Determination of Cadmium in Fruit and Vegetables by Ionic Liquid Magnetic Microextraction and Flame Atomic Absorption Spectrometry

An ionic liquid-linked dual magnetic microextraction procedure is reported for cadmium(II) with flame atomic absorption spectrometry. Cadmium was complexed with pyrolidine dithiocarbamate and the chelate was extracted into the fine droplets of 1-butyl-3-methylimidazolium hexafluorophosphate by using a vortex mixer with Fe₃O₄ nanoparticles. Plackett–Burman design was used to optimize relevant parameters of the method, including the pH, the volume of ionic liquid, the amount of ammonium pyrolidine dithiocarbamate, the mass of magnetic nanoparticles, and the vortex time. The pH, volume of ionic liquid, and mass of ammonium pyrolidine dithiocarbamate significantly affected the recovery. The limit of detection, preconcentration factor, and relative standard deviation were 0.32 µg L^?1, 80, and 3.4%, respectively. The procedure was validated by the analysis of spinach leaves standard reference material 1570a and recovery measurements. Practical application of the method involved the determination of cadmium in fruit and vegetables.     

螯合树脂在线富集火焰原子吸收法测定痕量铅和镉

在pH=4.88的乙酸-乙酸钠缓冲溶液中,用螯合离子交换树脂富集铅和镉,以1.50mol/L HNO3作洗脱液,火焰原子吸收法测定洗脱液中痕量铅和镉。该方法对铅和镉的线性范围分别是4.0～80.0μg/L和2.0～30.0μg/L,检出限分别为1.3μg/L和0.7μg/L。该方法用于地表水中痕量铅和镉的测定,分析结果满意。     

Solid Phase Extraction of Trace Amounts of Cadmium with Cetyltrimethylammonium Bromide‐Coated Magnetic Nanoparticles Prior to Its Determination by Flame Atomic Absorption Spectrometry

A solid‐phase extraction (SPE) method has been presented for the selective separation and preconcentration of trace amounts of cadmium using cetyltrimethylammonium bromide (CTAB)‐coated Fe₃O₄ nanoparticles (NPs). The method is based on the sorption of cadmium as CdI₄^2? complex on the positively charged surface of the CTAB‐coated Fe₃O₄ NPs. The preconcentrated cadmium is then desorbed from the surface of the sorbent and is determined by flame atomic absorption spectrometry. The influences of the experimental parameters including pH of the solutions, amount of surfactant, iodide concentration, sample volume, eluent type and volume on the recovery of the analyte ions were investigated. Under the optimum conditions by the extraction of 500 mL of aqueous samples, a preconcentration factor of 250 was achieved. The detection limit (3s) was 0.06 μg L^?1, and the relative standard deviations at 0.5 and 5 μg L^?1 levels of cadmium (n = 10) were 3.2 and 1.9% respectively. The proposed method was successfully applied to the determination of cadmium in water samples. The accuracy was evaluated through the recovery experiments and independent analysis by the graphite furnace atomic absorption spectrometry (GFAAS).     

流动注射在线液-液萃取火焰原子吸收法测定水中痕量铅

提出了一种流动注射在线液－液萃取火焰原子吸收直接测定水中痕量铅的分析方法。实验以APDC为螯合剂,用MIBK为萃取剂,研究了在线萃取中各种实验参数、酸度条件的影响,考察了共存元素的干扰。方法的RSD（n=12)为2．7％,测定检出限为3．1μg/L,回收率为96％－106％。     

Solid Phase Extraction of Lead(II) by Sorption on Grinded Eucalyptus Stem and Determination with Flame Atomic Absorption Spectrometry

A sensitive and simple solid‐phase preconcentration procedure for the determination of trace amount of lead by flame atomic absorption spectrometry (FAAS) is developed. The method is based on the adsorption of Pb²⁺ on the column of fine grinded eucalyptus stem adsorbent, elution of the column by nitric acid and subsequent determination by FAAS. The effect of different variables such as pH, eluent type, flow rate and interfering ions on the recovery of the analyte was investigated and optimum conditions were established. The adsorption of lead onto fine grinded eucalyptus stem can formally be described by a Langmuir equation with a maximum adsorption capacity of 4.49 mg g^?1. A preconcentration factor of 50 was achieved using the optimum conditions. The calibration graph was linear in the range 10–125 ng mL^?1 of lead in the initial solution with r = 0.9982. The limit of detection based on 3S_b criterion was 4.5 ng mL^?1 and the relative standard deviation for eight replicate measurements of 30 and 80 ng mL^?1 of iron was 3.6 and 2.8%, respectively. The method was successfully applied to the determination of lead added to well, tap and wastewater samples.     

流动注射-在线富集火焰原子吸收分光光度法测定痕量铅

本文报道在流动注射分析体系中用装有黄原脂棉的微型柱对溶液中Pb2 进行在线富集后,用3.0 mol/L盐酸洗脱柱上富集的Pb2 ,然后采用火焰原子吸收光谱法在线测定痕量Pb2 ,方法的线性范围为0.5～100μg/L。与未富集前相比,测定的灵敏度可提高65倍。方法用于环境水样中痕量Pb2 的测定,回收率在97.0%～102%之间,相对标准偏差小于4.0%,分析结果满意。     

火焰原子吸收光谱法快速测定水性漆中镉

研究了水性漆中镉的原子吸收法分析。采用干灰化法处理漆片试样,硝酸消解,ＦＡＡＳ测定,加标回 在８７．８￣９６．４％     

原子捕集火焰原子吸收法测定水中镉

采用自制原子捕集装置，选择了镉在不锈钢管上捕集的合适条件，使测镉的灵敏度比常规火焰原子吸收法提高了116倍。应用于工业废水中痕量镉的测定，获得满意结果。     

Solid Phase Extraction and Determination of Trace Amounts of Lead(II) Using Octadecyl Membrane Disks Modified by a New Schiff's Base and Flame Atomic Absorption Spectrometry

A highly selective, facile and reliable method for separation and preconcentration of the trace amounts of lead present in aqueous samples is introduced. By passing the solutions through an octadecyl silica membrane disk modified by a novel Schiff's base, Pb²⁺ ions are adsorbed quantitatively while almost all interfering ions pass through the disk. The retained lead(II) ions are then eluted from the disk surface by a minimal amount of organic eluents. The influences of pH, sample flow‐rates and interfering ions are also investigated. The proposed method permits an enrichment factor of about 500 or higher and a detection limit of 0.0065 ng mL^?;1.     

Unmodified Multi-Walled Carbon Nanotubes as Sorbent Material in Flow Injection on-Line Sorbent Extraction Preconcentration System for Cadmium Determination by Flame Atomic Absorption Spectrometry

Unmodified multi-walled carbon nanotubes (MWCNTs) were demonstrated as hydrophobic sorbent material for flow injection on-line microcolumn preconcentration coupled with flame atomic absorption spectrometry for cadmium determination in natural water samples. The method was based on on-line chelate complex formation between the analyte with sodium diethyldithiocarbamate and retention onto the surface of MWCNTs. Quantitative elution of the analyte was achieved with methanol which was whereupon delivered to the FAAS nebulizer for atomization and measurement. The microcolumn was packed with a mixture of MWCNTs and silica beads in order to minimize the generated back-pressure in the flow system which arises from the nano dimensions of MWCNTs. All factors affecting the performance of the proposed method were studied thoroughly. For a 180 s preconcentration time the enhancement factor was 54, the detection limit (3s) was 0.24 µg L^?1, and the precision as relative standard deviation at a 5.0 µg L^?1 Cd(II) concentration level was 3.2%. The method was applied to the analysis of environmental water samples and the accuracy evaluated via certified reference material and recovery experiments.     

Online Solid-Phase Extraction of Cd(II), Cu(II), and Co(II) Using Covalently Attached Bis(salicylaldimine) to Silica Gel for Determination in Food and Water by Flame Atomic Absorption Spectrometry

In this study, a novel sorbent material bearing a bis(aldimine) group was designed and successfully synthesized by covalently bonding a 2-[N,N′-bis(salicylaldimine)]aminoethyl amine ligand to the silica gel surface that was characterized by carbon, hydrogen, and nitrogen elemental analysis, thermogravimetric analysis, and the Fourier transform infrared spectroscopy technique. The sorbent was used for the online solid-phase extraction (SPE) of Cd(II), Cu(II), and Co(II) ions for their determination at trace concentration levels by flame atomic absorption spectrometry. The effective factors for the online SPE such as the pH and the flow rate of the sample solution, and type, volume, and flow rate of eluent were investigated. The concentration levels of Cd(II), Cu(II), and Co(II) were measured in certified reference materials including Virginia tobacco leaves (CTA-VTL-2) and water-trace elements (NWTM-15.2) to validate this method. The metal levels in environmental water were determined by this method, and the values were checked by spiking and recovery experiments and independent analysis by inductively coupled plasma-mass spectrometry. The adsorption capacities of the sorbent were found to be 41.2, 31.6, and 25.6?mg/g for Cd(II), Cu(II), and Co(II), respectively. This method was also successfully used for the determination of Cd(II), Cu(II), and Co(II) concentrations in rice and molasses.     

Preconcentration,Determination and Speciation of Chromium(III) Using Solid Phase Extraction and Flame Atomic Absorption Spectrometry

A facile, reliable and reproducible method for speciation and determination of the traces amounts of chromium(III) in waste water has been developed. The method was based on complex formation on the surface of the ENVI‐18 DSK^? disks followed by stripping of the retained species by minimum amounts of appropriate organic solvents. The elution was efficient and quantitative. The effects of potential interfering ions, pH, ligand amount, stripping solvent, and sample flow rate were also investigated. Under the optimal experimental conditions, the break‐through volume was found to be about 1500 mL providing a preconcentration factor of 300. The maximum capacity of the disks was found to be 225 ± 3.9 μg for Cr³⁺. A limit of detection of 0.02 ng.mL ^?1 was obtained, and the method was applied for determination of chromium in electroplating industries waste water located in the eastern regions of Tehran.     

Preconcentration and Determination of Copper(II) by Novel Solid-Phase Extraction and High-Resolution Continuum Source Flame Atomic Absorption Spectrometry

Amberlite XAD-4 modified with N-para-anisidine-3,5-di-tert-butylsalicylaldimine was investigated as a new chealting sorbent for the selective separation and preconcentration of Cu(II). The metal ion was retained by chemical sorption on the modified resin, eluted by hydrochloric acid, and determined by high-resolution continuum source flame atomic absorption spectrometry. The prepared resin was characterized for the solid-phase extraction of Cd²⁺, Co²⁺, Cr³⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ in a column. The influence of the pH, the mass of solid phase, eluent, flow rate, and sample volume was optimized. Using the optimum conditions, only Cu(II) showed quantitative sorption at the 95% confidence level, and the recoveries of the other metal ions were below 80%. A preconcentration factor 125 was obtained for Cu(II) with a limit of detection of 0.56?µg?L^?1. The method was used for the determination of Cu(II) in tap water, river water, tomato leaves, and fish. The relative standard deviation and the relative error were lower than 7%.     

磁性碳纳米管固相萃取-原子荧光光谱法测定水中痕量镉

建立了检测水中痕量镉的磁性固相萃取-原子荧光光谱法。制备磁性碳纳米管,以其作为固相萃取吸附剂用来萃取和富集水中的痕量镉,采用氢化物发生-原子荧光光谱法进行检测。在最佳条件下,镉在0.05~5.0μg·L-1范围内呈线性,检出限(3σ)为1.6 ng·L-1。加标回收率在97.1%~101%之间,测定值的相对标准偏差在1.6%~4.8%之间。方法用于分析标准物质,测定值与认定值相符。     

Coprecipitation for the Determination of Copper(II), Zinc(II), and Lead(II) in Seawater by Flame Atomic Absorption Spectrometry

A TiO(OH)₂ precipitate was used for the preconcentration of copper(II), zinc(II), and lead(II) in seawater prior to determination by flame atomic absorption spectrometry. The influence of pH, sample volume, amount of precipitate, and centrifugation time were optimized for quantitative recoveries of the analytes. Under the optimum conditions, the detection limits of copper(II), lead(II), and zinc(II) were 4.3, 9.7, and 9.6 micrograms per liter, respectively. The recoveries of analytes were between 95.00 and 103.00 percent with the relative standard deviation below 6 percent. The procedure was validated by the analysis of NASS-5 and SPS-WW1 Batch 109 standard reference materials and the procedure was successfully applied to seawater.     

Simultaneous Determination of Aluminum,Cadmium and Lead in Whole Blood by Simultaneous Atomic Absorption Spectrometry with Oxygen Charring

A method for the simultaneous determination of aluminum (Al), cadmium (Cd) and lead (Pb) in whole blood has been developed by using simultaneous atomic absorption spectrometry (SIMAAS) with oxygen charring. The optimized conditions for the simultaneous determination of Al, Cd and Pb were obtained in the presence of palladium (Pd) as the chemical modifier, using 600 °C and 2400 °C as the pyrolysis and the atomization temperature, respectively. The whole blood samples were diluted 1+5 (v/v) directly with 0.1% (v/v) Triton X‐100. Oxygen was employed to eliminate the interference of carbonaceous residues in the charring step before pyrolysis. The calibration curves were carried out with aqueous standard solutions and the linear ranges were 0–40 ng mL⁻¹, 0–4 ng mL⁻¹ and 0–40 ng mL⁻¹ for Al, Cd and Pb, respectively. The detection limits were 0.96 ng mL⁻¹ (19.2 pg) for Al, 0.03 ng mL⁻¹ (0.6 pg) for Cd and 0.60 ng mL⁻¹ (12.0 pg) for Pb. The spiked recoveries of Al, Cd and Pb in whole blood were 98.0%, 100.0% and 101.7%, respectively. The accuracy of the proposed method was evaluated with the analysis of a whole blood certified reference material (Seronorm, level 2). The found concentrations were in agreement with the recommended values. The proposed method has been successfully applied to the simultaneous determination of Al, Cd and Pb in whole blood of healthy volunteers before and after eating barbecued foods.     

Determination of Traces of Chromium in Foods by Solvent Extraction Flame Atomic Absorption Spectrometry

ABSTRACT

A simple methodology for Cr(III) determination in foods was developed through flame atomic absorption spectrometry with air/acetylene after a fast oxidation of Cr(III) with KM_nO₄ and pre-concentration of Cr(VI) in MIK as C_rO₂CI₂. A limit of detection and limit of quantification (LOQ), respectively, of 4 μg/Kg and 13 μg/Kg Cr(III) were obtained in commercialized foods in São Paulo, Brazil. Two certificated samples as well as some food samples were analyzed with good results. A study of sample treatment showed that the dry ash method is the best.     

碘化钾―甲基异丁基甲酮萃取―火焰原子吸收法测定土壤中的痕量铅

土壤样品经微波消解,在优化的条件下,用碘化钾―甲基异丁基甲酮萃取,采用火焰原子吸收光谱法测定其中的铅。结果表明,在盐酸质量分数为1%～2%,萃取时间为2 min,平衡时间为15 min,样品中的铅能被定量萃取。方法检出限为0.1 mg/kg。方法用于土壤标准样品测定,测定值与标准值相符,相对标准偏差为1.2%～1.4%,相对误差为0.8%～2.5%。实际土壤样品的测定结果显示,回收率为99.8%～100.4%。     

Determination of Manganese(II) with Preconcentration on Almond Skin and Determination by Flame Atomic Absorption Spectrometry

Almond skin was used as a biosorbent by solid-phase extraction for the preconcentration of manganese(II) before the determination by flame atomic absorption spectrometry. Characterization of almond skin was performed by infrared spectroscopy. The functional groups of the almond skin surface were shown to be beneficial for the adsorption of manganese(II). At pH 6.0, the manganese(II) ions were retained on the almond skin and afterward quantitatively eluted using 1.5?mol?L^?1 nitric acid. The pH, flow rate and volume of sample, concentration, and flow rate of eluent and interfering ions were characterized. Using a sample size of 30?mL, a linear dynamic range of 1–120?µg?L^?1 was obtained. A detection limit of 0.24?µg?L^?1 manganese(II) and a relative standard deviation of 1.6% at 30?µg?L^?1 were achieved. The accuracy of the present procedure was evaluated by the determination of manganese(II) in a certified reference material (GSB07-1189-2000). The protocol was also used for the determination of manganese(II) in wastewater. The fortified recoveries were from 99.0 to 99.4%.