Spectrophotometric determination of metribuzin herbicide with p-dimethylamino-benzaldehyde using factorial designs for optimization of experimental variables

A new simple spectrophotometric method has been developed for the determination of metribuzin herbicide in formulations and potato samples. The method is based on the reaction of p-dimethylamino-benzaldehyde (DMAB) with sodium hydroxide via Cannizzaro’s reaction at 100 °C to form a p-dimethylaminobenzoic acid. The resultant p-dimethylaminobenzoic acid reacted with metribuzin herbicide in acidic media at 100 °C and the yellow colored product was measured at 455 nm. The reaction conditions and other analytical parameters were studied and optimized. A linear plot between absorbance and concentration over the range from 0.2 to 20 μg mL−1 was found with molar absorptivity of 2.1 × 104 L mol−1 cm−1. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.05 and 0.2 μg mL−1, respectively. The proposed method has been successfully applied for the analysis of commercial formulation and potato sample. The recoveries of the method were found to be in the range from 92.16 ± 0.06% to 96.66 ± 0.18%. Two level factorial designs of 23 and 22 were used to optimize all parameters, determine the influence of different parameters and their interactions on the final product formation

Flow injection spectrophotometric determination of glyphosate herbicide in wheat grains via condensation reaction with p-dimethylaminobenzaldehyde

A fast and sensitive method was developed for determination of glyphosate, using flow injection analysis. The analyte was converted to a photoactive product that shows maximum absorbance at 405 nm. Beer’s law was obeyed over a range of 0.7–20 μgmL–1. The limit of detection and quantification were found to be 0.20±0.01 and 0.70±0.02 μgmL–1 with a high sample throughput of 60 samples h–1. The investigation of interference effect shows that among the compounds studied, only aminomethyl phosphonic acid exhibits a signal enhancing effect when present in higher concentration ratio with the analyte and this can be assumed to be a limitation of the present method. The percentage recoveries and residue of glyphosate in wheat grains samples, were found in the range of 90.0 ± 0.6 % to 93.0 ± 0.6 % and 1.13 ± 0.009 μg g–1, respectively.Keywords: Glyphosate, photoactive, absorbance, flow injection analysis, residu

Photocatalytic assessed adsorptive removal of tinidazole from aqueous environment using reduced magnetic graphene oxide-bismuth oxychloride and its silver composite

Antibiotics (tinidazole (TNZ)) in wastewater, exhibit adverse effects on humans and ecosystem. The current study was aimed to synthesize photocatalysts mrGO/BiOCl and mrGO/BiOCl/Ag. mrGO was coupled with BiOCl by hydrothermal method and Ag was deposited over it. The synthesized mrGO/BiOCl and mrGO/BiOCl/Ag were confirmed by Pzc analysis (5.5 and 4.4 for mrGO/BiOCl and mrGO/BiOCl/Ag, respectively), surface area analysis (380 m2 g-1, 227.7 m2 g-1, 220 m2 g-1 for mrGO, mrGO/BiOCl and mrGO/BiOCl/Ag respectively), elemental analysis (Ag, O, Bi, Fe), surface morphology (rough ball like sphere of mrGO/BiOCl and cubic Ag nanoparticles in mrGO/BiOCl/Ag), functional groups and band gap (Eg) determination. The Eg was determined using KubelkaMunk equation as 3.5 and 2.8 eV for mrGO/BiOCl and mrGO/BiOCl/Ag respectively. During the adsorption study, the best experimental conditions for various operating parameters such as pH (2), contact time (5 min for mrGO/BiOCl and 10 min for mrGO/BiOCl/Ag under UV irradiation), TNZ concentration (18 mu gL-1) and catalyst dosage (0.001 g) were achieved. Kinetic study revealed that both composites followed pseudo second order kinetics (R2 = 0.9979 and 0.9986, respectively). Data of rGO/BiOCl was fitted to Freundlich adsorption model (R2 = 0.9687) and rGO/BiOCl/Ag fitted to Langmuir adsorption model (R2 = 0.9994). Moreover, thermodynamic parameters confirmed that a photodegradation phenomenon was spontaneous and exothermic. The results confirmed that rGO/BiOCl and rGO/BiOCl/Ag are appropriate composites for TNZ removal from the aqueous environment with removal efficiency of 97 and 24%, respectively

Preparation and characterization of uniform molecularly imprinted polymer beads for separation of triazine herbicides

Uniform molecularly imprinted polymer beads were synthesized by precipitation polymerization for separation of triazine herbicides. A series of imprinted polymers were prepared using ametryn as template and divinylbenzene as crosslinking monomer, in combination with three different functional monomers under different solvent conditions. Under optimized reaction conditions, we obtained uniform molecularly imprinted polymer microspheres that display favorable molecular binding selectivity for triazine herbicides. The imprinted polymer beads synthesized using methacrylic acid as functional monomer in a mixture of methyl ethyl ketone and heptane showed the best results in terms of particle size distribution and molecular selectivity. Compared with nonimprinted polymer microspheres, the imprinted microspheres displayed significantly higher binding for a group of triazine herbicides including atrazine, simazine, propazine, ametryn, prometryn, and terbutryn. For the first time, precipitation polymerization has been used to produce highly uniform imprinted microspheres suitable for affinity separation of triazine herbicides. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 201

Evaluation and statistical analysis of the modified QuEChERS method for the extraction of pinoxaden from environmental and agricultural samples

Abstract Background Green chemistry focuses on an efficient extraction strategy for pesticides from agricultural and environmental samples. QuEChERS (quick, easy, cheap, effective, rugged, and safe) method is used primarily, in the extraction of pesticides from food matrices. Certain modifications in the approach lead to better sensitivity and efficient extraction. This paper describes an analytical approach for spectrophotometric determination of pinoxaden herbicide in different matrices based on a modified QuEChERS method. Methods The original QuEChERS method was modified using different buffering media and different cleanup sorbents. Efficacy of different dispersive SPE sorbents for the cleanup was compared. The optimized conditions were applied for investigation of percent recovery and residue analysis. The presence of the residue was confirmed by employing two reported HPLC methods under optimized conditions. Statistical analysis of the data was accomplished to investigate the distribution of the subject analyte in soil. Results The average percent recovery of pinoxaden was found to be in the range of 77 ± 5% to 100 ± 2% for soil, 84 ± 2% to 98 ± 2% for water samples, and 79 ± 1% to 88 ± 1% for wheat grains. Good linearity with R 2 = 0.997 was achieved in acetate buffer system. Limits of detection of pinoxaden in soil, water, and wheat grain samples were found to be 0.6 μg/g, 0.48 μg/mL, and 0.31 μg/g, respectively, while limits of quantification in the above matrices were found to be 1.83 μg/g, 1.46 μg/mL, and 0.94 μg/g respectively. Statistical analysis of the data using a three-way ANOVA shows that the individual impacts of cardinal axis and time on distribution of pinoxaden (PXD) residue is statistically insignificant. However, the impact of depth on PXD residue was found to be highly significant as the p value <0.01. The interaction of the sampling time and depth of soil was found to have highly significant effect on the PXD residue in soil sample. Conclusions The proposed method is a milestone in the extraction of pinoxaden, a relatively new pesticide, from agricultural and environmental samples in terms of simplicity, sensitivity, and reproducibility

Preparation of microspheric Fe(III)-ion imprinted polymer for selective solid phase extraction

Abstract In this research work, an Fe(III)-IIP was prepared using methacrylic acid as monomer, divinylbenzene as cross-linker, azobisisobutyronitrile as initiator. The ion imprinted polymer was functionalized with Fe(III)8-hydroxy quinolone complex under thermal conditions by copolymerization with the monomer and the cross-linker. The prepared Fe(III)-ion imprinted polymer (IIP) and non-ion imprinted polymer (Non-IIP) were characterized with fourier transform-infrared spectroscopy, scanning electron microscopic analysis and thermal gravimetric analysis. The polymer showed a good stability to thermal analysis up to a temperature of 500 °C. The size of the polymer obtained was 1 µm, large enough to be filtered easily. At pH 2.5 more affinity was observed with ion imprinted polymer in comparison to non-ion imprinted polymer. For the kinetic study, the most linear and rhythmical relation were seen in pseudo second order. The maximum sorption capacity of Fe(III) ions on Fe(III)-IIP and non-IIP was 170 and 30.0 µmolg−1, respectively. The relative selectivity factor (αr) values of Fe(III)/Fe(II), Fe(III)/Al(III) and Fe(III)/Cr(III) were 151.0, 84.6 and 91.9, respectively. The preconcentration factor was found to be 240. The developed method was successfully applied to the determination of trace Fe in the drinking water