Use of silica gel chemically modified with zirconium phosphate for preconcentration and determination of lead and copper by flame atomic absorption spectrometry

Zirconium Nanoparticles Based Vortex Assisted Ligandless Dispersive Solid Phase Extraction for Trace Determination of Lead in Domestic Wastewater using Flame Atomic Absorption Spectrophotometry

In this paper, a sensitive and simple zirconium nanoparticles (Zr-NPs) based vortex assisted ligandless dispersive solid phase extraction (VA-LDSPE) method was developed for the preconcentration of lead from wastewater samples for the determination by slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS). Zr-NPs were synthesized using zirconium (IV) chloride salt as a starting material through a simple reduction process with sodium borohydride, and used as selective adsorbent for the extraction of lead ions from aqueous medium. Single variant experiments were carried out for all optimizations of sorption/desorption steps including pH of solution, amount of nanoparticles, mixing type/period and eluent type. An SQT with five round slots was placed onto the burner of FAAS to increase the interaction between lead atoms and light from radiation source to enhance the absorbance signals. Under the determined optimum conditions, analytical figures of merit were evaluated and the limit of detection and quantification (LOD/LOQ) values were calculated as 5.2 and 17.3 µg L^- 1, respectively. The developed method showed a linear calibration range between 25 and 250 µg L^- 1 with a good regression coefficient value (0.9995). Recovery studies were also performed with domestic wastewater samples spiked at three concentrations and percent recovery values obtained in the range of 97%-102% validated the developed method's applicability and accuracy.

Evaluated the lead levels at boiling water in clay pots and impact of the lead contaminated diet on nutritional, biochemical status of male rats

Background

For centuries, people have been using clay or earthen pots for cooking. Also, many studies indicated a contrariety from safety or danger of it. Our study aims to assess the lead concentration in boiling water in clay pots. Contaminated the diet with lead acetate and evaluated the nutritional, biochemical statues, and histological studies for male albino rats.

Step A: Ten samples of the distilled water and/or tap water were boiled in the clay pots (glaze and/or unglazed). Then, it was left to cool for either 2 or 4 h.

Step B: Thirty male albino rats divided three groups as follows: group 1: fed on basal diet (negative control), group2: fed on basal diet+466.5 mg/kg body wt of lead acetate (L1), group 3: fed on the basal diet+933 mg/kg body wt of lead acetate (L2).

Results

Lead concentrations in distilled water samples boiled in glazed clay pots were significantly higher than the negative control. Tap water samples boiled in glazed clay pots showed lead concentrations that were significantly higher than that of the positive control. Whereas, lead concentrations in distilled water boiled in the unglazed clay pots and left to cool for either 2 h or 4 h showed no significant differences compared to the negative control. Besides, rats fed L1 and L2 of lead acetate had a significant decrease in BWG and food intake compared with the negative control group. Also, rats were given lead acetate at the two levels (L1 and L2) had significantly lower levels of hemoglobin, RBCs, and WBCs compared with rats fed basic diet only (negative control). Data illustrated that the rats of groups 2 and 3 have increased significantly in GOT concentration of serum, a significant increase in cholesterol and triglycerides levels, and increased significantly in creatinine, urea, and lead concentration in serum compared with the (negative control).

Conclusion

Bring the clay pots for cooking would be unglazed and natural forming, even if glazed may be having certified a lead free.

Determination of lead at trace levels in mussel and sea water samples using vortex assisted dispersive liquid-liquid microextraction-slotted quartz tube-flame atomic absorption spectrometry

In this study, dispersive liquid-liquid microextraction (DLLME) and slotted quartz tube (SQT) were coupled to flame atomic absorption spectrometry (FAAS) to increase the sensitivity of lead. Conditions such as the formation of the lead-dithizone complex, efficiency of the DLLME method and the output of the SQT were systematically optimized to improve the detection limit for the analyte. The conventional FAAS system was improved upon by about 3.0 times with SQT-FAAS, 32 times with DLLME-FAAS and 142 times with DLLME-SQT-FAAS. The method was applicable over a wide linear range (10-500 μg L^-1). The limit of detection (LOD) determined by DLLME-SQT-FAAS for seawater and mussel were 2.7 μg L^-1 and 270 μg kg^-1, respectively. The percent recoveries obtained for mussel and seawater samples (spiked at 20 and 50 μg L^-1) were 95-96% and 98-110%, respectively.

Treatment of lead contaminated water by a PVDF membrane that is modified by zirconium, phosphate and PVA

Lead contamination is one of the most serious problems in drinking water facing humans. In this study, a novel zirconium phosphate modified polyvinyl alcohol (PVA)-PVDF membrane was developed for lead removal. The zirconium ions and PVA were firstly coated onto a PVDF membrane through crosslinking reactions with glutaraldehyde, which was then modified by phosphate. The adsorption kinetics study showed that most of ultimate uptake occurred in 5 h. The adsorption increased with an increase in pH; the optimal adsorption was achieved at pH 5.5. The experimental data were better described by Langmuir equation than Freundlich equation; the maximum adsorption capacity was 121.2 mg-Pb/g at pH 5.5, much higher than other reported adsorptive membranes. The membrane exhibited a higher selectivity for lead over zinc with a relative selectivity coefficient (Pb(2+)/Zn(2+)) of 9.92. The filtration study showed that the membrane with an area of 12.56 cm(2) could treat 13.9 L (equivalent to 73,000 bed volumes) of lead containing wastewater with an influent concentration of 224.5 μ g/L to meet the maximum contaminant level of 15 μ g/L. It was demonstrated that the membrane did well in the removal of lead in both simulated wastewater and lead-spiked reservoir water and had a good reusability in its applications. The XPS studies revealed that the lead uptake was mainly due to cation exchange between hydrogen ions and lead ions.

Synthesis, characterization and application of cyclam-modified magnetic SBA-15 as a novel sorbent and its optimization by central composite design for adsorption and determination of trace amounts of lead ions

A new, efficient, selective and relatively low cost adsorbent was developed based on Fe₃O₄@cyclam-SBA-15 for adsorption and determination of lead ions.

Estimation of lead in biological samples of oral cancer patients chewing smokeless tobacco products by ionic liquid-based microextraction in a single syringe system

Several studies have reported that the chewing habit of smokeless tobacco (SLT) has been associated with oral cancer. The aim of the present study was to evaluate the trace levels of lead (Pb) in biological samples (blood, scalp hair) of oral cancer patients and referents of the same age group (range 30-60 years). As the concentrations of Pb are very low in biological samples, so a simple and efficient ionic liquid-based microextraction in a single syringe system has been developed, as a prior step to determination by flame atomic absorption spectrometry. In this procedure, the hydrophobic chelates of Pb with ammonium pyrrolidinedithiocarbamate (APDC) were extracted into fine droplets of 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] within a syringe while using Triton X-114 as a dispersant. Factors influencing the microextraction efficiency and determination, such as pH of the sample, volume of [C4MIM][PF6] and Triton X-114, ligand concentration, and incubation time, were studied. To validate the proposed method, certified reference materials were analyzed and the results of Pb(2+) were in good agreement with certified values. At optimum experimental values of significant variables, detection limit and enhancement factor were found to be 0.412 μg/L and 80, respectively. The coexisting ions showed no obvious negative outcome on Pb preconcentration. The proposed method was applied satisfactorily for the preconcentration of Pb(2+) in acid-digested SLT and biological samples of the study population. It was observed that oral cancer patients who consumed different SLT products have 2-3-fold higher levels of Pb in scalp hair and blood samples as compared to healthy referents (p < 0.001). While 31.4-50.8% higher levels of Pb were observed in referents chewing different SLT products as compared to nonconsumers (p < 0.01).

Synthesis of robust hierarchically porous zirconium phosphate monolith for efficient ion adsorption

Hierarchically porous zirconium phosphate monoliths were synthesized and fabricated into a continuous flow setup for toxic metal ion adsorption.

Preparation, characterization and application of N-2-Pyridylsuccinamic acid-functionalized halloysite nanotubes for solid-phase extraction of Pb(II)

Halloysite nanotubes (HNTs) were chemically modified with N-2-Pyridylsuccinamic acid (PSA) to produce a new nano-adsorbent (HNTs-PSA) for selective solid-phase extraction of Pb(II). The new adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), thermogravimetric analysis (TGA), and elemental analysis to evaluate the surface modification. Under the optimized conditions (pH 5, flow rate 1.5 mL min(-1)), Pb(II) was retained on the column packed with HNTs-PSA, and then was quantitatively eluted by 1.5 mL 0.5 mol L(-1) HCl and determined by inductively coupled plasma-optical emission spectrometry. An enrichment factor of 67 was obtained using 30 mg of HNTs-PSA. The maximum adsorption capacity for Pb(II) was found to be 23.58 mg g(-1). The detection limits of this method for Pb(II) was 0.32 μg L(-1). The relative standard deviation under optimum conditions was 3.4% (n = 11). The developed method was validated by analyzing a certified reference material, and then successfully applied to the determination of Pb(II) in actual samples.

Determination of lead in biological samples of children with different physiological consequences using cloud point extraction method

In present study, lead (Pb) level in biological samples of children with physiological disorders (liver, bone, and gastrointestinal; age ranged 1-10 years) have been assessed. For comparison purpose, age-matched healthy children were also selected. Cloud point extraction (CPE) was employed for preconcentration of Pb in acid-digested biological samples prior to its determination by flame atomic absorption spectrometry (FAAS). Dithizone (diphenylthiocarbazone) and nonionic surfactant Triton X-114 (TX-114) were used as complexing reagent and extractant, respectively. The effects of several experimental variables on proposed CPE were evaluated. Under the optimum experimental conditions, the observed detection limit (LOD) and the enhancement factor (EF) were 0.08 μg L(-1) and 53, respectively. Relative standard deviation (RSD) of 10 μg L(-1) Pb was 3.4 %. It was observed that children with liver-, bone-, and gastrointestinal-related disorders had three- to fourfold higher Pb level in blood and scalp hair samples.

The use of silica gel modified with allyl 6-methyl-4-phenyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate for selective separation and preconcentration of lead in environmental samples

The aim of the present work is the assessment of a new sorbent, prepared using silica gel coated with a pyrimidine derivative (allyl 6-methyl-4-phenyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate), for extraction and preconcentration trace amount of lead from different samples prior to determination by flame atomic absorption spectrometry. Common coexisting ions did not interfere with the separation and determination of lead at pH 6, so that lead ion completely adsorbed on the column. The limit of detection based on three times the standard deviation of the blank was found to be 0.53 ng mL(-1) in original solution. Obtained sorption capacity for 1 g sorbent was 5.0 mg Pb. The linearity was maintained in the concentration range of 0.1-30.0 ng mL(-1) for the concentrated solution. Eight replicate determinations of 2.0 μg mL(-1) of lead in the final solution gave relative standard deviation of ±2.6 %. The proposed method was successfully applied to the determination trace amounts of lead in the environmental samples such as carrot, rice, zardchoobe, and real water samples.

Synthesis and application of chloromethylated polystyrene modified with 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new sorbent for the on-line preconcentration and determination of copper in water, soil, and food samples by FAAS

In this paper, we report a simple and sensitive on-line solid phase extraction system for the preconcentration and determination of Cu(II) by flame atomic absorption spectrometry (FAAS). This method is based upon the on-line retention of copper at pH 5.0 on a minicolumn packed with chloromethylated polystyrene modified by 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new solid-phase extraction (SPE) sorbent. The retained Cu(II) ions were eluted with 1.0M HNO(3), and transported directly to FAAS for determination. Several chemical and flow variables were studied and optimized for a quantitative preconcentration and determination of copper(II). At the optimized conditions, for preconcentration of 10.0 mL of a sample solution, a linear calibration graph was obtained over the concentration range of 3.00-120.0 μg L(-1) for Cu(II). The limit of detection (3σ), limit of quantification (10σ), and enrichment factor are 0.56 μg L(-1), 2.0 μg L(-1) and 41, respectively. The relative standard deviation (n = 6) at 20 μg L(-1) of Cu(II) is 2.0%. This method could be applied for determination of trace amounts of Cu(II) in water, soil, and food samples with satisfactory results.

Alumina coated with oxazolone derivative for extraction of trace amounts of cadmium and copper from water and plant samples

A solid phase extraction procedure is proposed for simultaneous separation and preconcentration trace amounts of Cu(II) and Cd(II) using alumina coated with N'-{4-[4-{1-[4-(dimethylamino)phenyl]methylidene}-5-(4-H)oxazolone]phenyle}acetamide and determination by flame atomic absorption spectrometry. Using 0.1g of the sorbent, the metal ions were sorbed at pH 7 and recovered with 5.0 mL of 0.5 mol L(-1) HNO(3). It was found that extraction can be performed from the sample volumes of 2000 and 800 mL for Cu and Cd, respectively (preconcentration factors of 400 for Cu and 160 for Cd). Obtained sorption capacities for 1g sorbent were 8 mg Cu and 14 mg Cd. The linearity was maintained in the concentration range of 0.1 ng mL(-1) to 7.0 μg mL(-1) for Cu and 0.13 ng mL(-1) to 2.0 μg mL(-1) for Cd in the original solution. Eight replicate determinations of a mixture containing 1.0 μg mL(-1) each of the elements in the final solution gave relative standard deviation ±1.6 and ±1.3% for Cu and Cd, respectively. The detection limit was calculated as 0.06 and 0.05 ng mL(-1) for Cu and Cd, respectively. The proposed method was successfully applied to the determination trace amounts of Cu and Cd in the water and plant 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.

Uses of 5-Methylresorcin-bonded polyurethan foam as a new solid phase extractor for the selective separation of mercury ions from natural water samples

In this work, 5-Methylresorcin (MR) bonded to untreated polyurethane foam (PUF) was successfully employed as a sorbent (MR-PUF) for the selective separation and determination of mercury in natural water samples. Mercury can be quantitatively recovered in the pH range of 5-7. The system presented a minicolumn packed with the new sorbent, where the sample solution was passed through it for a period of time and an eluent solution stripped out the retained mercury, which was further determined with dithizone. The new matrix was characterized by using different tools (IR spectra, stability and density). The kinetics of mercury uptake by the new matrix was found to be fast, reaching equilibrium in 20 minutes. A preconcentration factor of 350 was achieved. The proposed preconcentration procedure was applied successfully to the selective separation and determination of trace mercury in natural water samples.