Pitting corrosion of zinc in alkaline medium by thiocyanate ions

This paper describes the use of potentiodynamic anodic polarization, cyclic voltammetry and chronoamperometry techniques in order to study the pitting corrosion susceptibility of a Zn electrode in KOH solutions containing KSCN as a pitting corrosion agent. Measurements were conducted under different experimental conditions. The results demonstrated that in the absence of KSCN, the anodic voltammetric response displays two anodic peaks prior to reaching the oxygen evolution potential. The first anodic peak A₁ is related to the electroformation of Zn(OH)₂. Peak A₁ is followed by a wide passive region which extends up to the appearance of the second anodic peak A₂. The latter is assigned to the formation of ZnO₂. Addition of SCN⁻ ions to the KOH solutions stimulates the anodic dissolution through peak A₁ and breaks down the passive layer prior to peak A₂. The breakdown potential decreases with an increase in SCN⁻ concentration and temperature, but increases with an increase in KOH concentration and potential scan rate. Successive cycling leads to a progressive increase in breakdown potential. The current/time transients show that the incubation time for passivity breakdown decreases slightly with increasing applied positive potential, SCN⁻ concentration, and temperature.     

Some reactions of 4-[(2′,3′-diphenyl-6′-methoxy-5′-benzofuranyl)-methylene]- and 4-[(2′,3′-diphenyl-5′-methoxy-6′-benzofuranyl)-methylene]-2-phenyloxazolin-5-one

2,3-Diphenyl-5-formyl-6-methoxybenzofuran was reacted with hippuric acid to give 4-[(2′,3′-diphenyl-6′-methoxy-5′-benzofuranyl)methylene]-2-phenyloxazolin-5-one. The above mentioned oxazolone yielded 2,3-diphenyl-6-methoxybenzofuranylacetic acid by reaction with hydrazine hydrate, nitrous acid, benzene followed by acid hydrolysis. The reactions of the oxazolone with hydroxylamine hydrochloride and primary or secondary amines were also investigated.     

The Behavior of 3,4,5-Trimethoxybenzylidenemalononitrile Towards Alkyl Phosphites

3,4,5-Trimethoxybenzylidenemalononitrile 1 reacts with trialkyl phosphites 2a-c in the absence of solvent to give the phosphonate derivatives 4a-c . The dimeric compound 6 also was produced in the reaction with 2c . The phosphonates 8a-c were produced when compound 1 was allowed to react with dialkyl phosphites 3a-c under the same experimental conditions. A mechanism is proposed to explain the formation of compounds 4 and 6 .     

Radio-Detoxication of Olive Cake

The possibility of reducing toxic substances in olive by-products subjected as animal feed stuffs after oil extraction was investigated.

Total phenols in fresh olive fruits were 0.6%(fruit),0.7%(woody pit) and 0.31%in cakes after extraction. Irradiation of the olive cake powder at different doses (0,10,50 and 100 kGy) was done as a trial to remove the toxic substances. The results proved that irradiation decreases total phenols of olive cake from 0.31% (control) to 0.21, 0.16 and 0.08%at the doses used, respectively.

Subcutaneously injected ethanolic extract of unirradiated or irradiated (with 10 kGy) olive cake was lethal to the rats, while at 50 and 100 kGy all rats survived.

Liver and heart functions were measured in terms of activities of glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), total protein and lactic acid dehydrogenase (LDH). In addition, plasma total lipids, cholesterol, triglycerides, glucose and blood heamoglobin were measured.

Results obtained showed that the toxic substances in olive cake induced toxicosis symptoms with the experimental rats treated with the irradiated (50 kGy) samples. The toxic compounds could be destroyed at an irradiation dose level of 100 kGy without harmful effects on liver and heart functions as well as heamoglobin, carbohydrate and lipid metabolisms. After further investigations, irradiation with 100 kGy shall be recommended to be used for detoxication of olive by-products for animal feeding without deleterious side effects.     

Single‐step modified QuEChERS for determination of chlorothalonil in shallot (Allium ascalonicum) using GC‐μECD and confirmation via mass spectrometry

A single extraction method was developed for chlorothalonil in shallot using gas chromatography with an electron capture detector (GC‐μECD). Samples were extracted with single‐step modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method using ethyl acetate as an extraction solvent. Significant matrix effects were observed, and the calibration curve was constructed from the matrix. The linearity of the analytical response across the studied range of concentrations (0.01–1.00 mg/L) was excellent, obtaining a correlation coefficient (r²) of 0.996. >0.996. Recovery studies were carried out on spiked shallot blank samples, at two concentration levels (0.4 and 2.0 mg/kg) with three replicates performed at each level. Mean recoveries of 97.2–104.9% with RSDs of 1.3–2.7% were obtained. The method is demonstrated to be suitable for the determination of chlorothalonil in shallot. The dissipation rates of chlorothalonil were described using first‐order kinetics, and its half‐life was 2.8 days. Based on the dissipation pattern of the pesticide residues, the pre‐harvest residue limit (PHRL) was also calculated. Residues were confirmed via mass spectrometry. Copyright © 2012 John Wiley & Sons, Ltd.     

Various extraction methods for detection of bistrifluron residues in Asian pear using high‐performance liquid chromatography: application to dissipation patterns under open‐field conditions

The present study was carried out to develop an analytical method for the detection and quantification of bistrifluron, a benzoylphenylurea compound, in pear using high‐performance liquid chromatography with UV detection. Samples were extracted using conventional, AOAC and EN quick, easy, cheap, effective, rugged and safe ‘QuEChERS’ methods. As expected, conventional and EN‐QuEChERS methods gave higher recoveries than AOAC. In addition, interference around the analyte retention time was observed in the conventional method. Thus, the EN‐QuEChERS method was selected and validated by studying various parameters, including linearity, limit of detection, limit of quantification (LOQ), recovery and precision. Linearity was excellent, with a correlation coefficient of 0.9998. Recovery rates at three spiking levels (0.05, 0.2 and 1 mg/kg) ranged from 73.76 to 98.66%. Intra‐ and inter‐day precisions, expressed as relative standard deviations, were <6%. The LOQ of 0.05 mg/kg was considerably lower than the maximum residue limit (1 mg/kg) set by the Korean Ministry of Food and Drug Safety. The developed method was successfully applied to open‐field pear samples, in which the target analyte was slowly dissipated (55% decline) over 14 days with a half‐life of 10.19 days. Notably, the residue levels throughout the period of sample collection (14 days) were lower than the maximum residue limit, indicating that the residue was not hazardous for consumers. Copyright © 2016 John Wiley & Sons, Ltd.