Halocarbons in Antarctic Surface Waters

Abstract

Surface water samples taken during the 1988–89, 1989–90 and 1990–91 Italian expeditions were analyzed for the presence of carbon tetrachloride, trichloroethylene and tetrachloroethylene. The sample analysis was carried out by solvent extraction and capillary GC-ECD-MS determination. The above-mentioned halocarbons were at ng/l level in all water samples investigated.     

Speciation analysis of inorganic vanadium (V(IV)/V(V)) by graphite furnace atomic absorption spectrometry following ion-exchange separation

A sensitive and simple method of ion-exchange resin separation and graphite-furnace atomic absorption spectrometry (GFAAS) detection was proposed for the determination of inorganic vanadium species. Methylene Blue (MB) was used as a chelating agent of V(V) for ion-exchange separation. The complex of V(V) and MB could be trapped by ion-exchange resin at pH 3.0 and eluted by 1.0?mol?L^?1 NaOH. The vanadium species was determined subsequently by GFAAS. The concentration of V(IV) was calculated by subtracting the V(V) concentration from the total concentration of vanadium. Under the optimized experimental conditions, the detection limit of V(V) is 0.48?µg?L^?1 with RSD of 2.6% (n?=?5, c?=?2.0?µg?L^?1). In order to verify the accuracy of the method, a certified reference soil sample was analyzed, and the results obtained were in good agreement with the certified values. The range of recovery for V(IV) and V(V) was 97.8–99.3% and 101.7–103.6%, respectively. The proposed method was applied to the speciation analysis of vanadium in lake-water samples.     

Hollow fiber liquid phase microextraction combined with graphite furnace atomic absorption spectrometry for the determination of methylmercury in human hair and sludge samples

Two methods, based on hollow fiber liquid–liquid–liquid (three phase) microextraction (HF-LLLME) and hollow fiber liquid phase (two phase) microextraction (HF-LPME), have been developed and critically compared for the determination of methylmercury content in human hair and sludge by graphite furnace atomic absorption spectrometry (GFAAS). In HF-LPME, methylmercury was extracted into the organic phase (toluene) prior to its determination by GFAAS, while inorganic mercury remained as a free species in the sample solution. In HF-LLLME, methylmercury was first extracted into the organic phase (toluene) and then into the acceptor phase (4% thiourea in 1 mol L^− 1 HCl) prior to its determination by GFAAS, while inorganic mercury remained in the sample solution. The total mercury was determined by inductively coupled plasma-mass spectrometry (ICP-MS), and the levels of inorganic mercury in both HF-LLLME and HF-LPME were obtained by subtracting methylmercury from total mercury. The factors affecting the microextraction of methylmercury, including organic solvent, extraction time, stirring rate and ionic strength, were investigated and the optimal extraction conditions were established for both HF-LLLPME and HF-LPME. With a consumption of 3.0 mL of the sample solution, the enrichment factors were 204 and 55 for HF-LLLPME and HF-LPME, respectively. The limits of detection (LODs) for methylmercury were 0.1 μg L^− 1 and 0.4 μg L^− 1 (as Hg) with precisions (RSDs (%), c = 5 μg L^− 1 (as Hg), n = 5) of 13% and 11% for HF-LLLPME–GFAAS and HF-LPME–GFAAS, respectively. For ICP-MS determination of total mercury, a limit of detection of 39 ng L^− 1 was obtained. Finally, HF-LLLME–GFAAS was applied to the determination of methylmercury content in human hair and sludge, and the recoveries for the spiked samples were in the range of 99–113%. In order to validate the method, HF-LLLME–GFAAS was also applied to the analysis of a certified reference material of NRCC DORM-2 dogfish muscle, and the determined values were in good agreement with the certified values.     

石墨炉原子吸收光谱无标样分析法的研究：Ⅳ.实际样品的分析

以有机基体改进剂、管壁原子化、热解涂层石墨管、峰面积积分吸收信号、Ｄ２灯或Ｚｅｅｍａｎ效应扣除背景，有效地控制和消除了海水基体对Ｃｄ，Ｃｏ，Ｃｒ，ＣｕＭｎ，ＮｉＰｂ等元素的干扰。在此前提下，用ＧＦＡＡＳ无标样分析汉分析了实验海水样品中的痕量元素，与极谱法及间接火焰原子吸收法测得的结果相符，测得质控海水样品的结果与标准值亦很吻合，而且检出限和回收率都达达到要求。     

Trace element determination in contaminated sediments and soils by ultrasonic slurry sampling and Zeeman graphite furnace atomic absorption spectrometry

Ultrasonic suspension of powder samples in combination with graphite furnace atomic absorption spectrometry (GFAAS) has been proven to be a promising method for the analysis of the total content of As, Cd, Cr, Cu, Ni and Pb in sediments and soils. The samples have been ground to a grain size <63 m. The calibration has been carried out with aqueous solutions of the analytes, with the exception of Cr which requires a calibration with suspensions of a suitable reference sample. The reproducibility has been slightly lower than for measurements obtained with solutions. Advantages are the considerable simplification of the sample preparation and the reduction of blank values. Comparative analyses have shown a good agreement of the results with those obtained by other methods.     

Highly Oriented Pyrolytic Graphite as a Platform for Atomic Absorption Spectrometry

Compared to pyrolytic graphite (PG) and pyrolytically coated polycrystalline graphite (PCPG), which are commonly employed substrates for graphite furnace atomic absorption spectrometry (GFAAS), highly oriented pyrolytic graphite (HOPG) is characterized by a high degree ofc-axis alignment with relatively few active sites and imperfections present on the surface. The usefulness of HOPG and commercial PG platforms for the determination of lead, copper, and aluminum by GFAAS was compared. Qualitative comparison of the absorption profiles and temperature optimizations suggest that lead, copper with a chemical modifier (palladium), and aluminum interact similarly with the two graphite substrates, while copper without a modifier interacts less strongly with HOPG than with PG. These results are in agreement with previous studies that have demonstrated that copper interacts strongly with PG and PCPG. HOPG and PG were employed for the determination of a pine needles standard reference material (SRM) and Fraser fir (Abies fraseri) samples. The analyses of the SRM gave good agreement with the certified value using both substrates, and comparable values were obtained for the samples. These results suggest that HOPG may be useful as a model for PG or PCPG when techniques such as scanning tunneling microscopy that require a high degree ofc-axis alignment are employed.     

Single granular activated carbon microextraction and graphite furnace atomic absorption spectrometry determination for trace amount of gold in aqueous and geological samples

A new and simple method was developed for preconcentration trace amount of gold in aqueous and mineral samples. The method was based on the sorption of gold on granular activated carbon (AC) in acidic medium (hydrochloric acid) and subsequently direct determination by graphite furnace atomic absorption spectrometry (GFAAS). A small particle of adsorbent was delivered to small volume of sample. After extraction, AC removed and analyzed directly by GFAAS. Several factors influencing the extraction efficiency, such as the hydrochloric acid concentration, sample volume and extraction time were studied as well as effect of potential interfering ions. The preconcentration factor 50 was obtained. The limit of detection (LOD) of gold in water and soil samples was 0.007 μg L^− 1 and 0.9 ng g^− 1, respectively. The proposed method was applied successfully to the determination of trace amount of gold in environmental and geological samples. In order to validate the developed method, two certified reference materials: Platinum Ore (SARM-7B) and Copper Ore Mill Heads (No. 330) were analyzed and the determined values obtained were in good agreement with the certified values and recovery was obtained in the range of 80-118%. The relative standard deviations (RSD) for the spiking levels of 0.5 μg L^− 1 in the real samples was 4%, (n = 15).     

Characterisation of River Po particles by sedimentation field-flow fractionation coupled to GFAAS and ICP-MS

A procedure for elemental composition determination of water-borne river particles (Po River) on both size-fractionated and unfractionated submicron particles (0.1–1 μm) by graphite furnace atomic absorption spectroscopy (GFAAS) and inductively coupled plasma-mass spectrometry (ICP-MS) is reported. Sample fractionation was performed using sedimentation field-flow fractionation (SdFFF). The distribution of relative mass vs. particle size was determined using UV detection. Fractions were collected over a narrow size range for scanning electron microscopy. With this combination of techniques the mass, elemental composition, and shape distributions can be obtained across the size spectrum of the sample.

The size distributions of the major elements (Al, Fe) were determined by coupling both GFAAS and ICP-MS techniques to the SdFFF. The procedure was validated using a reference clay sample. Satisfactory agreement was found between both the GFAAS and ICP-MS aluminium signal and the UV detector signal. Some discrepancies were observed in the Fe/Al ratios when comparing GFAAS and ICP-MS. Thus further investigation is in order to fully assess the role of SdFFF-ICP-MS and SdFFF-GFAAS techniques for elemental characterisation of aquatic colloids. Both GFAAS and ICP-MS signals unambiguously indicate a significantly higher Fe content in the lower size range, which is consistent with previous investigations.

Trace element levels in unfractionated Po River particles, determined by both GFAAS and ICP-MS, show good agreement. The high levels of Cu, Pb, Cr and Cd found associated with the colloidal particles underlines the significance of the environmental role played by the suspended matter in rivers in both highly industrialised and intensively cultivated areas.     

The Determination of Arsenic in Soil and Sediment Digests by Graphite Furnace Atomic Absorption Spectrometry

Abstract

A method for the determination of As in siliceous materials from a fluoboric acid matrix by GFAAS is described. The basic analytical procedure also permits the measurement of major, minor and other trace elements by flame or graphite furnace AAS as appropriate. For As analysis, the incorporation of matrix modification with Ni and of corrective measures to overcome interference by Al, Na and Si are discussed. The validity of the method is demonstrated by the accurate analysis of four international standard reference materials and agreement with instrumental neutron activation analysis results for As in environmental samples. One application to the study of As geochemistry in lacustrine sediments is presented.     

Direct determination of germanium in botanical samples by graphite furnace atomic absorption spectrometry with palladium-zirconium as chemical modifier

A method has been described for the direct determination of trace levels of germanium by graphite furnace atomic absorption spectrometry (GFAAS) using chemical matrix modification technique. The stabilization and the pyrolysis temperatures for germanium were investigated with various chemical modifiers including palladium, palladium–magnesium, palladium–strontium and palladium–zirconium. The highest pyrolysis temperature and highest integrated absorbance were obtained using palladium–zirconium modifier, and the severe matrix interference from sulfate can be eliminated. The characteristic mass and absolute detection limit (3σ) of germanium were found to be 16 and 12 pg, respectively. The proposed method was applied to the determination of trace levels of germanium in botanical samples with a recovery range of 92–106%. The hydride generation atomic fluorescence spectrometric (HGAFS) method was employed to analyze the samples and the results agree well with those obtained by GFAAS. The contents of germanium in standard reference materials were determined and the results were in good agreement with the reference values.     

β-Cyclodextrin-Cross-Linked Polymer as Solid Phase Extraction Material Coupled Graphite Furnace Atomic Absorption Spectrometry for Separation/Analysis of Trace Copper

Abstract

The β-cyclodextrin cross-linked polymer (β-CDCP) was synthesized by the reaction of β-cyclodextrin with epichlorohydrin in NaOH and characterized by fourier transform infrared spectroscopy and thermoanalysis. The β-CDCP as a solid phase extraction (SPE) material was used to preconcentrate/separate trace copper using l-(2-pyridylazo)-2-naphthol (PAN) as a complexing agent for Cu-(II)-PAN coupled with a graphite furnace atomic absorption spectrometry (GFAAS) for analysis. The optimized experiment conditions and adsorption capacity were investigated. The detection limit (DL) was 1.11 µg.L^?1 with RSD 4.27% (n = 5, c = 25.0 µg L^?1). The linear range is 6.25–31.25 µg L^?1. Moreover, the β-CDCP could be used repeatedly and offered better a recovery and estimation of trace copper. In order to verify the accuracy of the method, a certified reference water sample was analyzed and the results obtained were in agreement with the certified values. The recovery for copper was 103.6%. The proposed method was applied to the analysis of copper in lake water samples.     

Kinetic Studies of Metal Speciation Using Inductively-Coupled Plasma Mass Spectrometry

Abstract

Kinetic studies of uptake of metal ions by the Chelex batch technique were made to determine Cd, Cu and Pb speciation in model solutions, a snow sample and a river surface water sample. Inductively-coupled plasma mass spectrometry (ICP-MS) and graphite furnace atomic absorption spectrometry (GFAAS) were used for direct determination of these metals. ICP-MS with the solution nebulization technique minimized contamination and adsorption problems involved in the discrete sampling technique of GFAAS, and hence, gave more precise and accurate results. Also, ICP-MS allowed collection of many more data points than GFAAS and was able to resolve components with similar rates of dissociation, which could not always be resolved by GFAAS with its discrete sampling technique. ICP-MS was therefore preferable to GFAAS for kinetic studies of metal speciation. The kinetic data were analyzed by the iterative deconvolution method. The applicability of the Chelex batch technique to metal speciation was validated by analysis of model solutions containing these metal ions with or without EDTA, NTA and fulvic acid. Use of the Chelex batch technique for Cd, Cu and Pb speciation in snow and river surface water samples revealed a number of kinetically distinguishable components of these metals (as complexes) ranging from one to three, probably present as aquo ions or inorganic complexes in the snow sample, and bound to macromolecules/and or colloidal materials in the river surface water sample.     

Determination of trace elements in high purity copper by INAA, GFAAS and ICP/AES

Trace impurity elements in high purity copper metal (4 mine class) put on the market were analyzed by Instrumental Neutron Activation Analysis (INAA) and the results compared with those from Graphite Furnace Atomic Absorption Spectrophotometry (GFAAS) and Inductively Coupled Plasma Atomic Emission Spectrophotometry (ICP-AES). The sample irradiation was done at the irradiation facilities (thermal neutron flux, 5·10¹² n·cm⁻²·s⁻¹) of the TRIGA Mark-III research reactor in the Korea Atomic Energy Research Institute. Four unalloyed copper standards (NIST SRM # 393, 394, 395 and 398) were used to identify the accuracy and precision of the analytical procedure. The homogeneity of samples was assessed by means of the elements such as Ag, As, Co, Sb, Se and Zn. The analytical results of INAA, GFAAS and ICP-AES were in good agreement within expected uncertainties each other and showed the possibility of using them for the analytical quality control.     

Determination of Pt from coke samples by ICP-MS after microwave assisted digestion and microwave assisted cloud point extraction

Platinum in coke samples was determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave-assisted sample digestion and temperature controlled microwave assisted cloud point extraction (MW-CPE). Interferences due to hafnium (¹⁷⁹Hf¹⁶O) were successfully eliminated using MW-CPE with 2-MBT prior to the determination of platinum by ICP-MS. The validity of the method was studied by spike recovery tests and by analyzing certified reference material (BCR-723 street dust). The results obtained for platinum in the BCR-723 were generally in good agreement with the certified values. Furthermore, the preliminary platinum results obtained for coke sample by ICP-MS after MW-CPE were compared to those obtained by a reference method (NiS-Fire Assay preconcentration/Te coprecipitation and ICP-MS determination).     

Determination of Selected Metals in Niger Delta Oils by Graphite Furnace Atomic Absorption Spectrometry

Abstract

Graphite furnace atomic absorption spectroscopic (GFAAS) analysis of oil samples from the onshore and offshore fields in the Niger Delta was carried out in order to determine their trace element contents. The concentrations of the elements (Cr, Co, Cu, Fe, Mn, Ni, Pb, and V) determined ranged from 0.151–941.199 ppb with an average of 30.190 ppb (% RSD<5) for the oil samples analyzed. The pattern of occurrence of each element was in agreement with studies conducted employing neutron activation analysis and flame atomic absorption spectroscopy. From the cluster analysis of the data, two groups of oils were evident. The groups are correlated with each other, indicating common or similar genetic origin. Trace metal parameters indicate that the oils were generated from organic matter of strong terrestrial input. GFAAS proved to be a good method for the analysis of elemental composition and classification of Niger Delta oils.     

Carbon Nanofibers as Solid‐Phase Extraction Adsorbent for the Preconcentration of Trace Rare Earth Elements and Their Determination by Inductively Coupled Plasma Mass Spectrometry

Abstract

Systematic investigations were carried out into the sorption of rare earth elements (REEs) on carbon nonofibers (CNFs) by inductively coupled plasma mass spectrometry (ICP‐MS). The experimental parameters for preconcentration of REEs, such as pH, sample flow rate and volume, eluent concentration, and interfering ions on preconcentration of REEs have been examined in detail. The studied metal ions can be adsorbed quantitatively on CNFs in a pH range from 2.0 to 5.0, and then eluted completely with 0.5 mol l^?1 HNO₃. Based on the above facts, a novel method using a microcolumn packed with carbon nanofibers as an adsorption material was developed for the separation and preconcentration of REEs prior to their determination by ICP‐MS. The proposed method has been successfully applied to the determination of light (La), medium (Eu and Gd) and heavy (Yb) rare earth elements in real sample with the recovery more than 90%. In order to validate this method, two certified reference materials of tea leaves (GBW 07605) and mussel (GBW 08571) were analyzed, and the determined values are in good agreement with the certified values.     

Determination of Lead in Lipstick by Direct Solid Sampling High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry: Comparison of Two Digestion Methods

A new analytical procedure for the determination of lead in lipstick has been developed using direct solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry (SS HR CS GFAAS). The performance of this method has been compared to acid digestion methods for sample preparation, with or without hydrofluoric acid (HF) with inductively coupled plasma mass spectrometry (ICP-MS) detection. Good reliability was obtained for all three methods; the results obtained for certified reference materials with concentrations between 1 and 20 ppm were in agreement with the certified values. However, for materials with complex matrices, such as pearl or Ca-Na borosilicate, only ICP-MS with HF sample digestion or AAS with direct solid sampling allowed complete recovery of lead. To avoid the use of hazardous acids, the development of SS HR CS GFAAS is an interesting alternative. With the AAS method, a characteristic mass of 13.2 pg of lead was obtained, and the limit of detection was 0.005 µg/g. The performance of the method was evaluated by determining lead in lipstick. The use of the solid sampling technique constitutes a good alternative for accurate and rapid determination of lead content in lipstick and cosmetic raw materials, with a suitable limit of detection and a reduced risk of contamination or of analyte loss. Another alternative would be to use ICP-MS determination in conjunction with microwave-assisted acid digestion without the use of HF, which implies accepting a quantification of “nearly total” lead, closer to a “bio-extractible” fraction.     

Method Development for the Speciation of Chromium in River and Industrial Wastewater Using GFAAS

A simple, sensitive and inexpensive method for the speciation of Cr(VI) and Cr(III) in river and industrial wastewater was developed, optimized and validated. Samples were collected, filtered and then chromium species were determined in the filtrate. In the filtrate, total Cr was determined directly by Graphite Furnace Atomic Absorption Spectrometry (GFAAS). A portion of the filtered sample was buffered to pH 6.4, extracted with Amberlite LA-2/MIBK and finally Cr(VI) was determined in the organic extract and Cr(III) in the aqueous phase using GFAAS. The method was evaluated by analysis of the certified reference material, CRM 544, and good accuracy was obtained. The limit of detection for Cr(VI) and Cr(tot)/Cr(III) was found to be 0.30 and 0.08 µg L⁻¹, respectively, and a precision expressed as relative standard deviation of better than 11% was achieved for nine replicates. A number of water samples from the Tinishu Akaki River, Ethiopia, and wastewater samples from a chemical plant in Germany, were analysed. In addition to the GFAAS method, Cr(tot) was also determined using ICP-MS (in CRM 544, lyophilized water, and Tinishu Akaki River water samples) and Cr(tot) and Cr(VI) using UV-VIS spectrophotometry (in CRM 544 and industrial wastewater samples). Good agreement between the different methods was found.     

Oxidability Determination in Waste Waters Using an Automatic Titrator Based on a Multicommutated Unsegmented Flow System

Abstract

The automatic titrator based on a multicommutated unsegmented flow system was applied to redox titrations and used for oxidability determination in waters analysis. This automatic titrator allows the attainment of complete titration curves, being the determination of titrand concentration performed without requiring any prior calibration. After sample treatment (oxidation step), the oxidability determination in waste water samples was accomplished by the automatic flow titrator (titration step). Repeated determinations of standard solutions gave a 3.5% RSD (n=10, 0.010M) for repeatability and a 3.2% RSD (n=2, 0.057M) for reproducibility. Samples results (n=9) were in good agreement (t-test) with those obtained with a reference procedure.     

Clean up Procedures for Determination of Amphetamine in Urine Samples.

ABSTRACT

A comparative study of the main sample preparation techniques used for spectrofluorimetric amphetamine determination in urine is presented. The advantages and disadvantages of three procedures based on liquid-liquid or solid-liquid extraction are tested, and a method for amphetamine determination in presence of methamphetamine and its metabolites is proposed. The results obtained are in agreement with the theoretical contents (spiked samples) or the results provided by a reference (GC) method (r8543161 sample).