Analytical Methods in Environmental Chemistry Journal
Volume:3 Issue: 4, Dec 2020

In this research, Zn2(BDC)2(DABCO) metal–organic framework (MOF) as a solid phase was used for separation and preconcentration toxic nickel ions (Ni) from water samples by ultrasound assisted-dispersive-micro solid phase extraction coupled to electrothermal atomic absorption spectrometry (USA-D-μ-SPE/ET-AAS). The MOF nanostructure was characterized by field emission-scanning electron microscope (FE-SEM) and transmission electron microscopey (TEM) for presentation of morphology and size of MOF synthesis. By procedure, 25 mg of Zn2(BDC)2(DABCO) as MOF adsorbent was added to 25 mL of water samples and then, Ni ions chemically adsorbed based on dative bonding of nitrogen in DABCO (1,4-diazabicyclo [2.2. 2]octane); N2(C2H4)3) at pH=8. The adsorbent was separated from liquid phase by syringe cellulose acetate filters (SCAF, 0.2 μm) and Ni ions back extracted from MOF adsorbent before determined by ET-AAS. The maximum recovery of MOF for nickel ions as a physically and chemically adsorption was obtained 34.6% and 98.8% at pH=3 and 8, respectively. The capacity adsorption of Zn2(BDC)2(DABCO), MOF for nickel was acquired 125.7 mg g-1at pH=8. By procedure, the preconcentration factor (PF), LOD, and linear range were achieved 48.7, 0.03 μg L−1 and 0.10-2.88 μg L−1, respectively (RSD<1.26). The validation of proposed method was successfully obtained by ICP- MS analysis in real samples

The toxic effect of lead (Pb) causes to anemia and iron deficiency in human body. So, the lead determination in blood/serum samples is very important. In this study, a novel adsorbent based on sulfamethizole functionalized on nanographene oxide (C3H10N4O2S2-NGO; SM-NGO) was used for extraction of Pb(II) from human blood, serum and plasma samples inbatterymanufactories workers by syringe filter-dispersive-micro solid phase extraction procedure (SF-D-μ-SPE). By procedure, 25 mg of SM-NGO mixed with 10 mL of human blood/serum or plasma samples and aspirated by 10 mL of syringe tube. After sonication of samples for 5 min, the Pb ions adsorbed based on sulfur of SM-NGO adsorbent at pH=6 and the solid phase separated by syringe coupled to Millex-FG hydrophobic PTFE membrane (0.2 μm). Then, the lead ions were back-extracted from SM-NGO/PTFE by elution phase with 0.5 mL of nitric acid solution (0.5 M). Finally, the concentrations of Pb(II) ions were determined by atom trap flame atomic absorption spectrometry (AT-FAAS) after dilution with DW up to 1 mL. After optimization, the linear range (LR), LOD and enrichment factor (EF) for Pb ions was obtained, 10-500 μg L-1, 2.5 μg L-1 and 9.86, respectively. The validation of procedure was confirmed by electhermal atomic absorption spectrophotometer (ET-AAS) and certified reference material (NIST, CRM) in human samples

The perchloroethylene (PCE, tetrachloroethylene), as a representative of chlorinated ethylenes and volatile organic compounds (VOCs), can be easily transported and remain in the atmosphere due to its volatility and stability properties. As a result, there is a crucial need to reduce this pollution to the extent permitted by international standards. The concentration of PCE determined with Gas chromatography–mass spectrometry analyzer (GC-MS). Activated nanocarbons (ACs) doped with nitrogen functional groups were prepared using the walnut shell as a precursor to evaluate their adsorption capacity for PCE vapors. Several techniques, including scanning electron microscopy (SEM), N2 adsorption-desorption, and the Fourier transforms infrared spectrometry (FTIR), were applied to characterize the physical-chemical properties of the ACs. It is found that the PCE adsorption considerably increased on the nitrogen-doped ACs (KNCWS) due to their structural and surface charge properties. By conducting kinetic study, the pseudo-first-order model matched well with experimental data that could indicate reversible adsorption of the PCE on heteroatom doped ACs. The sips model agreed well with the equilibrium adsorption of PCE on the nitrogen-doped ACs, and the maximum adsorption capacities for PCE reached 166, 285, and 95 mg/g for KNCWS-11, KNCWS-21, and KNCWS-31, respectively. Also, the concentration of PCE were online measured based on nitrogen-doped ACs as solid-phase extraction (SPE) by the GC-MS as analytical procedure. Therefore, the nitrogen-doped ACs was good choices for the removal of PCE vapors.

The analysis of organochlorine pesticides (OCPs) residues has received an increasing attention in the last decades. Thesolid-phase microextration (SPME) is a convenient and fast analytical method, which has been widely used for the determination of volatile and semivolatile organic compounds in aqueous samples. In this study, the multiwalled carbon nanotubes/polypyrrole composite (MWCNTs-PPy) coated on steel fiber was used for extraction OCPs from water samples by the SPME technique. The effects of various parameters on the efficiency of SPME process such as extraction time, extraction temperature, ionic strength, desorption time, and desorption temperature were studied. Under optimized conditions, the detection limits for the OCPs varied between 0.051 and 0.39 pg mL-1, the inter-day and intra-day relative standard deviations for various OCPs using a single fiber were 6.5-11.5% and 3.6-11.5, respectively. The linear ranges varied between 0.001 and 1 ng mL-1. The proposed method was successfully applied to the analysis of ground water samples with the recoveries from 86 to 110%

In this work, ultrasound-assisted dispersive micro-solid phase extraction (USA-D-μSPE) technique using graphitized carbon nitride (g-C3N4) is proposed for the preconcentration of low level of lead in aqueous samples. In this method, microparticles of graphitized carbon nitride sorbent were dispersed in the samples using ultrasonic bath and Pb(II) ions were directly adsorbed on the surface of g-C3N4particles. After adsorption and desorption of lead ions from g-C3N4particles, the Pb concentration was determined by the inductively coupled plasma- optical emission spectroscopy (ICP-OES). The main advantages of this method are high speed, simplicity and cheapness. The effects of pH, sorbent amount, eluent type and time on the recovery of the analyte were investigated. Under the optimized conditions and preconcentration of 10 mL of sample, the detection limit of 1.24 μg L-1 was obtained. The results were validated by standard reference materials (NIST, SRM) and spiking of real samples by USA-D-μSPE procedure.

The contamination of coastal sediments with toxic heavy metals caused to a serious concern due to their environmental consequences. The aim of this study was to determine the concentration of heavy metals such as lead (Pb), copper (Cu), nickel(Ni) and manganese (Mn) in the sediments of the Persian Gulf coast in Kangan and Siraf ports in Bushehr province. In this regard, the sampling was performed in 10 stations with different uses in two depths of 0-5 and 5-20 cm along the coast of the Persian Gulf. The concentration of heavy metals was measured after drying, acid digestion and microwave by using flame atomic absorption spectrometry (F-AAS). Ecological risk index was used to assess the potential of environmental risk due to heavy metal pollution in the coastal sediments of the study area and the sensitivity of the biological community to toxic substances. Then statistical analysis in SPSS environment was used for analyzing the data. The results showed that the average concentrations of Mn(II), Ni(II), Cu(II) and Pb(II) was measured 121.47, 11.51, 11.59 and 5.30 in surface sediments, and 131.59, 10.81, 12.56 and 4.88 μg g-1 in deep sediments. The results of the ecological risk index with the value of less than 150, showed a low environmental risk of heavy metals detected in the region. Also, the results of multivariate statistical analyzes indicated the existence of a correlation and common origin of Cu, Ni and Mn. In general, this study led to a better understanding of the contamination of heavy metals in the region and considered it necessary to try to prevent, control and reduce the amount of pollution in the sediments of the Persian Gulf coast. All analysis validated by electrothermal atomic absorption spectrometry(ET-AAS) after dilution samples with DW

The water, wastewater and air are the main sources of aniline in environment. Aniline has a toxic effect in the human body and environment and so, must be determined by novel techniques. In this study, the activated carbon with microwave heating methods(MHM-ACNPs) were used for extraction aniline from waters by dispersive ionic liquid solid phase extraction procedure (D-IL-SPE) and compared to the activated carbon (AC). For this purpose, the mixture of acetone, ionic liquid and 30 mg of MHM-ACNPs/AC added to 100 mL of water samples at pH=8. After sonication for 10 min, the benzene ring in aniline as electron acceptor was chemically adsorbed on carboxylic groups of MHM-ACNPs aselectron donors (MHM-ACNPs-COO─......C6H5-NH2) and then, the adsorbent was collected by hydrophobic ionic liquid phase in bottom of conical centrifuging tube. Finally, the aniline was released from MHM-ACNPs in remained solution by changing pH and the concentration of aniline determined by gas chromatography–flame ionization detector (GC-FID). The working range (WR) was obtained from 2.0 to 4000 μgL-1(RSD % < 1.8). The detection limit (LOD) and preconcentration factor (PF) and linear range (LR) were achieve 0.6 μgL-1, 196.4 and 2.0─950 μgL-1, respectively. The proposed method was validated by spiking of real samples and analysis with gas chromatography mass detector (GC-MS)