فهرست مطالب mohammadreza ashar mogaddam

The proposed analytical method tries to illustrate a new approach for the extraction of some pesticides from different fruit beverages (orange, pineapple, cherry, and mango) using UiO-66 as a capable adsorbent. Further preconcentration for heightening enrichment factors of the analytes was accomplished using a dispersive liquid-liquid microextraction. The synthesized adsorbent was carefully characterized using nitrogen adsorption/desorption, X-ray diffraction, MAP, Fourier transform infrared spectrophotometry, energy dispersive X-ray, and scanning electron microscopy analyses. The performed analyses proved the successful formation of the desired compound. After the sorption of the target compounds onto UiO-66 particles by vortexing, the adsorbent was separated by centrifugation. The analyte-loaded adsorbent was treated with 1.0 mL of acetonitrile for the aim of desorption. The obtained eluate containing the desorbed pesticides was mixed with 38 µL of 1,1,1-trichloroethane and hastily injected into sodium chloride solution. After the centrifugation, an aliquot of the sedimented phase was injected into a gas chromatograph equipped with a flame ionization detector. Satisfactory figures of merit obtained in this survey consisted of high enrichment factors (215-275), acceptable extraction recoveries (43-55%), low limits of detection (1.10-2.35 µg L-1) and quantification (3.66-7.82 µg L-1), low relative standard deviations (≤ 7.8%), and wide linear ranges. Also, the proposed method benefits from the high surface area of the adsorbent and low matrix effect.

Astaxanthin is a carotenoid produced by different microalgaes, bacterias, and yeasts in fish samples. Some fishes like salmon contains astaxanthin in their muscles and it can be a proper indicator for identification of fishes. In this work, a simple and validated ultrasonic-assisted liquid-liquid extraction coupled to high performance liquid chromatography-ultraviolet detector was developed for determination of astaxanthin in fish samples in order to identify the trout from colored salmon sold in Iranian fish markets. Under the optimum conditions, analytical features of the method including limit of detection (1.46 ng/g) and quantification (5.46 ng/g), linearity (r2=0.995), precision (RSD≤5.2%), accuracy (RSD≤8%), and recovery (90%) were acceptable. The method was successfully used to determine the target analyte in several fish samples including thirty salmon produced in Iran, five salmon produced in Norway, and five trout samples. The results showed that trout samples were free of astaxanthin, while salmon samples produced in Iran have astaxanthin in the range of 179 ± 9 - 782 ± 40 ng/g. The content of astaxanthin in Norwegian salmons is much higher than salmon samples produced in Iran.

Bisphenol A is a monomer used in production of several plastic resins in food storage containers. Residue of BPA in plastics can be found in foods filled into the containers. Due to this fact that BPA is an endocrine disruptor, its dietary exposure must be estimated. In this method, the analyte was extracted using a dispersive liquid-liquid microextraction procedure from water and milk samples. For this purpose, a mixture of acetone and chloroform (142 µL) was dispersed into the water sample or aqueous phase obtained from milk after its deproteinization with trichloroacetic acid. In both samples, the obtained cloudy solutions were centrifuged and the sedimented phase analyzed by high performance liquid chromatography-ultraviolet detector. Analytical features of the method consist of limits of detection (0.44 ng mL-1 in water and 0.51 ng mL-1 in milk samples) and quantification (1.47 ng mL-1 in water and 1.72 ng mL-1 in milk samples), linearity (r2=0.992), precision (RSD≤11.1%), and accuracy (RSD≤3%) were studied under final conditions. The results showed that the obtained results are acceptable. Different milk and water samples were analyzed using the developed method and BPA was found in several samples in the ranges of 11.2-32.6 and 9.6-23.5 ng mL-1 in milk and water samples, respectively. Comparing the results with maximum residue limit established by European Commission showed that BPA content was higher than the permitted level.