Synthesis of some antipyrinylazo and thiazolylazo compounds with pentan-2,4-dione and their reactions with metal ions

The reagents were synthesized by using pentan-2,4-dione as the coupling component with diazotized 4-aminoantipyrine or 2-aminothiazole. Two kinds of azo compounds were obtained under different conditions: 1-(4-antipyrinylazo)-1-(4-antipyrinylhydrazino)propan-2-one (Azonol A-1) and 3-(4-antipyrinylazo)pentan-2,4-dione (Azonol A-2) from 4-aminoantipyrine, and 1-(2-thiazolylazo)-1-(2-thiazolylhydrazino)propan-2-one (TAA-1) and 3-(2-thiazolylazo)pentan-2,4-dione (TAA-2) from 2-aminothiazole. The structure of Azonol A-1 was determined by single-crystal x-ray crystallography. The reactions of these reagents with various metal ions were examined. Azonol A-1 and TAA-1 form metal chelates at low pH values. Azonol A-1 is useful as a metallochromic indicator in titrations of bismuth with EDTA at pH 0.5–2, and as a spectrophotometric reagent for copper (II) (0.2–1.5 mg l^?1) at pH 0.3–1.2.     

Oxidation of butane-1,3-, butane-1,4-, 2-methyl pentane-2,4- and 3-methyl pentane-2,4-diols by cerium(IV) in aqueous acidic medium catalyzed by rhodium(III)

The oxidation kinetics of butane-1,3-diol, butane-1,4-diol, 2-methyl pentane-2,4-diol and 3-methyl pentane-2,4-diol with cerium(IV) catalyzed by rhodium(III) in aqueous sulfuric acid showed a peculiar nature with respect to the variation in oxidant concentration, such that the reaction follows first-order kinetics in [Ce(IV)] at low [Ce(IV)] and then reaches a maximum with increasing [Ce(IV)], beyond which further increase in the oxidant concentration retards the rate. The rate shows direct proportionality with respect to [diol] at low concentrations, becoming independent of [diol] at higher concentrations. The rate is first order in catalyst. Retarding effects are observed when [H⁺] and [Ce(III)] are increased, while [Cl⁻] and hence ionic strength have a positive effect on the rate. Spectroscopic studies confirmed that the primary hydroxyl groups in butane-1,3-diol and butane-1,4-diol resulted in the formation of 3-hydroxy butanal and 4-hydroxy butanal, respectively. In the case of oxidation of the secondary hydroxyl groups in 2-methyl pentane-2,4-diol and 3-methyl pentane-2,4-diol, the products of oxidation were 4-hydroxy-4-methyl pentan-2-one and 4-hydroxy-3-methyl pentan-2-one, respectively.     

Using 2,4 DNPH-PVC membrane sensors for indirect determination of formaldehyde in urea glue and wastewater

Three simple, rapid, and sensitive ion-selective electrodes for indirect determination of free formaldehyde in urea glue and wastewater have been developed. The methods are based on the formation of the membrane sensors 2,4-dinitrophenylhydrazine-phosphtungestic acid (DNPH-PTA), 2,4-dinitrophenylhydrazine-phosphomolybdic acid (DNPH-PMA), and 2,4-dinitrophenylhydrazine-tetraphenylborate (DNPH-TPB) as neutral carriers. The sensors are stable and show fast potential responses of 30?s, and near-Nernstian cationic slopes of 56.2?±?0.5, 54.3?±?0.5, and 53.8?±?0.4?mV per decade of activity between pH 0.5 and 3.5 over a wide range of 2,4-dinitrophenylhydrazine concentrations (1?×?10^?5 to 1?×?10^?2?M). These sensors were used for indirect determination of formaldehyde over concentration range (1?×?10^?4 to 1?×?10^?1?M). The selectivity coefficients of the developed sensors indicate excellent selectivity for 2,4 DNPH over a large number of organic and inorganic species. The mediator o-nitrophenyloctyl ether has a significant affect on the lifetime of the fabricated sensors. The analytical applications of the proposed sensors showed good results for indirect determination of formaldehyde in formaldehyde solutions, wastewater solutions, and free formaldehyde in urea-formaldehyde liquid and powder glues. The results were compared favourably with that obtained by ASTM, colorimetric, and British Standard methods.     

Flow Injection Spectrophotometric Determination of 2,4‐D Herbicide

2,4‐Dichlorophenoxy acetic acid herbicide is spectrophotometrically determined by diazotization method in a flow injection assembly. The method is based on base hydrolysis of herbicides. The hydrolyzed product 2,4‐dichlorophenol is reacted with diazotized sulfanilic acid. The absorbance of the resulting coloured product was measured at 480 nm. The calibration graph is linear over the range of 0.2–20 μgmL^?1, with a relative standard deviation of (RSD) of 7.2% and sample throughput of 90 samples h^?1. The % recovery for determination of 2,4‐dichlorophenoxy acetic acid was found to be 92.0–95.3%. The method is easy, simple and faster than the established chromatographic method. The method was applied for determination of 2,4‐dichlorophenoxy acetic acid herbicide in commercial formulations and for residue determination in fruits and food samples.     

Direct and Derivative Spectrophotometric Determination of Zinc with 2,4-Dihydroxybenzaldehyde Isonicotinoyl Hydrazone in Potable Water and Pharmaceutical Samples

A simple and sensitive spectrophotometric method is developed for the determination of zinc in aqueous solutions. The metal ion forms a greenish-yellow colored complex with 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone (2,4-DHBINH) in the pH range of 4–10. The complex shows maximum absorbance at 390 nm and in the pH range of 6–8. Beer's law is obeyed in the range 0.10–1.50 μg/mL of Zn(II). The molar absorptivity and Sandell's sensitivity are 3.55 × 10⁴ mol⁻¹ cm⁻¹ and 0.0016 μg/cm², respectively. The composition of the complex is 1 : 1. The effect of interfering ions has been studied, and the method was applied to the determination of zinc(II) in potable water and pharmaceutical samples. A fast derivative spectrophotometry method is also proposed for the determination of zinc in the range 0.06–1.60 μg/mL, which is more sensitive than the zero order method. __________ Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 9, 2005, pp. 933–937. Original Russian Text Copyright ? 2005 by Sivaramaiah, Raveendra Reddy. The text was submitted by the authors in English.     

A Comparative Study of Anti-Candida Activity and Phenolic Contents of the Calluses from Lythrum salicaria L. in Different Treatments

In the study, anti-Candida activity and phenol contents of Lythrum salicaria L. calli and wild species have been evaluated. The seeds of L. salicaria (Lythraceae), collected from Lahidjan City in the north of Iran, were cultured in Murashige and Skoog medium (MSM) with a supplement, gibberellin, to germinate. Callus inductions were performed from segments of seedling on MSM containing different concentrations of plant growth regulators, 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BAP). The activity of calluses extracts, wild plant, gallic acid, and 3,3′,4′-tri-O-methylellagic acid-4-O-β-d-glucopyranoside (TMEG) as the main phenolic compounds against Candida albicans was assessed using cup plate diffusion method. The total phenols contents of calli and wild plant extracts were analyzed using Folin–Ciocalteu reagent. The callus formation in MSM supplemented with various concentrations of 2,4-D and BAP were 0–100 %. Anti-Candida activity of callus extract which obtained from MSM supplemented with 2,4-D and BAP (1 mg?dm^?3) was similar to the wild plant extract. Minimum inhibitory concentration values of gallic acid and TMEG were obtained as 0.312 and 2.5 mg?cm^?3, respectively. Gallic acid equivalent values in all treatments were from 0 to 288 μg GAE mg^?1. Phenolic contents of plant aerial parts (331?±?3.7 μg GAE mg^?1) and the callus, which developed in MSM including 1 mg?dm^?3 of both 2,4-D and BAP, showed the same phenolic value and exhibited anti-Candida extract activity.     

Isotope effects—I: Hydrogen isotope effects in acetylacetone and its enol

Aspects of the effects of deuteriation on the properties of acetylacetone (pentan-2,4-dione) and its enol have been reinvestigated and new isotope effects have been sought in order to understand better the nature of the hydrogen bridge in the enol (1E). There is no substantial hydrogen isotope effect on the enthalpy of enolisation of 1 (contrary to Ref. 5) but there are unusually large isotope effects on v_max (contrary to Ref. 5) and on the band shape of the long wavelength ( ~ 37,000 cm^?1) UV absorption and on the ¹³C NMR chemical shift of the Cl(3) atoms in 1E. It is concluded that these and other properties of the enol 1E can be qualitatively explained if the hydrogen bridge in 1E is not quite symmetrical but has two symmetrically placed potential energy minima close together for the hydrogen atom leading to a lengthening of the O?O distance on deuteriation.     

Rapid and simple method for determination of hexabromocyclododecanes and other LC–MS–MS-amenable brominated flame retardants in fish

In this study, a novel analytical approach for simultaneous determination of hexabromocyclododecane isomers (HBCDs), tetrabromobisphenol A (TBBPA), three brominated phenols, and four hydroxylated derivatives of polybrominated diphenyl ethers (OH-PBDEs) was developed and validated for muscle tissue of both lean and fatty fish. The rapid, simple, and high-throughput sample-preparation procedure was based on acetonitrile extraction then purification by dispersive solid-phase extraction (d-SPE) with a combination of C₁₈ and primary–secondary amine (PSA) sorbents. Ultra-high performance liquid chromatography (UHPLC) coupled to tandem mass spectrometry (MS–MS) was used for identification and quantification of the analytes. Method recovery for both matrices ranged from 80 to 115 % with relative standard deviations (RSDs) <13 % for all analytes. Limits of quantification (LOQs) were in the range 0.1–1 μg kg^?1 wet weight. The validated method was used for analysis of brominated compounds in 32 fish and five bivalve samples collected from different European markets within the monitoring survey organized in the framework of the CONffIDENCE project. Of the 12 targeted analytes, only α-HBCD, 2,4-dibromophenol (2,4-DBP), and 2,4,6-tribromophenol (2,4,6-TBP) were quantified in the samples. α-HBCD was found in six fish samples (herring and mackerel) in the range of 0.8–2.5 μg kg^?1 wet weight. 2,4-DBP and 2,4,6-TBP were found in three blue mussel samples in the range of 19.6–43.5 and 2.3–7.5 μg kg^?1 wet weight, respectively.     

Fluorescent Detection of 2,4‐DNT and 2,4,6‐TNT in Aqueous Media by Using Simple Water‐Soluble Pyrene Derivatives

Pyrene‐containing water‐soluble probes for the fluorescent detection of nitroaromatic compounds (NACs), such as explosive components (2,4‐DNT and 2,4,6‐TNT) and herbicides (2,4‐dinitrocresol, 2,4‐DNOC), in aqueous media are reported. In the probes, the introduction of surface‐active hydrophilic “heads” at the periphery of lipophilic (i.e., hydrophobic) pyrene “tails” resulted in the formation of highly fluorescent micelle‐like aggregates/pre‐associates in aqueous solutions at concentrations of ≤10^?5 m . The enhanced fluorescence quenching of the herein reported architectures is achieved in the presence of ultra‐trace amounts of TNT or 2,4‐DNT with values of Stern–Volmer quenching constant close to 1×10⁵ m ^?1 and a detection limit as low as 182 ppb. The most hydrophilic probes demonstrated higher response to 2,4‐DNT over TNT. Filter paper test strips impregnated with 1×10^?5 m solutions of the probes were able to detect TNT, 2,4‐DNT, and other NACs at levels as low as 50 ppb in water.     

Synthesis,characterization and application of dummy-template molecularly imprinted microspheres for 2,4-d butyl ester

Dummy-template molecularly imprinted microspheres were synthesized via precipitation polymerization employing 2,4-D isooctyl ester as the template molecule instead of 2,4-D butyl ester, while methacrylic acid and divinylbenzene were used as functional monomer and cross-linker in acetonitrile or a mixture of acetonitrile and toluene. The microspheres were characterized by scanning electron microscopy, laser particle size analyzer and fourier transform infrared spectrometry. Binding capacity experiment showed that the molecularly imprinted polymers prepared in a mixture of acetonitrile and toluene had a high binding capacity. The performance of microspheres was further assessed by equilibrium binding and kinetic adsorption experiments. The results showed that the apparent maximum adsorption reached up to 1.35 mg·g^?1 within 10 min. Based on the dummy-template microspheres, a molecularly imprinted solid phase extraction-gas chromatography method was developed for the selective analysis of 2,4-D butyl ester in soil samples. The mean recoveries of 2,4-D butyl ester from blank soil samples ranged from 85.9 to 99.3% with relative standard deviations of 4.5–14.3% (n = 5). The limit of detection and the limit of quantification of 2,4-D butyl ester were 0.8 μg·kg^?1 and 2.3 μg·kg^?1, respectively.     

Substituent effects on enol nitrosation of 1,3‐diketones

The keto–enol tautomerism of 3‐chloro‐pentane‐2,4‐dione (ClPD) was studied in aqueous micellar solutions of cationic, anionic, and nonionic surfactants. The enol of ClPD tautomerizes rapidly in water to the equilibrium proportions of the keto form, K_E=0.55; whereas the keto–enol conversion of 3‐ethyl‐pentane‐2,4‐dione (EPD) is a much slower reaction than the enol nitrosation. Kinetics of enol –nitrosation of both ClPD and EPD in aqueous acid medium using nitrous acid shows first‐order dependence upon [ketone] and linear or curve relationships of the observed rate constant, k_o, as a function of [nitrite] or [H⁺]; the observed behavior depends on the molecular structure of diketone and varies with the experimental conditions. The reaction is strongly catalyzed by Cl^?, Br^?, or SCN^?, and the observed rate constant shows a curve dependence on [Br^?] or [SCN^?], which is more pronounced at high acidity. The results are consistent with a reaction mechanism in which the nitrosation occurs initially on the enol–oxygen and releasing a proton to form a chelate–nitrosyl complex intermediate in steady state. Fine differences on the mechanistic spectrum of enols nitrosation are considered on the basis of the molecular structure of the diketone. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 668–679, 2012     

A poly (4‐vinylpridine‐co‐ethylene glycol dimethacrylate) monolithic concentrator for in‐line concentration‐capillary electrophoresis analysis of phenols in water samples

A poly(4‐vinylpridine‐co‐ethylene glycol dimethacrylate) monolith was synthesized in a capillary and constructed as a concentrator for the in‐line polymeric monolith microextraction coupling with capillary electrophoresis. The integrated system was then used for the simultaneous determination of five trace phenols (2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2‐chlorophenol, and 2,4‐dichlorophenol) in water samples. The experimental parameters for in‐line solid‐phase extraction, such as composition and volume of the elution plug, pH of sample solution, and the time for sample loading were optimized. The sensitivity for the mixture of phenols (2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2‐chlorophenol, and 2,4‐dichlorophenol) enhanced to 615–2222 folds at the optimum condition was compared to the sensitivity for a normal hydrodynamic injection in capillary electrophoresis. Linearity ranged from concentration of 10–500 ng mL^?1(R² > 0.999) for all five phenols with the detection limits of 1.3–3.3 ng mL^?1. In tap, snow and Yangtze River water spiked with 20 ng mL^?1 and 200 ng mL^?1, respectively, the recoveries of 84–105% were obtained. It has been demonstrated that this work has great potential for the analysis of phenols in genuine water samples.     

Destruction of 2,4 Dichlorophenol in an Atmospheric Pressure Dielectric Barrier Discharge in Oxygen

The processes of degradation of 2,4-dichlorophenol (2,4-DCP) under the action of atmospheric pressure of dielectric barrier discharge (DBD) in oxygen were studied. It was shown that the degradation of 2,4-DCP proceeds efficiently. Degree of decomposition reaches 90%. The degradation kinetics of 2,4-DCP obeys the formal first-order kinetic law on concentration of 2,4-DCP. The effective rate constants depend weakly on the experimental conditions and are equal to ~0.2 s^?1. Based on experimental data, the energy efficiency of decomposition of 2,4-DCP was determined. Depending on the conditions, the energy efficiency was in the range of (8–90) × 10^?3 molecules per 100 eV. The composition of the products was studied by gas chromatography (GC), gas chromatography–mass spectrometry (GC–MS), energy-dispersive X-ray spectroscopy (EDX), attenuated total reflection-fourier transform infrared (ATR-FTIR) spectroscopy, electron spin resonance (ESR) spectroscopy and UV/Visible spectroscopy. It was shown that about ~20% of 2,4-DCP is converted to CO₂, while the other part forms an organic film on the reactor wall. The substance formed is close to the carboxylic acids in chemical composition and exhibits electrical conductivity and paramagnetic properties. Almost all of the chlorine contained in the 2,4-DCP is released into the gas phase. The active species of the afterglow react with liquid hexane, forming the products of its oxidation. Some assumptions regarding the pathway of the process are discussed.     

Synthesis of 4-acetyl-5(3)-amino-3(5)-methylpyrazoles and pyrazolo[3,4-d]pyrimidines from diacetylketeneN,S-acetal

Isomeric 4-acetyl-5-amino-3-methyl- and 4-acetyl-3-amino-5-methylpyrazoles (2, 3) were formed in the reaction of hydrazines with 3-[amino(methylthio)methylene]pentan-2,4-dione (1) (diacetylketeneN,S-acetal). Pyrazolo[3,4-d]pyrimidines (5a,b) were synthesized by condensation of 4-acetyl-5-amino-1,3-dimethylpyrazole (2a) with amide dimethylacetals followed by treatment with ammonium acetate. The structures of the compounds obtained were confirmed by¹³C and¹⁵N NMR spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1429–1433, August, 1993.     

Study of the solid phase extraction and spectrophotometric determination of nickel using 5-(4′-chlorophenylazo)-6-hydroxypyrimidine-2,4-dione in environmental samples

A rapid, sensitive and selective method for the determination of nickel based on the rapid reaction of nickel(II) with 5-(4′-chlorophenylazo)-6-hydroxypyrimidine-2,4-dione (CPAHPD) and the solid phase extraction of the Ni(II)–CPAHPD complex with C18 membrane disks has been developed. In the presence of pH 6.8 buffer solution and cetylpyridinium bromide (CPB) medium, CPAHPD reacts with nickel to form a red complex of a molar ratio of 1:1 (nickel to CPAHPD). This complex was enriched by solid phase extraction (SPE) with C18 membrane disks. An enrichment factor of 100 was obtained by elution of the complex from the disks with the minimal amount of isopentyl alcohol. The molar absorptivity and Sandell sensitivity of the complex was 3.11 × 10⁵ L mol^?1 cm^?1 and 0.0189 ng cm^?2, respectively at 549 nm in the measured solution. Beer's law was obeyed in the range of 0.01–0.37 μg mL^?1, while that obtained by Ringbom plot was in the range of 0.025–0.35 μg mL^?1. The detection and quantification limits were calculated and found to be 0.003 and 0.01 μg mL^?1. The proposed method was applied to the determination of nickel in water, food, biological and soil samples with good results.     

Vibrational Sum‐Frequency Generation Activity of a 2,4‐Dinitrophenyl Phospholipid Hybrid Bilayer: Retrieving Orientational Parameters from a DFT Analysis of Experimental Data

The vibrational nonlinear activity of films of 2,4‐dinitrophenyl phospholipid (DNP) at the solid interface is measured by sum‐frequency generation spectroscopy (SFG). Hybrid bilayers are formed by a Langmuir–Schaefer approach in which the lipid layer is physisorbed on top of a self‐assembled monolayer of dodecanethiol on Pt with the polar heads pointing out from the surface. The SFG response is investigated in two vibrational frequency domains, namely, 3050–2750 and 1375–1240 cm^?1. The first region probes the CH stretching modes of DNP films, and the latter explores the vibrational nonlinear activity of the 2,4‐dinitroaniline moiety of the polar head of the lipid. Analysis of the CH stretching vibrations suggests substantial conformational order of the aliphatic chains with only a few gauche defects. To reliably assign the detected SFG signals to specific molecular vibrations, DFT calculations of the IR and Raman activities of molecular models are performed and compared to experimental solid‐state spectra. This allows unambiguous assignment of the observed SFG vibrations to molecular modes localized on the 2,4‐dinitroaniline moiety of the polar head of DNP. Then, SFG spectra of DNP in the 1375–1240 cm^?1 frequency range are simulated and compared with experimental ones, and thus the 1,4‐axis of the 2,4‐dinitrophenyl head is estimated to have tilt and rotation angles of 45±5° and 0±30°, respectively.     

Diversity of supramolecular aggregation in copper(II) pentane-2,4-dionato compounds with methyl substituted 2-aminopyridines

Three copper(II) bis(pentane-2,4-dionato-κ ² O,O′) compounds with 2-amino-3-methylpyridine (2,3-ampy) (1), 2-amino-5-methylpyridine (2,5-ampy) (2), and 2-amino-4-methylpyridine (2,4-ampy) (3) were prepared by reaction of bis(pentane-2,4-dionato-κ ² O,O′)copper(II) with selected methyl substituted 2-aminopyridines. The coordination of Cu(II) in all three compounds is square pyramidal and intramolecular N–H?···?O hydrogen-bonding is present. X-ray crystallographic studies reveal different crystal aggregation influenced by a methyl substituent on pyridine. No intermolecular N–H?···?O hydrogen-bonding is present in 1. Intermolecular N–H?···?O hydrogen-bonding in 2 forms infinite chains and dimers are formed in 3. Extended 3-D aggregation was found in 2 via π–π and C–H?···?π (arene) interactions, while only chain formation was found in 1 and 3.     

Determination of Aroma Compounds from Alcoholic Beverages in Spiked Blood Samples by Means of Dynamic Headspace GC–MS

Some aroma compounds found in alcoholic beverages are characteristic of a certain beverage (i.e. 2,4-decadienoic acid ethyl ester is characteristic of pear spirit and 5-butyltetrahydro-4-methylfuran-2-on “whiskey lactone” is characteristic of aged spirits like whiskey). These substances were detectable in beverages but not in blood samples. The aim of this investigation was to find a sensitive sampling technique for aroma compounds in whole blood samples. This technique may be used in forensic toxicology for examination of drinking claims. The method comprises dynamic headspace sampling using a purge and trap concentrator, followed by quantitative gas chromatography–mass spectrometry (dynamic HS–GC–MS). The influence of sample preparation, trap adsorbents and sample temperature as well as desorption time and purge time on the quality of the analytical results were investigated. The following optimal parameters were determined: stirred and diluted whole blood sample without salt addition, use of Carbotrap C as trap material, sample temperature at 80 °C, desorption time 20 min and purge time 30 min. These optimal parameters were used for the determination of detection limits (LOD). The LOD of aroma compounds by means of dynamic headspace sampling were compared with the results of conventional sampling: the static headspace technique. Limits of detection for the aroma compounds with conventional static headspace GC are in the range 400–10,000 μg L^?1. Dynamic headspace–GC was found to be a more sensitive sampling technique for most of the aroma compounds investigated (e.g. C₄–C₈ ethyl esters, benzoic acid ethyl ester, linalool oxide and 4-ethylguaiacol) with detection limits between 1 and 50 μg L^?1, but there were also limits to the sampling of substances with lower volatility like decanoic acid ethyl ester, 2,4-decadienoic acid ethyl ester, eugenol and whiskey lactone with detection limits of about 1,000 μg L^?1.     

Sulfanylamide-containing coordination compounds of 3d-elements with 2,4-pentanedione bis-thiosemicarbazone and bis-4-phenylthiosemicarbazone

Thiosemicarbazide and 4-phenylthiosemicarbazide react in ethanol with 2,4-pentanedione in the presence of manganese, cobalt, nickel, copper, and zinc acetates hydrates and streptamin (Sf¹), sulfaethidole (Sf²), and sulfadimidine (Sf³) to form coordination compounds of the composition M(Sf^1–3)(L^1–2) · nH₂O (M = Mn, Co, Ni, Cu, Zn; H₂L¹ is 2,4-pentanedione bis-thiosemicarbazone, H₂L² is 2,4-pentanedione bis-4-phenylthiosemicarbazone; n = 0–6). All the complexes synthesized are monomeric. Thiosemicarbazones (H₂L¹ and H₂L²) behave as twice deprotonated S,N,N,S-tetradentate ligands, while sulfanylamides (Sf^1–3) act as monodentate ones. Thermolysis of these substances proceeds through the stages of dehydration (65–95°C) and complete thermal decomposition (430–560°C). It is found that the complex [Cu(Sf²)(L¹)] · 4H₂O in the concentration 10^?5 M inhibits the growth and fission of 100% cancer cells of the human myeloid leukemia (HL-60).     

New immunosensors for 2,4-D and 2,4,5-T pesticides determination

New immunosensors for 2-(2, 4-dichlorophenoxy) acetic acid (i.e. 2,4-D) and (2, 4, 5-trichlorophenoxy) acetic acid (i.e. 2,4,5-T) pesticide determination were developed using a non commercial antibody, hydrogen peroxide transducer and horseradish peroxidase as enzyme marker. The results show the full validity of these immunosensor devices, which were optimized using a ‘competition’ separation procedure. These immunosensors were also used to test pesticide recovery in common real matrices such as field grass, maize and wheat samples, for which good results were obtained. The immunosensors developed demonstrated a good selectivity versus different kinds of pesticides and may thus be considered as suitable devices for application to real matrices (LOD?=?8.0?×?10^?11?mol?L^?1; RSD%?=?5.2 for 2,4-D and LOD?=?2.8?×?10^?9?mol?L^?1; RSD%?=?6.1 for 2,4,5-T).