Trapping Flame Atomic Absorption Spectrometry Research Articles

Cobalt separation from water and food samples based on penicillamine ionic liquid and dispersive liquid-liquid microextraction before determination by AT-FAAS

The cobalt compounds have adverse health effect on human and caused damage to the DNA cells, neurological and endocrine systems. Therefore, the separation and determination of cobalt in water and food samples must be considered. In this research, the (2S)-2-amino-3-methyl-3-sulfanylbutanoic acid (penicillamine) as a chelating agent mixed with ionic liquid (OMIM PF6) /acetone and used for extraction of cobalt from 50 mL of water samples by ultra-assisted dispersive liquid-liquid microextraction (USA-DLLME) at pH=6. Based on procedure, the samples were shaked for 5 min (25oC) and after complexation of cobalt ions by thiol and amine group of penicillamine, the ionic liquid phase separated in the bottom of the conical tube by centrifuging for 3.0 min. The upper liquid phase was vacuumed by the auto-sampler and the Co2+ ions back extracted from the ionic liquid/ penicillamine in acidic pH. Finally, the cobalt concentration in remained solution was determined by atom trap flame atomic absorption spectrometry (AT-FAAS). The main parameters such as the sample volume, the penicillamine amount, the ionic liquid amount and the shaking time were optimized. The linear range, the detection limit (LOD) and enrichment factor were obtained 1.5-62 μg L-1, 0.38 μg L-1 and 98.5, respectively (r = 0.9995, RSD%=2.2).

Separation and determination of cadmium in water samples based on functionalized carbon nanotube by syringe filter membrane- micro solid-phase extraction

A simple and fast separation of cadmium (Cd) based on functionalized carbon nanotubes with 2,3-dimercapto-1-propanol (CNTs@DHSP) was achieved in water samples before a determination by atom trap flame atomic absorption spectrometry (AT-FAAS). In this study, Cd(II) ions were extracted by syringe filter membrane-micro solid phase extraction procedure(SFM-μ-SPE). Firstly, 20 mg of the CNTs@DHSP as solid-phase added to 20 mL of water sample in a syringe, then dispersed for 3 min after adjusting pH up to 7 and pass through SFM very slowly. After extraction, the Cd(II) ions were back-extracted from SFM/CNTs@DHSP by 1.0 mL of eluent in acidic pH. Finally, the cadmium concentration was measured by AT-FAAS. Under the optimal conditions, the linear range (2–90 µg L−1), LOD (0.75 µg L−1) and enrichment factor (19.6) were obtained (RSD<1.5%). The adsorption capacity of Cd(II) with the CNTs@DHSP was obtained about 152.6 mg g-1. The method was validated by certified reference materials (SRM, NIST) and ET-AAS in water samples.

Facile synthesis of a modified HF-free MIL-101(Cr) nanoadsorbent for extraction nickel in water and wastewater samples

A novel sorbent based on MIL-101(Cr) nanoadsorbent as MOF structure was used for nickel extraction from water and wastewater samples. In this study, 30 mg of MIL-101(Cr) nanoadsorbent dispersed in 50 mL of water or wastewater samples, after sonication and adjusting pH =8.5, the nickel ions was extracted by carboxyl groups of terephthalic acid (MOF-(C6H4 (COO)-2…. Ni2+) by dispersive suspension micro solid phase extraction (DS-μ-SPE).The MOF was separated from liquid phase with filter membrane (0.2 μm), eluted with 0.5 mL of nitric acid as back-extraction solution and finally, the nickel concentration in eluent determined by atom trap-flame atomic absorption spectrometry (AT-FAAS) after dilution with DW up to 1 mL.The LOD, the linear range and preconcentration factor were achieved 1.5 µg L−1, 5-160 µg L−1 and 49.7, respectively.The absorption capacity of MOF for nickel was obtained 136.8 mg g-1.The results of procedure were validated by spiking of samples and ET-AAS analyzer.

Accurate and Sensitive Analytical Strategy for the Determination of Antimony: Hydrogen Assisted T-Shaped Slotted Quartz Tube-Atom Trap-Flame Atomic Absorption Spectrometry.

Antimony is known to have some adverse health effects on human health. Flame atomic absorption spectrometry (FAAS) is a widely used instrumental for the determination of antimony and other metals. However, it lacks the sensitivity to determine these metals at trace levels. This study was aimed at overcoming this setback by using hydrogen assisted T-shaped slotted quartz tube technique to preconcentrate and determine antimony by FAAS. All the system parameters were optimized to enhance the detection power of the system. Under the optimum experimental conditions, the limits of detection and quantification were found to be 0.75 and 2.49µgL-1, respectively with R2 value of 0.9999. Accuracy of the developed method was validated by experimental results agreeing to the certified value of a standard reference material. Recovery studies were also carried out to determine the method's applicability to tap and mineral water samples, and the results obtained were appreciable.

Determination of Bismuth in Bottled and Mineral Water Samples at Trace Levels by T-Shaped Slotted Quartz tube-Atom Trap-Flame Atomic Absorption Spectrometry

An accurate and reliable analytical method for the determination of bismuth at trace levels in bottled and mineral water samples has been developed based on hydrogen assisted T-shape slotted quartz tube-atom trap-flame atomic absorption spectrometry (T-SQT-AT-FAAS). Conventional FAAS is not sufficiently sensitive to measure trace and ultra-trace levels of metals due to the low nebulization efficiency and short residence time of atoms in the light path. To overcome this problem, atom trapping with a T-shaped slotted quartz tube was coupled to the FAAS system. Bismuth atoms were trapped on the surface of T-SQT and released by hydrogen gas, which provided a reducing environment. All of the system parameters such as flame type, hydrogen flow rate, the height of T-SQT from the burner head, and trapping period were optimized to enhance the analytical signal to attain low detection limits. After obtaining the optimum conditions, the limit of detection and limit of quantitation of the developed method were found to be 0.95 and 3.2 µg L−1, respectively. Recovery values were obtained between 90% and 104% that showed good accuracy and applicability of the proposed method to the analysis of bottled and mineral water samples.

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).

A novel analytical method for sensitive determination of lead: Hydrogen assisted T-shape slotted quartz tube-atom trap-flame atomic absorption spectrometry

Lead is a toxic metal which affects human health badly due to its high toxicity. The wide application range of lead causes environmental contamination of air, water and soil. Flame atomic absorption spectrometry is one of the simple and economical instrument used for the determination of heavy metals, but it has low sensitivity due to low sample introduction efficiency. In this study, a sensitive analytical method was developed by using T-shaped slotted quartz tube as an atom trap unit to get lower detection limit for lead. The trapped atoms were released using hydrogen gas which supplies reducing environment in T-SQT-AT-FAAS system. Factors such as trapping period, sample and fuel flow rates were optimized to obtain high sensitivity. Under the optimum conditions, limits of detection and quantitation were found to be 0.6 and 2.1μgL−1, respectively. Accuracy of the developed method was checked and results found under the optimum conditions agreed with the certified value of coal fly ash standard reference material. The developed method was applied to water samples to figure out its suitability.

Mesoporous Silica Nanoparticles as an Adsorbent for Preconcentration and Determination of Trace Amount of Nickel in Environmental Samples by Atom Trap Flame Atomic Absorption Spectrometry

A rapid enrichment method based on solid-phase extraction (SPE) has been established for preconcentration and separation of trace Ni(II) ions in water samples prior to their determination by atom trap flame atomic absorption spectrometry. A column filled with bulky NH2–UVM7 was used as the novel adsorbent. Under optimal conditions, the linear range, limit of detection (LOD), and preconcentration factor (PF) were 3–92 μg/L, 0.8 μg/L, and 100, respectively. The validity of the method was checked by the standard reference material.

In situ atom trapping of Bi on W-coated slotted quartz tube flame atomic absorption spectrometry and interference studies

Analytical performances of metal coated slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) and slotted quartz tube in situ atom trapping flame atomic absorption spectrometry (SQT-AT-FAAS) systems were evaluated for determination of Bi. Non-volatile elements such as Mo, Zr, W and Ta were tried as coating materials. It was observed that W-coated SQT gave the best sensitivity for the determination of Bi for SQT-FAAS and SQT-AT-FAAS. The parameters for W-coated SQT-FAAS and W-coated SQT-AT-FAAS were optimized. Sensitivity of FAAS for Bi was improved as 4.0 fold by W-coated SQT-FAAS while 613 fold enhancement in sensitivity was achieved by W-coated SQT-AT-FAAS using 5.0min trapping with respect to conventional FAAS. MIBK was selected as organic solvent for the re-atomization of Bi from the trapping surface. Limit of detection values for W-coated SQT-FAAS and W-coated SQT-AT-FAAS was obtained as 0.14μgmL−1 and 0.51ngmL−1, respectively. Linear calibration plot was obtained in the range of 2.5–25.0ngmL−1 for W-coated SQT-AT-FAAS. Accuracy of the W-coated SQT-AT-FAAS system was checked by analyzing a standard reference material, NIST 1643e.

Speciation of Inorganic Antimony in Food and Water Samples by Flow Injection On-line Nano γ-Alumina Micro-column Solid-Phase Extraction Coupled with Slotted Tube Atom Trapping Flame Atomic Absorption Spectrometry

Nano γ-alumina, with ultra-high specific surface area (387.2 m2 g−1), has been synthesized and used as a promising adsorbent material in solid-phase extraction. A simple, sensitive, and economic method was developed for speciation of inorganic antimony by slotted tube atom trapping flame atomic absorption spectrometry (STAT-FAAS) after flow injection on-line nano γ-alumina micro-column solid-phase extraction. In this method, Sb(III)–diethyldithiocarbamate (DDTC) complexes produced on-line from DDTC and Sb(III) were adsorbed by the synthesized γ-alumina nanoparticles in a micro-column, then eluted by 1.0 mol L−1 HNO3 in methanol, whereas Sb(V) remained in aqueous solution. The total inorganic Sb was determined by the same procedure after Sb(V) was reduced with thiourea. Under optimal conditions, the enrichment factor was 56.5 and the detection sensitivity was improved 40-fold for antimony by STAT-FAAS compared to conventional FAAS. The limit of detection was 6.0 ng L−1 for Sb(III) and 8.2 ng L−1 for Sb(V), respectively. The intra-day precision (RSDs, n = 11) were 2.8 % for Sb(III) and 3.5 % for Sb(V), respectively, and the inter-day precision (n = 3) were 7.1 % for Sb(III) and 8.4 % for Sb(V), respectively. The recoveries for the spiked samples were 93–107 %. The proposed method was applied to speciation of inorganic antimony in water and food samples successfully.

Development of a sensitive method for lead determination by flame atomic absorption spectrometry using slotted quartz tube in-situ atom trapping and metal coatings

Flame atomic absorption spectrometry (FAAS) still keeps its importance despite the relatively low sensitivity, because it is a simple and economical technique for determination of metals. In recent years, atom traps have been developed to increase the sensitivity of FAAS. Although the detection limit of FAAS is only at the level of mgL−1, with the use of atom traps it can reach to the level of ngmL−1. Slotted quartz tube (SQT) is one of these atom traps; it is applied for determination of volatile elements. It is economical, commercially available and easy to use. In this study, a sensitive analytical method has been developed for the determination of lead with the help of SQT. 1472 fold sensitivity enhancement was obtained using the uncoated slotted quartz tube atom trap flame atomic absorption spectrometry (SQT-AT-FAAS) method at a sample suction rate of 7.4mLmin−1 for 4.0min collection with respect to FAAS. To obtain a further sensitivity enhancement, the inner surface of SQT was coated with several kinds of transition metals. The best sensitivity enhancement, 4600 fold, was obtained by the Ta-coated-SQT-AT-FAAS. In addition, the chemical nature of Pb trapped on quartz and Ta surface, and the chemical nature of Ta on quartz surface were investigated by X-ray photoelectron spectroscopy (XPS).

Speciation Determination of Chromium(VI) and Chromium(III) in Soil Samples after Cloud Point Extraction

To measure the different activity of chromium(VI) and chromium(III) in soil samples, chromium(VI) and total chromium (CrVI + CrIII) was extracted by KCl extracting agent and alkali fusion, respectively. Cloud point extraction (CPE) for speciation determination of chromium with double-slotted quartz tube atom trap–flame atomic absorption spectrometry (STAT-FAAS) was developed. Preconcentration of chromium(VI) and total chromium in different pH solutions was achieved by CPE, with ammonium pyrrolidine dithiocarbamate (APDC) as the chelating agent and Triton X-114 as the cloud point extractant. The conditions of CPE and determination were studied. Under the optimal conditions, the enrichment factor was 50 for chromium from the initial 100-mL sample solution to the final 2-mL determined solution. Compared to the FAAS method, the sensitivity was improved seven-fold for chromium by the STAT-FAAS method. The limit of detection was 0.082 µg/L for chromium.

Determination of lead by hydride generation atom trapping flame atomic absorption spectrometry

An atom trapping approach is described for the determination of lead by hydride generation flame atomic absorption spectrometry. Lead hydride (PbH4), generated on-line by reacting lead in hydrochloric acid–potassium ferricyanide medium with sodium borohydride (NaBH4), was trapped on the interior walls of a slotted T-tube under highly oxidizing flame conditions. Atomization was achieved by aspirating 50 µL of methyl isobutyl ketone (MIBK) to the flame. Optimization of the experimental parameters for the generation and collection of lead hydride was described to achieve the highest peak height sensitivity. The detection limits were 0.075, 0.047 and 0.028 µg L−1 for 2.6, 5.2 and 7.8 mL of blank solution (n = 13), respectively. Calibration was linear up to 3.0 µg L−1 for a 30-s trapping period. The relative standard deviation was between 2 and 4%. The method was successfully applied to the determination of Pb in NIST certified reference materials, San Joaquin Soil (SRM 2709) and Apple Leaves (SRM 1515).

Determination of total antimony and inorganic antimony species by hydride generation in situ trapping flame atomic absorption spectrometry: a new way to (ultra)trace speciation analysis

The analytical performance of non-chromatographic coupled hydride generation, integrated atom trap (HG-IAT) atomizer flame absorption spectrometry (FAAS) systems were evaluated for the speciation analysis of antimony in environmental samples. Antimony, using formation of stibine (SbH3) vapors were atomized in an air–acetylene flame-heated IAT. A new design of HG-IAT-FAAS hyphenated technique that would exceed the operational capabilities of existing arrangements (a water-cooled single silica tube, double-slotted quartz tube or an “integrated trap”) was investigated. For the estimation of Sb(III) and Sb(V) concentrations in samples, the difference between the analytical sensitivities of the absorbance signals obtained for antimony hydride without and with previous treatment of samples with L-cysteine can be used. The concentration of Sb(V) was calculated by the difference between total Sbtot and Sb(III). A dramatic improvement in detection limit was achieved compared with that obtained using either of the atom trapping techniques, presented above, separately. This novel approach decreases the detection limit down to low pg mL–1 levels. The concentration detection limit, defined as 3 times the blank standard deviation (3sigma), was 0.2 ng mL–1. For a 120 s in situ pre-concentration time (sample volume of 2 mL), sensitivity enhancement compared to flame AAS, was 550 fold for Sb, using hydride generation-atom trapping technique. The sensitivity can be further improved by increasing the collection time. The precision, expressed by RSD, was 8.0% (n = 6) for Sb. The designs studied include slotted tube, water-cooled single silica tube and integrated atom traps. Reference and real sample materials were analyzed. The accuracy of the method was verified by the use of certified reference materials (NIST SRM 2704 Buffalo River Sediment, SRM 2710 Montana Soil, SRM 1633a Coal Fly Ash, SRM 1575 Pine Needles, SRM 1643e Trace Elements in Water) and by aqueous standard calibration technique (solutions). The measured Sb content, in reference materials, were in satisfactory agreement with the certified values. The hyphenated technique was applied for antimony determinations in soil, sediment, coal fly ash, sewage and river water.

Determination of tellurium by hydride generation with in situ trapping flame atomic absorption spectrometry

The analytical performance of coupled hydride generation — integrated atom trap (HG-IAT) atomizer flame atomic absorption spectrometry (FAAS) system was evaluated for determination of Te in reference material (GBW 07302 Stream Sediment), coal fly ash and garlic. Tellurium, using formation of H 2Te vapors, is atomized in air–acetylene flame-heated IAT. A new design HG-IAT-FAAS hyphenated technique that would exceed the operational capabilities of existing arrangements (a water-cooled single silica tube, double-slotted quartz tube or an “integrated trap”) was investigated. An improvement in detection limit was achieved compared with using either of the above atom trapping techniques separately. The concentration detection limit, defined as 3 times the blank standard deviation (3 σ), was 0.9 ng mL − 1 for Te. For a 2 min in situ pre-concentration time (sample volume of 2 mL), sensitivity enhancement compared to flame AAS, was 222 fold, using the hydride generation — atom trapping technique. The sensitivity can be further improved by increasing the collection time. The precision, expressed as RSD, was 7.0% ( n = 6) for Te. The designs studied include slotted tube, single silica tube and integrated atom trap-cooled atom traps. The accuracy of the method was verified using a certified reference material (GBW 07302 Stream Sediment) by aqueous standard calibration curves. The measured Te contents of the reference material was in agreement with the information value. The method was successfully applied to the determination of tellurium in coal fly ash and garlic.

Determination of cadmium and lead in reference materials by volatile species generation with in situ trapping flame atomic absorption spectrometry

The analytical performance of coupled volatile species generation-integrated atom trap (VSG-IAT) atomizer flame atomic absorption spectrometry (FAAS) system was evaluated for determination of Cd and Pb in reference materials. Lead using formation of PbH 4 and Cd 0 vapors are atomized in air-acetylene flame-heated IAT. A new design of VSG-IAT-FAAS hyphenated technique that would exceed the operational capabilities of existing arrangements (a water-cooled single silica tube, double-slotted quartz tube or an “integrated trap”) was investigated. A dramatic improvement in detection limit was achieved compared with that obtained using either of the above atom trapping techniques separately. The concentration detection limits, defined as 3 times the blank standard deviation (3 σ), were 0.05 and 0.40 ng mL − 1 for Cd and Pb, respectively. For a 120 s in situ pre-concentration time, sensitivity enhancement compared to flame AAS, was 500 and 575 folds for Cd and Pb, respectively, using volatile species generation-atom trapping technique. The sensitivity can be further improved by increasing the collection time. The precision, expressed as RSD, was 4.4% and 4.1% ( n = 6) for Cd and Pb, respectively. The designs studied include slotted tube, single silica tube and integrated atom trap-cooled atom traps. The accuracy of method was verified using certified reference materials (PLANTS 3 and IAEA/W-4) by standard addition calibration technique. The measured Cd and Pb contents in two reference materials were in satisfactory agreement with the certified values.

On-line Hyphenation of Hydride Generation with in situ Trapping Flame Atomic Absorption Spectrometry for Arsenic and Selenium Determination

The analytical performances of coupled hydride generation, integrated atom trap (HG-IAT) atomizer flame atomic absorption spectrometry (FAAS) systems were evaluated for determination of As and Se in biological and environmental reference materials. Arsenic and Se hydrides are atomized in air-acetylene flame-heated IAT. A new design of HG-IAT-FAAS hyphenated technique that would exceed the operational capabilities of existing arrangements (a water-cooled single silica tube, double-slotted quartz tube or an "integrated trap") was investigated. A dramatic improvement in detection limit was achieved compared with that obtained using anyone of the above atom trapping techniques separately. The concentration detection limits were 4 and 3 ng ml(-1) for As and Se, respectively. For a 2 min in situ preconcentration time, sensitivity enhancement, compared to FAAS, were 875 and 833 folds for As and Se, respectively, using hydride generation, atom trapping technique. The sensitivity can be further improved by increasing the collection time. The relative standard deviations (RSDs) are of the order of 5 - 9% for this hyphenated technique. The designs studied include slotted tube, water-cooled single silica tube and integrated atom trap. The accuracy was assessed by analyses of NRCC DOLT-2 (Dogfish Liver) and NIST SRM 1648 (Urban Particulate Matter) reference materials. The measured As and Se contents in two reference materials were in satisfactory agreement with the certified values.

Derivative flame atomic absorption spectrometry and its application in trace analysis

Flame atomic absorption spectrometry (FAAS) is an accepted and widely used method for the determination of trace elements in a great variety of samples. But its sensitivity doesn’t meet the demands of trace and ultra-trace analysis for some samples. The derivative signal processing technique, with a very high capability for enhancing sensitivity, was developed for FAAS. The signal models of conventional FAAS are described. The equations of derivative signals are established for FAAS, flow injection atomic absorption spectrometry (FI-FAAS) and atom trapping flame atomic absorption spectrometry (AT-FAAS). The principle and performance of the derivative atomic absorption spectrometry are evaluated. The derivative technique based on determination of variation rate of signal intensity with time (dI/dt) is different from the derivative spectrophotometry (DS) based on determination of variation rate of signal intensity with wavelength (dI/dλ). Derivative flame atomic absorption spectrometry (DFAAS) has higher sensitivity, lower detection limits and better accuracy. It has been applied to the direct determination of trace elements without preconcentration. If the derivative technique was combined with several preconcentration techniques, the sensitivity would be enhanced further for ultra-trace analysis with good linearity. The applications of DFAAS are reviewed for trace element analysis in biological, pharmaceutical, environmental and food samples.

Determination of trace lead in chinese herbs by derivative flame atomic absorption spectrometry using an atom-trapping technique.

A simple and sensitive method is described for the determination of trace lead in Chinese herbs by derivative atom trapping flame atomic absorption spectrometry (D-AT-FAAS) with a modified water-cooled quartz atom-trapping tube. The effects that influence the sensitivity of the derivative method, such as the trap position, the flame conditions and the collection time, were studied. The characteristics of the derivative atom trapping-atomic absorption signal and the linear nature of the working curve were investigated. The sensitivity of the derivative method is 2 or 3 orders of magnitude higher than that of FAAS, and the detection limit improved by 1 or 2 orders of magnitude. Satisfactory recoveries of 93.0-108.0% for lead were obtained by determining several Chinese herbs with a relative standard derivation range of 2.9 to 4.2%.

Determination of cadmium in flour by atom trapping flame atomic absorption spectrometry using derivative signal processing

A method is described for the determination of cadmium by atom trapping flame atomic absorption spectrometry (AT-FAAS) using derivative signal processing. The detection limit and sensitivity of the proposed method were improved by two and three orders of magnitude over those of conventional FAAS with 1–3 min collection time, respectively. The characteristic concentration (gives a derivative absorbance of 0.0044) and detection limit (3σ) of cadmium were 0.027 and 0.019 μg l −1, respectively, for a 1 min collection time and a 10 mV min −1 sensitivity range. The proposed method was applied to the determination of cadmium in flour samples with a recovery range of 94.7–119%.