Fast and efficient removal of mercury from water samples using magnetic iron oxide nanoparticles modified with 2-mercaptobenzothiazole.

Mercury in the lowest levels of concentrations is dangerous for human health due to its bioaccumulation in body and toxicity. This investigation shows the effective removal of mercury (II) ions from contaminated surface waters by modified magnetic iron oxide nanoparticles (M-MIONPs) with 2-mercaptobenzothiazole as an efficient adsorbent. The proposed method is fast, simple, cheap, effective and safe for treatment of mercury polluted waters. Preparation of adsorbent is easy and removal time is short. Non-modified magnetic iron oxide nanoparticles (MIONPs) can adsorb up to 43.47% of 50 ngmL(-1) of Hg (II) ions from polluted water, but modified magnetic ironoxide nanoparticles (M-MIONPs) improved the efficiency up to 98.6% for the same concentration. The required time for complete removal of mercury ions was 4 min. Variation of pH and high electrolyte concentration (NaCl) of the solution do not have considerable effect on the mercury removal efficiency. Loading capacity of adsorbent for Hg ions is obtained to be 590 µgg(-1).

Square wave voltammetric determination of methyl parathion using ZrO2-nanoparticles modified carbon paste electrode.

A carbon paste electrode is modified with ZrO(2)-nanoparticles and its application for square wave voltammetric (SWV) detection of methyl parathion, MP (organophosphate pesticide) is reported. The nano-ZrO(2) shows a strong affinity toward the phosphate group on methyl parathion molecules, which provides sensitivity and selectivity of the modified carbon paste electrode. Instrumental and chemical parameters influencing the voltammetric response are optimized for MP determination. Under optimum experimental conditions the peak current is linear to MP concentration over the range of 5.0-3000.0 ng mL(-1) with a correlation coefficient of 0.9992. The limit of detection (LOD) and limit of quantification (LOQ) for MP based on three and ten times the standard deviation of the blank (3S(b), 10S(b)) were 2.0 and 5.7 ng mL(-1) (n=20) for MP, respectively. The recovery values from quality control (QC) samples of water solutions containing low, middle and high concentrations of MP (50, 100 and 800 ng mL(-1)) were 98.0+/-2.3%, 92.5+/-4.9% and 97.6+/-2.8%, respectively. The electrode is successfully applied for the determination of MP in different water samples.

Solid phase extraction-spectrophotometric determination of fluoride in water samples using magnetic iron oxide nanoparticles.

A new, sensitive, fast and simple method using magnetic iron oxide nanoparticles (MIONs), as an adsorbent has been developed for extraction, preconcentration and determination of traces of fluoride ions. The determination method is based on the discoloration of Fe(III)-SCN complex with extracted fluoride ions which was subsequently monitored spectrophotometrically at lambda(max)=458 nm. Various parameters affecting the adsorption of fluoride by the MIONs have been investigated, such as pH of the solution, type, volume and concentration of desorbing reagent, amount of adsorbent and interference effects. A linear response for the determination of fluoride was achieved in the concentration range of 0.040-1.250 microg mL(-1). The limit of detection (LOD) and limit of quantification (LOQ) for fluoride based on 3 times and 10 times the standard deviation of the blank (3S(b), 10S(b)) were 0.015 and 0.042 microg mL(-1) (n=20) for fluoride ion, respectively. A preconcentration factor of 50 was achieved in this method. The proposed procedure has been applied for determination of fluoride concentration in various water samples. The results obtained from this method were successfully compared with those provided by standard SPADNS method.

Fast removal and recovery of amaranth by modified iron oxide magnetic nanoparticles.

The adsorption and removal of amaranth (AM) from an aqueous solution by iron oxide nanoparticles (IONPs) coated with cetyltrimethylammonium bromide (CTAB) as adsorbent was reported. The novel magnetic separation was quite efficient for the adsorption and desorption of AM. In an aqueous solution of AM at 25 degrees C, the adsorption data could be fitted by the Langmuir equation with a maximum adsorption amount of 1.05 mg mg(-1) and a Langmuir adsorption equilibrium constant of 0.90 Lmg(-1). The effect of temperature, pH of aqueous medium, electrolyte concentration, composition of desorbent solvent and interfering ions on the recovery process were also investigated. Methanol was used for desorption of adsorbed AM. Due to the absence of internal diffusion resistance both adsorption and desorption of AM were fast and could be completed within 5 min. The results indicated that the CTAB-coated IONPs could be employed in the removal of the anionic dye from wastewater. The AM was removed successfully in spiked samples of Karoon River water.

Solid phase extraction of mercury on sulfur loaded with N-(2-chloro benzoyl)-N'-phenylthiourea as a new adsorbent and determination by cold vapor atomic absorption spectrometry.

This paper reports sulfur powder loaded with N-(2-chloro benzoyl)-N'-phenylthiourea as a new solid phase extractor for determination of ultra trace amounts of mercury. The mercury ions were retained on a mini-column filled with the solid phase at a flow rate of 16 mL min(-1). The retained Hg(II) ions were eluted with 3 mol L(-1) solution of HCl and measured by cold vapor atomic absorption spectrometry (CV-AAS). The mercury vapors were generated by a homemade Reaction Cell-Gas Liquid Separator (RC-GLS). The effect of different variables such as pH, sample flow rate, amounts of ligand loaded on sulfur and SnCl2 concentration was investigated. Calibration curve was linear in the range of 0.02-1.20 microg L(-1) with r=0.9991 (n=8). The limit of detection (LOD) based on three times the standard deviation of the blank was 0.012 and 0.003 microg L(-1) when 250 and 1000 mL sample volumes were used, respectively. The relative standard deviation (R.S.D.) for determination of 0.04 and 1.00 microg L(-1) of Hg(II) was 3.9 and 1.2% (n=8), respectively. The method was successfully applied to determine Hg(II) in water and marine samples.

Solid phase extraction of lead and cadmium using solid sulfur as a new metal extractor prior to determination by flame atomic absorption spectrometry.

A new method using a mini-column packed with sulfur as a new solid phase extractor has been developed for simultaneous preconcentration of lead and cadmium in water samples prior to flame atomic absorption spectrometric determinations. The effects of various parameters such as pH, flow rate of sample and eluent, type and concentration of eluent, sample volume, amount of adsorbent and interfering ions have been studied. The calibration graph was linear in the range of 10-300 and 1-20 ng mL(-1) for lead and cadmium, respectively. The limit of detection based on three times the standard deviation of the blank (3S(b)) was 3.2 and 0.2 ng mL(-1) (n=10) for lead and cadmium, respectively. A preconcentration factor of 250 was achieved in this method. The proposed procedure was applied to the determination of metal ions in tap, river and wastewater samples.

Determination of the level of contamination in Khuzestan coastal waters (Northern Persian Gulf) by using an ecological risk index.

The aims of the present study were to investigate the metal contents of sediments of several creeks that discharged into coastal waters using the Risk index. This study was carried out in eight creeks in Mahshahr coastal waters in the Northwest of Persian Gulf from October 2005 to November 2006. Superficial sediments were collected seasonally by Peterson grab, and the concentrations of heavy metals were measured by using a voltammetric polarographic method. The range and the mean concentrations obtained in ppm were 15.03-35.16 (27.01) for Cu, 65.57-171.41 (102.67) for Ni, 4.63-20.06 (13.22) for Co, 0.093-0.78 (0.22) for Hg, 65.07-379 (113.70) for Zn, 0.27-1.00 (0.56) for Cd and 7.09-29.72 (14.66) for Pb. To evaluate the levels of sediment contamination, the background values of the different heavy metals were calculated, and the contamination factor for each metal and the degree of contamination for each creek were determined as well. The results show that some elements such as Hg, Zn, and Ni are at risk level, and all of the studied creeks are classified as undergoing a moderate degree of pollution except for Ghannam that showed a considerable degree of contamination. According to the Risk index values, based on sedimentological toxic factors (S(t)) of each metal and the BIO Production Index (BPI) in the studied area, the creeks were classified as considerable and with a very high level of ecological risk.

Modified iron oxide nanoparticles as solid phase extractor for spectrophotometeric determination and separation of basic fuchsin.

This study presents a novel separation, preconcentration and determination of basic fuchsin (BF) in an aqueous solution by sodium dodecyl sulfate (SDS)-bounded iron oxide nanoparticles (S-IONPs). It is shown that the novel magnetic nano-adsorbent is quite efficient for the adsorption and desorption of BF at 25 degrees C. Different parameters such as pH, temperature, ionic strength and composition of desorbent solvent were optimized. The effect of some co-existing ions on the determination was investigated. The nanoparticles were analyzed by transmission electron microscopy (TEM) and the sizes of S-IONPs were in the range of 20-100 nm. The method showed good linearity for the determination of BF in the range of 10-300 ng mL(-1) with a regression coefficient of 0.9989. The limit of detection (LOD) (signal-to-noise ratio of 3:1) was 0.0073 microg L(-1) and the relative standard deviation (RSD) for 0.03 microg mL(-1) and 0.2 microg mL(-1) of BF were 4.53% and 4.73%, respectively. The BF was determined successfully in spiked samples of Karoon River water.

Simultaneous square wave voltammetric determination of 2-mercaptobenzothiazole and 2-mercaptobenzoxazole by partial least squares method in water samples.

A rapid sensitive and versatile method for simultaneous determination of 2-mercaptobenzothiazole (MBT) and 2-mercaptobezoxazole (MBO) based on the square wave voltammetric (SWV) using mercury drop electrode (SMDE) has been presented. A three-electrode system containing SMDE working electrode, Pt auxiliary electrode and Ag/AgCl reference electrode was used throughout. The linear calibration graphs are in the concentration range of 7-40 microg mL(-1) and the equations are: (Deltai)=1.372CMBT-9.112 (r=0.9982) and (Deltai)=0.246CMBO-1.736 (r=0.9985) for MBT and MBO, respectively. Partial least squares regression (PLS) was applied to resolve the seriously overlapped voltammograms without any pre-separation step. The five level partial factorial design was used as calibration design method and the cross-validation method was used to select the number of significant factor for PLS model building. Five significant PLS components are used for MBT and MBO. A set of synthetic sample mixtures were used to validate the propose method. The root-mean-square errors of predictions (RMSEPs) and percent of relative prediction errors (RPEs) are 0.841 and 0.777 microg mL(-1) and +/-3.58 and +/-3.74% for MBT and MBO, respectively. The developed method was then applied to the analysis of these two compounds in different water samples with satisfactory results.

Solvent extraction-spectrophotometric determination of trace amounts of ammonium, barium and potassium in a mixture by dicyclohexyl-18-crown-6 and orange II.

A simple and sensitive extraction-spectrophotometric method for the determination of ammonium, barium and potassium in a mixture solution is reported. The DC18C6-ammonium-Orange II (DC18C6-NH(4)-OR II), DC18C6-Barium-Orange II (DC18C6-Ba-(OR II)(2)) and DC18C6-Potassium-Orange II (DC18C6-K-OR II) ternary complexes are quantitatively extracted into dichloromethane and their absorbances are measured at 483 nm. Linear calibration graphs were obtained over the concentration ranges of 0.05-3.00, 0.05-2.00 and 0.05-6.00 mug ml(-1) for ammonium, barium and potassium, respectively. The relative standard deviations for 1.0 mug ml(-1) of ammonium, barium and potassium are, respectively, 1.1, 1.6 and 2.50%. The limit of detection, LOD, for these three ions is reported to be 0.02, 0.01 and 0.02 mug ml(-1), respectively. The interfering effect of a large number of diverse ions on the determination of these three ions was studied. The method was applied to the Karon river raw water contaminated with industrial and house sewages. The results showed high potential of the recommended method for the determination of NH(4)(+), Ba(2+) and K(+) in water samples.

Determination of isosorbide dinitrate in arterial plasma, synthetic serum and pharmaceutical formulations by linear sweep voltammetry on a gold electrode.

Isosorbide dinitrate (ISDN) is reduced voltammetrically at gold working electrode surface in aqueous sodium sulfite solution and produces a voltammogram with its peak current proportional to the concentration of ISDN in the range of 1.3-2340 mug ml(-1). Sodium sulfite is used as supporting electrolyte and oxygen removing agent and, therefore, no nitrogen gas purging for elimination of soluble oxygen in, the sample solution is required. The limit of detection (LOD) of the method is 0.0838 mug ml(-1) and the relative standard deviation (R.S.D.) of 24 replicate determination of 52 mug ml(-1) of ISDN is 3.60%. The method is used for quantitative analysis of ISDN in arterial plasma, synthetic serum and pharmaceutical dosage form. The results are compared with those obtained from GC determination method. The method is sensitive and requires little sample preparation in a wide concentration range.

Spectrofluorometric study of thallium (I) complexes with several macrocyclic ligands in methanol solution.

The fluorescent signal of T1(+) was employed as a sensitive probe to study the complexation reactions between this cation and several macrocyclic ligands in methanol solution at 20 degrees C. The stability constants of the resulting 1:1 complexes were determined and found to vary in the order C222 > C221 > 18C6 > DC18C6 > DB30C10 > DB18C6 > 15C5 > DA18C6 > B15C5 > DA15C5. The influence of a number of members in the macrocycle the nature of substituents on the polyether ring and of the dimensionality of the ligands on the stability and selectivity of the complexes is discussed.