Correlation between heavy metal exposure and GSTM1 polymorphism in Iranian multiple sclerosis patients.

Multiple sclerosis (MS) is an immune-mediated chronic inflammatory disease of the central nervous system. Various exposures to heavy metals can lead to toxicity and oxidative stress. While glutathione-S-transferases are known as oxidative stress-related genes and involved in metal biotransformation. The aim of the present study is to investigate the correlation of GSTM1 polymorphism in MS patients and the possible association with blood concentration of arsenic (As) and cadmium (Cd) as major heavy metal pollutants. This study included 69 relapsing-remitting multiple sclerosis patients and 74 age/gender-matched healthy subjects. The genetic profile was analyzed by PCR, and heavy metal concentrations were measured by electrothermal atomic absorption spectrometry. Our results demonstrated that patients with the GSTM1 null genotype had considerably lower age of onset. However, the frequency of the GSTM1 null genotype was not significantly different between MS and control groups. In addition, the blood As and Cd concentrations were considerably higher in MS patients in comparison with healthy individuals. Also, it revealed that the GSTM1 null genotype associated with high Cd level in MS patients. There was also a trend toward an increase in As level in MS patients. These data may point to susceptibility to cadmium toxicity especially in RR-MS patients with smoking habit. Furthermore, the M1 null genotype will help in a prognosis of MS considering the age of onset. It confirms that the long-term prognosis in MS and patient's disability are influenced by their ability to remove the toxic products and perhaps to decrease oxidative stress.

An immobilization of 2-(Aminomethyl) thiazole on multi-walled carbon nanotubes used for rapid extraction of manganese ions in hepatic patients.

A new method based on the immobilization of 2-(Aminomethyl) thiazole on the multi-walled carbon nanotubes (AMTZ@MWCNTs) was used to extract manganese (Mn) in the human blood, serum, and urine samples. First, 20 mg of AMTZ@MWCNTs, 0.2 mL of acetone, and 0.1 g of ionic liquid (IL) were completely mixed and injected into 2.0 mL human samples by a microscale syringe at pH 5.5. After shaking and centrifuging, the Mn ions were extracted and separated through the ultrasound-assisted- ionic liquid-dispersive micro solid-phase extraction (UAS-IL-D-µ-SPE) before being determined by the graphite furnace atomic absorption spectrometry (GF-AAS). According to the results, manganese in the blood of hepatic patients had higher concentrations than healthy people (Aged 25-60, 50 N). The Mn adsorption capacities for the AMTZ@MWCNTs and MWCNTs adsorbents were achieved at 192.5 mg/g and 26.3 mg/g, respectively. In the high enrichment factor (HEF), the limit of detection (LOD), linear range (LR), and mean relative standard division (RSD%) were calculated at 15 ng/L, 0.05-3.8 µg/L, and 2.34, respectively (n = 10). The methodology was validated using certified reference material (CRM) and spiking standard solutions to human samples.

Simultaneously speciation of mercury in water, human blood and food samples based on pyrrolic and pyridinic nitrogen doped porous graphene nanostructure.

A rapid and efficient method based on a novel nitrogen-doped porous graphene nanostructure (NDPG) was used for the speciation of mercury in water and human blood samples by the CV-AAS. The mixture of the NDPG, ionic liquid, and acetone was rapidly injected into the human blood, water, and food samples for mercury separation by the cloud point assisted dispersive ionic liquid-micro solid-phase extraction (CPA-DIL-µ-SPE) at pH 7.5. The UV-microwave accessory converted the organic mercury (R-Hg) to inorganic mercury, and total mercury (TM) was determined. Finally, the organic mercury was calculated by subtracting the inorganic and entire mercury contents. By optimizing, the linear range, LOD, and enrichment factor were obtained (0.01-6.80 µg/L; 0.005-3.60 µg/L), (2.6 ng/L; 1.2 ng/L) and (9.8; 20.2) for the mercury species in human blood and water/food samples, respectively (Mean of RSD < 1.9 %). The CRM samples obtained the validation of the procedure.

Rapid extraction of BTEX in water and milk samples based on functionalized multi-walled carbon nanotubes by dispersive homogenized-micro-solid phase extraction.

An advanced synthesis based on the phenylalanine (Phe) and task-specific ionic liquid (TSIL) functionalized on multi-walled carbon nanotubes (Phe/TSIL@MWCNTs), was used to extract benzene, ethylbenzene, toluene, and xylene (BTEX) from cow's milk, powdered milk, and farm water samples. The BTEX was efficiently extracted by ultrasound-assisted dispersive homogenized-micro-solid phase extraction (USA-DH-µ-SPE) between 95.1% and 103.4%. By procedure, 50 mg of Phe/TSIL@MWCNTs was added to 0.2 mL of acetone and injected into 10 mL of the samples. The upper aqueous solution was vacuumed, the vial heated to 80 °C, and the BTEX desorbed in the vial. Then, using a Hamilton syringe, 1-20 µL of gas in the headspace vial was determined by injecting it into the gas chromatography with flame ionization detection (GC-FID). The linear range, LOD, and LOQ for BTEX in milk and water samples were obtained at 0.05-500 µg L-1, 15 ng L-1, and 50 ng L-1, respectively (r = 0.9997, RSD% = 2.27).

An immobilization of aminopropyl trimethoxysilane-phenanthrene carbaldehyde on graphene oxide for toluene extraction and separation in water samples.

A new functionalized Nano graphene with aminopropyl trimethoxysilane-phenanthrene-4-carbaldehyde (NGO@APTMS-PNTCA) as a novel adsorbent was used to extract toluene from water samples by the ultrasound-assisted dispersive solid-phase microextraction procedure (USA-D-SPME). So, 50 mg of NGO@APTMS-PNTCA adsorbent was added to water samples and sonicated for 20 min. After toluene extraction, the NGO@APTMS-PNTCA adsorbent separated from the liquid phase with a Whatman membrane filter (200 nm). Then, the toluene was back-extracted from the adsorbent by 2.0 mL of the acetone/ethanol (1:1, eluent) at 25 °C. Due to the physical properties and structure of toluene, fluorobenzene was used as an internal standard. Finally, the toluene values were measured by a gas chromatography-flame ionization detector (GC-FID). In optimized conditions, the limit of detection (LOD), the working range (WR), and the enrichment factor (EF) were obtained at 2.5 µg L-1, 0.01-1.2 mg L-1, and 9.63, respectively (MRSD% = 3.38). Also, the limit of quantification (LOQ) 10 µg L-1 and extraction recovery of more than 95% was efficiently achieved for toluene. Standard additions of toluene to blank solutions had high recoveries between 95.2% and 104.5% with a relative standard deviation (RSD%) of 0.27-5.2. The absorption capacities of NGO and NGO@APTMS-PNTCA adsorbents for toluene extraction were obtained at 32.8 mg g-1 and 154.9 mg g-1, respectively. The USA-D-SPME method was validated by spiking the standard concentrations of toluene. The proposed method demonstrated relevant and suitable statistical results with high accuracy and precision for toluene extraction by a novel adsorbent synthesis.

Simultaneously speciation and determination of manganese (II) and (VII) ions in water, food, and vegetable samples based on immobilization of N-acetylcysteine on multi-walled carbon nanotubes.

A novel method based on the immobilization of N-acetylcysteine on chloro-functionalized multi-walled carbon nanotubes (MWCNTs@NAC) was used for the speciation of manganese ions [Mn (II) and Mn(VII)] in water samples. Also, the total manganese (TMn) in vegetables and food samples was determined by the AT-FAAS. By ultrasound-assisted-dispersive ionic liquid trap micro solid-phase extraction (UA-DILT-µ-SPE), the Mn (II)/Mn(VII) ions were extracted in the presence of MWCNTs@NAC for 50 mL of water samples at a pH of 6.5 and 3.0, respectively. The adsorption capacity of MWCNTs@NAC for Mn(II) and Mn(VII) ions was obtained at 146.7 mg g-1 and 138.8 mg g-1, respectively. Under the optimized conditions, the detection limits (LOD), linear range (LR), and enrichment factor (EF) for Mn(II) and Mn(VII) ions were obtained (0.12 µg L-1; 0.14 µg L-1), (0.48-36 µg L-1; 0.55-38.1 µg L-1) and (100.2; 94.5), respectively. The proposed methodology was successfully validated by the CRM samples.

Thiol modified bimodal mesoporous silica nanoparticles for removal and determination toxic vanadium from air and human biological samples in petrochemical workers.

Investigation of exposure to toxic vanadium (V) in petrochemical workers is very important for human health, and it must be removed and determined in workplace air and human biological samples. In this research, the enriched adsorbent based on the thiol modified bimodal mesoporous silica nanoparticle (HS-UVM7) was used for the extraction vanadium in human blood by the dispersive sonication ionic liquid micro solid phase extraction (DS-IL-µ-SPE) at pH of 4.5. In addition, the vanadium (V) was removed from the industrial workplace air based on HS-UVM7 adsorbent by the liquid-solid phase-gas removal (LSP-GR). In the static and dynamic system, the vanadium (V) was removed from artificial air with HS-UVM7 and compared with the polyvinyl chloride membrane (PCM, sorbent in 7300 NIOSH). The LSP-GR procedure based on HS-UVM7 had more recovery and adsorption capacity as compared to PCM. The adsorption capacity of HS-UVM7 and UVM7 adsorbents were obtained 144.1 mg g-1 and 23.3 mg g-1, respectively. In addition, the main parameters effected on extraction vanadium in blood samples and removal from air were studied and optimized by ET-AAS. The LOD, RSD%, linear range (LR) and enrichment factor (EF) was achieved 0.03 µg L-1, 3.1, 0.1-4.5 µg L-1 and 48.7, respectively for extraction of vanadium in 10 mL of blood samples by the DS-IL-MSPE procedure. The validation of the methodology was confirmed by standard addition to gas phase and using certified reference materials (CRM, NIST) or ICP-MS in human blood samples.

Rapid Speciation of Lead in Human Blood and Urine Samples Based on MWCNTs@DMP by Dispersive Ionic Liquid-Suspension-Micro-Solid Phase Extraction.

An efficient sorbent based on 2,3-dimercapto-1-propanol immobilized on multi-wall carbon nanotubes (MWCNTs@DMP) was developed for separation/speciation of organic and inorganic lead (alkyl-Pb, Pb2+) in human blood, urine, and water samples by dispersive ionic liquid-suspension-micro-solid phase extraction (DIL-S-µ-SPE). By procedure, the MWCNTs@DMP as solid phase, acetone, and ionic liquid (IL, [HMIM][PF6]) were mixed and injected to 10 mL of the liquid phase at pH = 6.5. After shaking, the Pb(II) was extracted in MWCNTs@DMP and settled down in a conical tube with IL by centrifuging (Pb2+→: SH-SiO2@CNTs). The lead (Pb2+) was back-extracted from sorbent/IL in acidic pH and measured by atom trap atomic absorption spectrometry (AT-AAS). In addition, the organic lead (R-Pb, alkyl lead) converted to Pb(II) and total lead (T-Pb) was determined in the same conditions by UV radiation in 95 °C. Under the optimal conditions, the linear range (9.5-480 µg L-1), LOD (3.2 µg L-1), and enrichment factor (10.4) were obtained (RSD < 5%). The adsorption capacity of the MWCNTs@DMP and MWCNTs was achieved as 191.6 mg g-1 and 25.8 mg g-1, respectively. The method was validated by standard reference materials (SRM 1643d, SRM 955, and SRM 2668), ET-AAS, and ICP-MS analysis in real samples. Graphical abstract.

Nanographene oxide modified phenyl methanethiol nanomagnetic composite for rapid separation of aluminum in wastewaters, foods, and vegetable samples by microwave dispersive magnetic micro solid-phase extraction.

A new method based on graphene oxide modified (4-phenyl) methanethiol nanomagnetic composite (Fe3O4@4-PhMT-GO) was used for extraction and separation of aluminum from wastewater, food, and vegetable samples in aluminum cookware by microwave dispersive magnetic micro solid-phase extraction (MDM-µ-SPE). In optimized conditions, the working range (WR), the linear range (LR), the limit of detection (LOD), and enrichment factor (EF) were obtained 5-5200 µg L-1, 5-1600 µg L-1, 1.5 µg L-1, and 48.8, respectively (RSD% = 2.5). By MDM-µ-SPE procedure, the aluminum concentrations in baking rice and spinach with aluminum cookware were obtained 97.43 ± 2.57 mg g-1 and 131.64 ± 5.18 mg g-1, respectively which was analyzed by atom trap flame atomic absorption spectrometer (AT-FAAS). The results showed, the aluminum concentrations in cooked foods with Teflon cookware were less than aluminum cookware. The methodology was validated by standard reference materials (SRM) and inductively coupled plasma mass spectrometry analysis (ICP-MS).

Speciation of cadmium in human blood samples based on Fe3O4-supported naphthalene-1-thiol- functionalized graphene oxide nanocomposite by ultrasound-assisted dispersive magnetic micro solid phase extraction.

Cadmium (Cd) has toxic effect in human body and exists as the inorganic (Cd2+) and organic (R-Cd) forms in human biological matrix. Due to cadmium toxicity in various forms, the speciation of cadmium in human blood samples is very important. In this study, the Fe3O4-supported naphthalene-1-thiol- functionalized graphene oxide (Fe3O4@NpSH-GO, NMNT-GO) as a novel nanomagnetic composite was used for cadmium speciation in blood samples by ultrasound-assisted dispersive magnetic micro solid phase extraction (USA-DM-µ-SPE). By procedure, 20 mg of the NMNT-GO was used for extraction of Cd(II) from 1 mL of human blood samples at pH = 6.0, before determined by electrothermal atomic absorption spectrometry (ET-AAS). The total cadmium (T-Cd) was obtained by converting organic (R-Cd) to inorganic form (Cd2+), before adjusting pH and continuing with USA-DM- µ-SPE procedure. The organic cadmium was simply calculated by subtracting total cadmium from inorganic cadmium content. In optimized conditions, the linear range (peak area), limit of detection (LOD) and the preconcentration factor were obtained 30-1520 ng L-1, 10 ng L-1 and 4.88 in human blood samples, respectively (RSD: 1.1 %). The adsorption capacities of the Fe3O4@NpSH-GO and the GO were achieved 185.3 mg g-1 and 33.7 mg g-1 for inorganic cadmium, respectively. The results were validated by certified reference materials (CRM, NIST) and inductively coupled plasma mass spectrometry (ICP-MS) in human blood samples.

A novel method based on functionalized bimodal mesoporous silica nanoparticles for efficient removal of lead aerosols pollution from air by solid-liquid gas-phase extraction.

In this study, the enrichment and novel sorbent based on functionalized bimodal mesoporous silica nanoparticles (HS-UVM7 and NH2-UVM7) was used for removal of lead aerosols pollution from air by solid liquid gas phase extraction method (SLGPE). In bench scale set up, the lead aerosols [(Pb (NO3)2, PbO] was generated by dispersive aerosols generator system (DAGS) and removed from air by reaction loop (RL) / impinger trap (IT) in a liquid phase which was mixed with nano adsorbent in optimized pH. The effect of parameters such as, flow rate, volume of liquid phase, time stirring, temperature, concentration, pH and amount of sorbent (mg) were studied and evaluated by flame atomic absorption spectrometry (FAAS). In optimized conditions, the adsorption capacity of HS-UVM7 and NH2-UVM7 for Pb(NO3)2 aerosols was obtained 255.6 mg g-1 and 177.6 mg g-1, respectively which was more than UVM7. The lead oxides aerosols (PbO) were extracted only by HS-UVM7 at acidic pH with the adsorption capacity of 271.2 mg g-1. The characterization of SEM, XRD, TEM, and FTIR showed that the HS-UVM7 has beneficial surfaces for removal of (Pb (NO3)2 and PbO aerosols from the air by SLGPE method at pH = 5. The method validation was confirmed by standard addition and NIOSH method. Graphical abstract.

Neuropsychological effects of long-term occupational exposure to mercury among chloralkali workers.

BACKGROUND: Mercury is one of the most well-known toxic metals for humans. Chloralkali workers are exposed to mercury vapours extensively, which may be associated with neurotoxicity. OBJECTIVE: The aim of this study was to determine the associations between mercury concentration in blood and air samples, and mercury's neuropsychological effects among chloralkali workers. METHODS: This study was conducted on 50 chloralkali workers as the exposed group and 50 non-industrial office workers as the unexposed group. All subjects were assessed using the Hamilton Depression Rating Scale, Piper Chronic Fatigue Scale and Essential Tremor Rating Scale. Mercury concentration was measured in blood and air samples using cold vapour atomic absorption spectrometry. RESULTS: There was significantly more severe fatigue, depression and tremor in the exposed group compared with the unexposed group. The mean concentration of blood mercury in the exposed group was 22.59±12.5µgL-1 which was significantly higher than the unexposed group (1.28±1.05µg L-1). Based on multiple linear regression, shift work, smoking, fatigue, depression and tremor were predictor variables for blood mercury concentration. CONCLUSIONS: This study indicated that this sample of chloralkali workers suffered from neuropsychological problems such as fatigue, depression and tremor, which is probably related to mercury exposure.

Is There Any Relevance Between Serum Heavy Metal Concentration and BBB Leakage in Multiple Sclerosis Patients?

Sharp increase in multiple sclerosis (MS) incidence rate has been observed in Iranian people. In addition, it has been suggested that increased S100B level may be useful as an indicative factor of blood-brain barrier disruption. The propose of this study was to measuring blood arsenic, lead, and cadmium concentration and serum S100B concentration in a group of healthy and multiple sclerosis patients in Tehran as the most polluted city in Iran. All subjects were interviewed regarding age, medical history, possible chemical exposure, acute or chronic diseases, smoking, and dietary habits. Blood heavy metal level was measured by an atomic absorption spectrometer (Varian model 220-Z) conjugated with a graphite furnace atomizer (GTA-110). Also, a serum S100B protein concentration was determined using a commercial ELISA kit. It was observed that all male subjects had higher blood metal level in comparison with healthy controls. Also, MS patients had higher arsenic and cadmium blood concentration in comparison with healthy individuals. Regarding the S100B concentration, it was observed that it had a significant relationship with smoking habit (P value = 0.0001). In addition, arsenic had a greater correlation (63%) with increased serum S100B biomarker level among other elements. BBB leakage was higher in multiple sclerosis than in healthy subjects due to increased S100B release. In addition with regard to the heavy metal exposure especially arsenic and cadmium, these are associated with an increased BBB disruption and it is possible to play a crucial role as a developing agent of multiple sclerosis.

A novel biostructure sorbent based on CysSB/MetSB@MWCNTs for separation of nickel and cobalt in biological samples by ultrasound assisted-dispersive ionic liquid-suspension solid phase micro extraction.

An efficient method based on CysSB/MetSB@MWCNTs as a novel bio structure material was used for determination/separation of nickel and cobalt (Ni and Co) in human samples by ultrasound assisted-dispersive ionic liquid-suspension solid phase micro extraction (USA-DIL-SSPME). In this procedure, CysSB/MetSB@MWCNTs suspended in 1-butyl-2,3-dimethylimidazolium hexafluorophosphate ([BDMIM][PF6]) and mixture dispersed to 10 mL of blood samples at optimized pH by injecting. Then, the Co/Ni (II) was extracted with CysSB/MetSB@MWCNTs without any ligands and settled down in conical tube by IL [Ni/Co→:SMWCNTs]. After back extraction of ions from remaining solution, the concentration of Co/Ni was determined by electro thermal atomic absorption spectrometry (ET-AAS). By optimizing, the linear range, detection limit and enrichment factor of CysSB @MWCNTs were obtained (0.1-3.4 µg L-1; 0.08-3.2 µg L-1), (0.028 µg L-1; 0.022 µg L-1) and (50.2; 48.7) for Ni and Co ions in human biological samples, respectively (RSD<5%). The adsorption capacity of CysSB@MWCNTs for Ni and Co ions was 226.7 mg g-1 and 193.3 mg g-1, respectively which was higher than MetSB@MWCNTs. The standard reference materials (NIST, SRM) and ICP-MS were used for validation of methodology.

A lead analysis based on amine functionalized bimodal mesoporous silica nanoparticles in human biological samples by ultrasound assisted-ionic liquid trap-micro solid phase extraction.

A simple and applied method based on ultrasound assisted-Ionic liquid trap-micro solid phase extraction (USA-ILT-µSPE) was demonstrated for preconcentration/separation of lead (Pb) in human blood and urine samples. By proposed method, the amine-functionalized bimodal mesoporous silica nanoparticles (NH2-UVM7) as solid phase sorbent was used for lead analysis in human biological samples at pH ≈ 7.0. After shaking/centrifuging of sample, the Pb (II) was extracted with NH2-UVM7 without any chelating agents, trapped in ionic liquid phase and settled down in conical centrifuge tube as a residual solution [Pb→:NH2-UVM7]. Finally, the lead ions was back extracted from residual solution and determined by atom trap flame atomic absorption spectrometry (AT-FAAS). Under the optimal conditions, the linear range (LR), limit of detection (LOD) and preconcentration factor (PF) were obtained (10-950 µg L-1; 2.0-210 µg L-1), (2.8 µg L-1; 0.6 µg L-1) and (19.8; 99.7) for human blood and urine samples, respectively (% RSD < 1, intra-day). The reusability and adsorption capacity of the sorbent were also obtained 24 and 213.8 mg g-1, respectively. Validation of methodology was confirmed by certified reference materials (NIST, CRM).

Identifying occupational and nonoccupational exposure to mercury in dental personnel.

The objective of this study was to investigate the occupational and nonoccupational exposure to mercury (Hg) vapor in dental personnel by examining the relationships between blood mercury, urine mercury, and their ratio with air mercury. The method was performed on 50 occupational exposed and 50 unexposed controls (25 men and 25 women). The mercury concentrations in air and human biological samples were determined based on the National Institute for Occupational Safety and Health (NIOSH) method and standard method (SM) by a new mode of liquid-phase microextraction, respectively. The mean mercury concentrations in urine (µg Hg0/g creatinine) and blood were significantly higher than control group, respectively (19.41 ± 5.18 vs 2.15 ± 0.07 µg/g and 16.40 ± 4.97 vs 2.50 ± 0.02 µg/L) (p <.001). The relationships between mercury concentration in blood/urine ratio (r = .380) with dental office air are new indicators for assessing occupational exposure in dental personnel.

Stirring-controlled solidified floating solid-liquid drop microextraction as a new solid phase-enhanced liquid-phase microextraction method by exploiting magnetic carbon nanotube-nickel hybrid.

A specific technique is introduced to overcome limitations of classical solidification of floating organic drop microextraction, such as tedious and time-consuming centrifuge step and using disperser solvent, by facile and efficient participation of solid and liquid phases. In this proposed method of stirring-controlled solidified floating solid-liquid drop microextraction (SC-SF-SLDME), magnetic carbon nanotube-nickel hybrid (MNi-CNT) as a solid part of the extractors are dispersed ultrasonically in sample solution, and the procedure followed by dispersion of liquid phase (1-undecanol) through high-rate stirring and easily recollection of MNi-CNT in organic solvent droplets through hydrophobic force. With the reduction in speed of stirring, one solid-liquid drop is formed on top of the solution. MNi-CNT acts as both extractor and the coalescence helper between organic droplets for a facile recollection. MNi-CNT was prepared by spray pyrolysis of nickel oleate/toluene mixture at 1000 °C. Four tyrosine kinase inhibitors were selected as model analytes and the effecting parameters were investigated. The results confirmed that magnetic nanoadsorbent has an important role in the procedure and complete collection of dispersed solvent is not achieved in the absence of the solid phase. Also, short extraction time exhibited success of the proposed method and effect of dispersed solid/liquid phases. The limits of quantification (LOQs) for imatinib, sunitinib, erlotinib, and nilotinib were determined to be as low as 0.7, 1.7, 0.6, and 1.0 µg L-1, respectively. The intra-day precisions (RSDs) were lower than 4.5%. Method performance was investigated by determination of mentioned tyrosine kinase inhibitors (TKIs) in human serum and cerebrospinal fluid samples with good recoveries in the range of 93-98%.

Chromium speciation in human blood samples based on acetyl cysteine by dispersive liquid-liquid biomicroextraction and in-vitro evaluation of acetyl cysteine/cysteine for decreasing of hexavalent chromium concentration.

A rapid and efficient method based on ionic liquid dispersive liquid-liquid biomicroextraction (IL-DLLBME) was used for speciation and preconcentration of Chromium (III, VI) in human blood samples before determination by electro-thermal atomic absorption spectrometer (ET-AAS). In this method, 1-hexyl-3-methylimidazolium hexafluorophosphate as a ionic liquid was dissolved in acetone as a dispersant solvent and then the binary solution was rapidly injected by a syringe into the blood samples containing Cr(III), which have already complexed by acetyl cysteine (NAC) at optimized pH. Under the optimal conditions, the linear range (LR), limit of detection (LOD) and preconcentration factor (PF) were obtained 0.03-4.4 µg L(-1), 0.005 µg L(-1) and 10 respectively (RSD <5%). In vitro study show us, the cysteine (Cys) as a prodrug of NAC can decrease the concentration of Cr(VI) in blood samples and human body. Validation of methodology was confirmed by standard reference material (SRM).

Relations of biomarkers of manganese exposure and neuropsychological effects among welders and ferroalloy smelters.

The objective of present study was to assess relationship between biomarkers of Manganese (Mn) and neuropsychological effects. The study was carried out on 27 welders and 31 ferroalloy smelters as Mn-exposed groups and 30 office workers as unexposed controls. Air Mn concentrations were determined according to NIOSH method 7300. The biological samples were prepared using microwave assisted acid digestion and all samples were analyzed by graphite furnace- atomic absorption spectroscopy (GF-AAS) in order to determine manganese. Questionnaire 16 (Q16) and Cambridge Neuropsychological Test Automated Battery (CANTAB) were used to evaluate the neuropsychological effects. The mean concentrations of air Mn for the welder and ferroalloy smelter groups were 0.023 ± 0.012 mg/m(3) and 0.008 ± 0.005 mg/m(3), respectively. Manganese concentrations in blood, urine, and toenail samples of exposed workers ranged between 1.80-32.60 (µg/l), 1.00-42.50 (µg/l), and 0.10-6.08 (µg/g), respectively. Mean Mn concentrations in all biological samples of cases were significantly higher than unexposed controls (p<0.05). A moderate relationship was observed between biomarkers of Mn exposure, air Mn, Q16 as well as some neurocognitive outcome measures. The present study shows that blood Mn, urine Mn and toenail Mn could be used to distinguish Mn-exposed workers from unexposed population at the group level.

Innovative separation and preconcentration technique of coagulating homogenous dispersive micro solid phase extraction exploiting graphene oxide nanosheets.

A uniquely novel, fast, and facile technique is introduced for the first time in which a scant amount of graphene oxide (GO), without modification, has been utilized in dispersive mode of solid phase extraction (SPE) for an efficient yet simple separation. The proposed method of coagulating homogenous dispersive micro solid phase extraction (CHD-µSPE) is based on coagulation of homogeneous GO solution with the aid of polyetheneimine (PEI). CHD-µSPE use full adsorption capacity of GO because in this method was used GO solution obtained from synthesis process without drying step and stacking nanosheets. In optimized condition, 30 µL GO solution (7 mg mL(-1)), obtained in synthesis process, was injected into 1.5 mL the sample solution followed by immediate injection of 53 µL PEI solution (1 mg mL(-1)). After inserting PEI, GO sheets aggregate and can be readily separated by centrifugation. PEI not only cause aggregation of GO, but also form three-dimensional network of GO with easy handling in following separation steps. Lead, cadmium, and chromium were selected as model analytes and the effecting parameters including the amount of GO, concentration of PEI, sample pH, extraction time, and type of desorption solvent were investigated and optimized. The results indicate that the proposed CHD-µSPE method can be successfully applied GO in dispersive mode of SPE without effecting on good capability adsorption of GO. The novel method was applied in determination of lead, cadmium, and chromium in water, human saliva, and urine samples by electrothermal atomic absorption spectrometry. The detection limits are as low as 0.035, 0.005, and 0.012 µg L(-1) for Pb, Cd, and Cr respectively. The intra-day precisions (RSDs) were lower than 3.8%. CHD-µSPE method showed a good linear ranges of 0.24-15.6, 0.015-0.95 and 0.039-2.33 µg L(-1) for Pb, Cd and Cr respectively. Method performance was investigated by determination of mentioned metal ions in river water, human urine and saliva sample with good recoveries in range of 94.2-103.0%. The accuracy of the method was underpinned by correct analysis of a standard reference material (SRM: 2668 level I, Urine).