen, Total Reducing Sugar, Crude Lipid and Urea Content in Panchgavya Formulation

The present study was conducted ICAR-National Dairy Research Institute, Karnal, Haryana, India during the year 2016−2020 to standardize the methodology to analyse the composition of panchgavya. Direct raw ingredients (milk urine and dung) were collected from live stock research centre, NDRI Karnal while indirect raw ingredients curd and ghee were prepared in laboratory. Panchgavya was prepared in three ratios i.e. RA, RB and RC by changing the level of urine and dung in final formulation. The methods for determination of nitrogen, crude lipid, reducing sugar and urea in panchgavya formulation were standardized. For all the analysis first theoretical value was calculated based on their percent in raw materials and experimental value was compared with it. Effect of sample weight and different methods to analyse composition was compared. In conclusion, it was found that Kjeldahl method for nitrogen content, Mojonnier acid digestion method for crude lipid, colorimetric method for lactose and DMAB (p- dimethyl amino benzaldehyde) for urea can be used as standard methods in the panchgavya formulation.

Development and validation of a new analytical method for determination of linagliptin in bulk by visible spectrophotometer

A simple, economical, and specific analytical method has been developed for determining and validating linagliptin (LNG) in bulk. This method is based on a condensation reaction between a primary amine in LNG and an aldehyde group in P-dimethylaminobenzaldehyde (PDAB) to form the yellow Schiff base with a wavelength of 407 nm. The optimum experimental conditions for the formulation of the colored complex have been studied. The optimum conditions were 1 mL of 5% w/v reagent solution with methanol and distilled water as a solvent for both PDAB, LNG respectively, also adding 2 mL of HCl as an acidic medium, heating to 70–75 °C on a water bath for 35 min. Furthermore, the stoichiometry of the reaction has been studied according to Job’s and Molar ratio method which was expressing 1:1 for LNG and PDAB. The researcher modified the method. The results show that the linearity in the concentration range (5–45 µg/mL) with correlation coefficient R2 = 0.9989 with percent recovery (99.46–100.8%) and RSD was less than 2%, LOD and LOQ 1.5815 − 4.7924 μg/mL respectively. This method can show high quality and there is no significant interference with excipients and in pharmaceutical forms. None of the studies showed the development of this method before.

Spectrophotometric method for the Determination of Sulfathiazole Drug by Schiff's base Formation

This research involves the development of simple, sensitive and rapid spectrophotometric method for determination of sulfathiazole (STHZ) in aqueous solution. The method is based on the Schiff's base formation between the primary amino group of sulfathiazole and aldehyde group of the p-dimethyl aminobenzaldehyde reagent (p-DMAB) to produce a yellow colored complex having maximum absorption at 451 nm at pH 2.2. Beer's law is obeyed in the concentration range 2-24μg/ml of sulfathiazole , with a molar absorptivity 11259 L.mol-1.cm-1 and sandal index of 0.023 μg.cm-2 . The average recovery is 99.925%, relative standard deviation 0.68-0.81% and D.L of 0.1534 μg/ml . This method has been applied successfully to determination of sulfathiazole in veterinary injection liquid solution (bio prime).

Diazotized reagent for spectrophotometric determination of glyphosate pesticide in environmental and agricultural samples

A new sensitive spectrophotometric method for the determination of glyphosate herbicide in environmental and agricultural samples is developed. The reaction is based on diazotization followed by coupling of glyphosate with p-dimethyl amino benzaldehyde. The resulted complex absorption spectra was observed at λmax = 420 nm. The effects of other metal ions and pesticides were also tested for selective determination of glyphosate. The analytical parameters were optimized and have been successfully applied for determination of glyphosate in various environmental samples such as soil, water and vegetables. This method has a lower limit detection of 6 μg of glyphosate. Beer's law is obeyed over the concentration range of 6.0 μg–24.0 μg glyphosate in 25 mL of the final solution at 420 nm. The standard deviation and relative standard deviation calculated are 0.0055 and 1.023, respectively. The molar absorptivity of the colored system is 1.91 × 1010 L mol−1cm−1 and Sandell's sensitivity is found 0.408 × 10−5 μg cm−2. The proposed method is simple, sensitive, highly reproducible and time saving as compare to those complicated time consuming methods.

A Green Analytical Methodology for Detecting Adulteration in Automotive Urea-SCR Products Using Microfluidic-Paper Analytical Devices

The application of urea-based selective catalytic reduction products (i.e., Urea-SCR) provides a reduction of NOx and, therefore, minimizes pollution emissions from vehicles fueled by diesel. Such products can be easily found in the market; however, they are often susceptible to adulteration, mainly in terms of the urea content and dilution with non-mineralized water. In this study, we propose a simple, low-cost, disposable, and straightforward paper-based microfluidic device for the quality-control of Urea-SCR products for the first time by quantifying urea and water hardness simultaneously via colorimetric reactions using a small volume of sample. 4-(dimethylamino)benzaldehyde and Eriochrome T were used as colorimetric indicators for urea and water hardness determination, respectively. Each reagent (1.5 µL) was combined with 6 µL of sample for analysis, contributing to an expressive reduction of waste generation. Digital images of the µPAD were obtained, and linear relations between color intensity and urea and Ca2+ and Mg2+ concentrations in the range of 0.2 to 1.0% and 0.1 to 3.5 mmol L−1 were obtained with a correlation coefficient higher than 0.99. Recovery experiments were employed to evaluate the accuracy of the methodology, revealing suitable values between 91.5 and 115%. Brazilian Urea-SCR samples were acquired from different distributors and submitted to the proposed procedure to evaluate its applicability. The application of microfluidic paper-based devices with colorimetric reactions enables the quality control of Urea-SCR products with high accuracy, portability, low consumption of reagents, and no generation of toxic residues; thereby contributing to the green analytical chemistry field.

Simultaneous determination of indole metabolites of tryptophan in rat feces by chemical labeling assisted liquid chromatography-tandem mass spectrometry

As the connecting part of diet and host physiology, intestinal microbes can convert the ingested diet into a huge number of physiologically active small molecules. Indole metabolites of tryptophan are precursors or signal molecules for many biologically active substances, which are involved in serotonin and microbial catabolism pathways. To understand the influence of tryptophan metabolism in the intestinal environment on the neurological and immune systems at the molecular level, it is important to establish a high-coverage analytical method to comprehensively analyze the metabolites involved in tryptophan metabolism. However, due to a small molecular weight and poor response during mass spectrometry analysis, as well as weak retention on the reversed-phase chromatography, determination of indole metabolites of tryptophan is challenging. Here, we proposed a method for the simultaneous determination of 20 indole metabolites of tryptophan in a single run on reversed-phase chromatography by chemical labeling coupled to liquid chromatography-tandem mass spectrometry analysis. 4-(Dimethylamino)benzaldehyde (DMAB) was used for the labeling of indole metabolites of tryptophan, which could significantly improve the detection sensitivities and retention of these metabolites on reversed-phase chromatography. With the developed method, we realized the sensitive detection and comprehensive analysis of 15 endogenous indole metabolites of tryptophan in rat feces samples with functional dyspepsia intervention by acupuncture. The developed method offers a useful tool for studying tryptophan metabolism-related diseases.

Vibrational Dynamics in crystalline 4-(dimethylamino) benzaldehyde: Inelastic Neutron Scattering and Periodic DFT Study.

The structure and dynamics of crystalline 4-(dimethylamino) benzaldehyde, 4DMAB, are assessed through INS spectroscopy combined with periodic DFT calculations. The excellent agreement between experimental and calculated spectra is the basis for a reliable assignment of INS bands. The external phonon modes of crystalline 4DMAB are quite well described by the simulated spectrum, as well as the modes involving low-frequency molecular vibrations. Crystal field splitting is predicted and observed for the modes assigned to the dimethylamino group. Concerning the torsional motion of methyl groups, four individual bands are identified and assigned to specific methyl groups in the asymmetric unit. The torsional frequencies of the four methyl groups in the asymmetric unit fall in a region of ca. 190 ± 20 cm−1, close to the range of values observed for methyl groups bonding to unsaturated carbon atoms. The hybridization state of the X atom in X-CH3 seems to play a key role in determining the methyl torsional frequency.

Microwave assisted extraction of antiplasmodial and antioxidant limonoids from Trichilia roka (chiov) Meliaceae)

Trichilia roka (Chiov) is a medicinal plant from Meliaceae family. It is recognized in traditional medicine for its innumerable therapeutic properties. Limonoids, the main constituents of the root bark of this plant, is known for its antioxidant and antiplasmodial activities. To obtain an improved yield of these bioactive compounds from T. roka and reduce extraction time, solvent and energy required, it is of utmost importance to adopt innovative approaches such as microwave-assisted extraction. Microwave was attempted, as compared with the conventional mechanical agitation method to extract bioactive limonoids and quantify them through colorimetric quantification method using 4(dimethyl amino) benzaldehyde (DMAB). The antiplasmodial activity was evaluated against the intraerythrocytic stages of cultured Plasmodium falciparum using a phenotypic approach, and the antioxidant property was evaluated in vitro using DPPH radical-scavenging and β-carotene-linoleate model systems respectively. Three limonoids and were isolated from Trichilia roka (Chiov) root bark labelled RA, RO and RY. The microwave extraction yields were 115.895 mgRUBE/gDW for limonoids. The isolated compounds exhibited good antioxidant activities than crude extracts with IC50 values of 2.59 10-3 , 2.26 10-3 and 1.79 10-3 mg/mL respectively compared to crude extract IC50 values of 2. 10-2 mg/mL. The in vivo antiplasmodial test of the hydromethanolic microwave extracts showed during the five treatment days the decreasing of the parasitaemia for doses 100 mg/kg, 200 mg/kg and 500 mg/kg with inhibition percentages of 82.75, 84.84 and 87.8 respectively.

Anticorrosive Effects of Derivatives of 4-{[4-(Dimethylamino) Benzylidene]amino}-1,2,4-Triazole on 316 Stainless Steel in HCl Medium: Experimental and Computational Study

Inhibiting potentials of three Schiff bases derived from 4-(dimethylamino)benzaldehyde, namely 5-(chloromethyl)-4-{[4-(dimethylamino)benzylidene] amine}-4H-1,2,4-triazole-3-thiol (CDTT), 4-{[4-(dimethylamino)benzylidene]amine}-5-phenyl-4H-1,2,4-triazole-3-thiol (DPhTT) and 4-{[4-(dimethylamino)benzylidene]amine}-5-pyridyn-4-yl-4H-1,2,4-triazole-3-thiol (DPyTT) on the corrosion of 316 stainless steel (316 SS) in 2M HCl were evaluated using weight-loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods at different inhibitor concentrations (5 to 500 ppm) and different temperatures (30 to 60 °C). DPhTT displayed a maximum inhibiting performance of 94.21% at 500 ppm at 30°C. The inhibitors CDTT and DPyTT showed inhibition efficiencies of 85.38% and 85.23% under similar conditions. All three inhibitors inhibited both cathodic and anodic corrosion processes. The enthalpies of activation for DPhTT, CDTT and DPyTT were 22.85, 36.23 and 50.86 kJ/mol, respectively, for 500 ppm solutions suggesting endothermic nature of the process. Adsorption of the inhibitors on the surface of the alloy was compatible with the Langmuir isotherm. Thermodynamic parameters of adsorption indicated that adsorption is primarily performed through chemisorption. The findings of EIS confirmed the formation of a chemisorbed film on the surface of the alloy. The scanning electron microscopy (SEM) and energy-dispersive x-ray studies (EDS) provided more evidence of increased corrosion resistance of 316 SS in the presence of inhibitors. Density functional theory (DFT) calculations have confirmed the experimental findings.

Development and Validation of Highly Sensitive Spectrophotometric Methods for Cefpirome Determination in Pharmaceutical Dosage Forms

Quantitative spectrophotometric determination of cefpirome in pure and pharmaceutical dosage has been developed. Method I produces a pink-coloured chromogen peak at λmax 510 nm by reacting diazotized cefpirome drugs with diphenylamine (DPA) in a neutral medium. Method II obtained of a coloured Schiff bases when cefpirome reacts with alcoholic p-dimethylaminobenzaldehyde (PDAB) to produce a yellow-coloured chromogen with a maximum absorption wavelength of 415 nm. In both methods I and II, Beer’s law is followed in the concentration ranges of 0.3-3.0 and 0.5-5.0 μg/mL, respectively, with molar absorptivity of 5.13 × 104 and 2.54 × 104 for each form. At three separate concentrations, intra-day and inter-day (RSD) and relative error (RE) are measured. The current methods are simple, reliable, inexpensive, speedy and highly reproducible and have been tested in broad range of pharmaceutical formulations with statistical comparisons to reference methods.

Synthesis and Electronic Transitions of the Dye Based on 1-{2-[4-(3-Hydroxy-2-oxo-2H-chromen-4-yl)phenyl]-2-oxoethyl}-4-methylpyridinium Bromide

4-[4-(2-Bromoacetyl)phenyl]-3-hydroxy-2H-chromen-2-one reacted with pyridine and 4-methylpyridine to give the corresponding quaternary pyridinium salts. The condensation of 1-{2-[4-(3-hydroxy-2-oxo-2H-chromen-4-yl)phenyl]-2-oxoethyl}-4-methylpyridinium bromide with 4-(dimethylamino)benzaldehyde afforded a new biscyanine dye whose electronic spectrum showed two absorption maxima originating from interactions of chromophores. The nature of electronic transitions in the dye molecule was analyzed by quantum chemical calculations.

Micelles Mediated Zone Fluidics Method for Hydrazine Determination in Environmental Samples.

An automated flow method for the determination of hydrazine based on the concept of zone-fluidics has been developed. The analyte reacts under flow conditions with p-dimethylamino benzaldehyde (25 mmol L−1) in micellar medium (100 mmol L−1 SDS) to form a stable derivative (460 nm). Micelles mediated catalysis excludes the use of highly acidic environment typical for this kind of reaction. Following careful examination of chemical and instrumental variables, the method allows the determination of hydrazine at the low micromolar level (0.3–10 μmol L−1) in water samples. Real sample analyses (drinking and boiler feed water) resulted in satisfactory results in terms of accuracy with the percent recoveries being in the range of 82–114%.