فهرست مطالب mahmoud nassiri

In this study, a sensitive and economical method is suggested for the rapid determination of formaldehyde in seawater samples. This method is based on the reaction of formaldehyde with 5, 5-di methyl-1, 3-cyclohexane dion (dimedone) in the presence of ammonium acetate. After the reaction of derivative, a mixture of 900 µL of ethanol as a dispersive solvent and 100 µL of chloroform as an extraction solvent was rapidly injected into a water sample containing formaldehyde. Their concentrations were determined spectrophotometrically in micro-cuvettes at 395 nm. Under the optimum conditions, the calibration graph was linear in the range of (0.1-100) µg/L with the detection limit of 0.02 µg/L and limit of quantification of 0.07 µg/L for formaldehyde. Parameters affecting extraction efficiency including pH, type and volume of extraction and disperser solvents, and amount of dimedone, were investigated and optimized. Under the optimum conditions, the linearity of the technique was in the range of 0.1-100.0 µg. L-1 with a detection limit of 0.02 µg. L-1 for the same compound. The relative recoveries of formaldehyde from seawater samples at spiking levels of 10 µg. L-1 were between 97.0-99.4%. The proposed method was successfully applied for the determination of formaldehyde in seawater of Chabahar Bay.

A simple, fast and effective pre-concentration method for the determination of Cu (copper) and Ni (nickel) was developed using a Surfactant Assisted Dispersive Liquid-Liquid Microextraction (SA-DLLME) coupled by UV-Vis spectrophotometry in marine brown algae. The complexing agent was 1- (2- pyridylazo) – 2 - naphthol (PAN).The effects of various experimental parameters in the extraction step including type and volume of extraction solvent, type and amount of surfactant, ionic strength, extraction time, pH, amount of ligand, and centrifugation time and rate were investigated. Under optimal experimental conditions, good linearity was observed in the range of 0.1-100.0 µg/Lfor analytes by limits of detection of 0.031 and 0.033 µg/Lfor Ni and Cu, respectively. The proposed procedure was used for the analysis of Ni and Cu in marine brown algae. Good recoveries for spiked samples in the range of 100-118 % were obtained. Using this technique, metals content in algae from Chabahar Bay (Southeast Iran) were detected in the range of 12.80- 39.46 µg/L

Environmental pollution imposes serious hazards and problems to the living organisms. This study aimed to determine the concentration and seasonal alteration of di-(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) in the surface water of Chabahar Bay. Four replicated water samples were taken from the surface layers of seven stations in Chabahar Bay and prepared by dispersive liquid–liquid microextraction (DLLME) method, before being injected into the Gas Chromatography with flame ionization detector. In this method, 0.5 ml of methanol (as diffusion solvent) and 20 µl of carbon tetrachloride (as extraction solvent) were injected quickly into the sea water samples, and after extraction, the deposited phase was taken by a Hamilton syringe and injected into the GC equipment for measurement. Under the optimum extraction and experimental conditions, the method yields a linear calibration curve in the concentration range from 10 to 600 µg/L for target analytes. The enrichment factors for DEHP and DnBP were 775 and 790, the correlation factor 0.997 and 0.997, the limits of detection were 0.04 and 1.78 µg/L and the relative standard deviations of DEHP and DnBP were 0.0036 and 0.058, respectively.The results revealed that the concentration of DEHP and DnBP differ considerably at different stations. Significant differences were also observed between the concentration of DEHP and DnBP at various stations (P ≤ 0.05).

In this paper, a simple dispersive liquid-liquid microextraction for the extraction and pre-concentration of formaldehyde in seawater samples followed with spectrophotometric is proposed. Formaldehyde was derivatized in situ with acetyl acetone in the presence of ammonium acetate in a single step. Then it was collected into a mixture of ethanol (disperser solvent) and chloroform (extracting solvent). Experimental parameters which have an influence on the extraction, including type and volume of extracting and disperser solvent, pH of sample solution, the concentration of acetyl acetone and ammonium acetate, reaction time and temperature were evaluated and optimized. Under optimal experimental conditions, good linearity was observedin the range of 1-500 µg/Lfor the analyte with a limit of detection of 0.29 µg/L. The proposed method was applied to the analysis of real seawater samples. For spiked samples, good recoveries in the range of 97.7-101.5% were obtained. The relative standard deviations were below 2.1%. Using this method, formaldehyde content in seawater from several locations in Chabahar Bay (southeast Iran) were determined in the range of 1.4 to 4.8 µg/L.