Analytical Methods in Environmental Chemistry Journal

Abstract A simple in-vitro speciation of inorganic selenium (Se^IV and Se^VI) in serum blood and urine of hyperthyroidism and hypothyroidism patients based on isopropyl 2-[(isopropoxycarbothiolyl) disulfanyl] ethane thioate (IICDET) as a complexing agent were studied by ultrasound-assisted dispersive liquid-liquid bio-microextraction procedure (USA-DLLMBE).  In first stage, 100 μL (≈0.1 g) of hydrophobic ionic liquid of [C₈MIM][PF₆] mixed with IICDET ligand and 100 μL of acetone. Then, the mixture injected to 10 mL of samples at pH=4. After shacking, the Se (IV) ions were complexed by IICDET and extracted to IL at pH=4 (R-S: …Se). The IL phase was separated from sample by centrifuging and inorganic selenium (Se _IV) in remained samples was determined by electro thermal atomic absorption spectrometry (ET-AAS) after back extraction of Se (IV). As speciation, the Se (VI) reduced to Se (IV) in acidic pH (HCl, 130^OC) and the total Se(T-Se) was obtained at pH=4.  

Abstract Dispersive liquid–liquid microextraction coupled with UV–Vis spectrophotometry was applied for the determination of zirconium in aqueous samples. In this method a small amount of chloroform as the extraction solvent was dissolved in pure ethanol as the disperser solvent, then the binary solution was rapidly injected by a syringe into the water sample solution containing Zr(IV), xylenol orange and cetyltrimethylammonium bromide. The formed ion-associate was extracted into the fine chloroform droplets. The detection limit for Zr(IV) was 0.010 µg mL⁻¹. The precision of the method, evaluated as the relative standard deviation obtained by analyzing of 10 replicates, was 2.7 %. The practical applicability of the developed method was examined using natural waters and ceramic samples.

Abstract Antibiotics and pharmaceutical products cannot remove by conventional sewage treatment. In this work, an effective adsorbent Magnetic Multiwalled Carbon nanotube (MMWCNTs) was synthesized by co-precipitation of MWCNTs with Fe₃O₄ and used for removal of Amoxicillin from aqueous solutions. Response surface methodology on Central Composition Design (CCD) was applied for designing of experiments and building of models. Four factors including pH, adsorbent dose, time, and temperature were studied and used for the quadratic equation model to the prediction of optimal points.  By solvent the equation and considering the regression coefficient (R² =0.99) the optimal points obtained as follows: pH =2.98; adsorbent dosage =2.16 g; time =22 min and temperature = 37.88 ^o C. Isotherm study of adsorption showed that the adsorption of amoxicillin onto MMWCNTs follows the Langmuir model. The maximum adsorption capacity is 215 mg g^-1 obtained from Langmuir isotherm. 

Abstract In this work the effect of amoxicillin on copper and zinc (Cu and Zn) deficiency was evaluated by determining of Cu and Zn concentration in human serum and urine samples. By dispersive ionic liquid cloud point extraction procedure (DIL-CPE), 0.03 g of pure amoxicillin drug was added to mixture of 0.1 g of hydrophobic ionic liquid and 0.2 mL acetone which was injected to 2 mL of serum or urine samples which was diluted with DW up to 10 mL. The cloudy solution was shacked for 7 min and Cu and Zn ions was extracted based on sulfur group on amoxicillin ligand at pH of 7 by DIL-CPE. Then, the solution centrifuged and after back extraction with I mL of nitric acid (0.2 M), the remained solution was determined by flame atomic absorption spectrometry (F-AAS).

Abstract Antibiotics and pharmaceutical products cannot remove by conventional sewage treatment. In this work, an effective adsorbent magnetic multiwalled carbon nanotube (Fe₃O_4@MWCNTs) was synthesized by co-precipitation of MWCNTs with Fe₃O₄ and used for removal of Metronidazole from aqueous solutions. Response surface methodology on central composition design (CCD) was applied for designing of experiments and building of models for Metronidazole removal before a determination by HPLC. Four factors including pH, the adsorbent dose, time, and temperature were studied and used for the quadratic equation model to the prediction of optimal points.  By solvent the equation and considering the regression coefficient (R² =0.9997), the optimal points obtained as follows: pH =2.98; adsorbent dosage =2.16 g; time =22 min and temperature = 37.9 ^o C. The isotherm study of adsorption showed that the metronidazole adsorption on Fe₃O_4@MWCNTs follows the Langmuir model. The maximum adsorption capacity (AC) is 215 mg g^-1 obtained from Langmuir isotherm.

Abstract Molybdenum (Mo) ions enter to human body from the diet or drinking waters and have a potentially toxic effect on humans. The thiol-functionalized mesoporous silica nanoparticles (HS-MSNPs) were used for determination and speciation of Mo (II, VI) in human biological samples by dispersive ionic liquid-micro-solid phase extraction (DIL-μ-SPE) coupled to electrothermal atomic absorption spectrometry (ET-AAS). Firstly, the mixture of HS-MSNPs (15 mg), the hydrophobic ionic liquid (1-Hexyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate; [HMIM][T(PFE)PF₃]) and acetone injected into 10 mL of human blood and serum samples. After shaking for 5 min, the Mo(II) and Mo(VI) ions were extracted with the thiol group of MSNPs at pH 6 and 2, respectively, and collected through IL at the bottom of the conical tube by centrifuging. Then, the MO(II,VI) ions were back-extracted from HS-MSNPs with elent based on changing pH, and remained solutions were determined by ET-AAS after dilution with DW up to 0.5 mL, separately.

Abstract A novel method based on the synthesis of dithioglycerol immobilized on carbon nanotubes (CNTs@DTG) was used for speciation of chromium (Cr _III and Cr _VI) in human blood samples by dispersive micro solid-phase bio extraction (D-μ-SPBE). By procedure, a mixture containing acetone, 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM][PF₆]), and CNTs@DTG were injected into 5 mL of the standard sample containing 1.0 μg L^-1 of Cr _III and Cr _VI which was diluted with DW up to 10 mL at optimized pH. The Cr (VI) anions and Cr (III) cations were efficiently extracted by HS of CNTs@DTG at pH 2 and 6, respectively (HS.....Cr), and trapped into IL phase at the bottom of the conical tube. Then, Cr (III) and Cr(VI) ions were back-extracted before determined by electrothermal atomic absorption spectrometry (ETAAS). The enrichment factor (EF), linear range, and limit of detection (LOD) were obtained 9.85, 0.12-3.88 μg L^-1, and 30 ng L^-1, respectively.