Graphite Furnace Atomic Absorption Spectrometry Research Articles

Trace metal concentrations in water and edible tissues of Liza ramada from the Northeastern Moroccan Mediterranean coast: Implications for health risk assessment

This study aims to assess the level of metal contamination (Hg, Pb, and Cd) in water and edible tissues of Liza ramada from the Northeastern Moroccan Mediterranean coast, in order to assess the risk associated with the consumption of this species. 25 specimens of adult L. ramada and water samples were collected at two stations (port of Béni Ansar and Ras Kebdana) during the winter and the summer seasons of 2019. Metal concentrations were determined using graphite furnace and cold vapor atomic absorption spectrometry. Metal concentrations in water showed generally low values, with an order of increasing concentrations of Hg < Cd < Pb. Similarly, metal concentrations in L. ramada muscles showed low values below the guidelines set down by the European Commission Regulation, with an order of increasing concentrations of Cd < Hg < Pb. The calculation of the metal pollution index showed that the fish at the port of Béni Ansar are more contaminated than those at the port of Ras Kebdana. In addition, metal values in the summer are relatively high compared to the winter. Statistical analysis by the student’s t-test for equality of means showed that the effect of the season is more significant on the metals bioaccumulation; moreover, positive correlations were found between Hg–Pb and Pb–Cd in fish muscle. Furthermore, there is a significant positive correlation between metal concentrations and length and weight of L. ramada, except for Cd. L. ramada presented relatively high bioaccumulation factor values, particularly for Hg. The estimation of non-carcinogenic health risks by target hazard quotients (THQ) and maximum safe consumption suggest that these species do not pose a health risk to consumers (THQ < 1), and may be consumed at will, without exceeding 16 kg per week for children.

Exposure to waterpipe smoke and blood heavy metal concentrations

Waterpipe (WP) smoking is a global phenomenon, with the most consumers in Middle East countries and China. Heavy metals exposure related to WP smoking has been associated with many adverse health effects. However, the association of lifestyle factors and smoking habits with blood heavy metals concentration in WP smokers is unclear yet. Therefore, we aimed to investigate the relationship of lifestyle factors (i.e., diet and physical activity) and smoking habits (i.e., duration of the use of WP and times of smoking WP per week) with blood concentrations of lead (Pb) and cadmium (Cd). This cross-sectional study was based on 86 WP smokers in Khalkhal, Iran (2018). Graphite furnace atomic absorption spectrometry (GFAAS) was used to measure heavy metals. The median (interquartile range (IQR)) of Pb and Cd concentrations were 39 (24) and 1.3 (1.2) μg/L. The blood Pb and Cd levels were significantly higher in participants with lower education level (P-value = 0.049 and 0.041, respectively). An IQR increase in physical activity per week was associated with −0.12 μg/L (95% confidence interval (CI): −0.23, −0.01, P-value = 0.04) decrease in Pb concentration. An increase in the times of consuming fruit per week was negatively associated with the concentration of Cd. Overall, our findings suggested that physical activity and healthy diet have been associated with lower blood heavy metal concentrations in WP smokers; however, further studies are needed to confirm these findings.

Effects of Antioxidant Vitamins, Curry Consumption, and Heavy Metal Levels on Metabolic Syndrome with Comorbidities: A Korean Community-Based Cross-Sectional Study.

The burden of metabolic syndrome (MetS) has increased worldwide, especially during the COVID-19 pandemic, and this phenomenon is related to environmental, dietary, and lifestyle risk factors. We aimed to determine the association between the levels of serum heavy metals, hs-CRP, vitamins, and curry intake and to predict risks of MetS based on marginal effects. A data set of 60,256 Koreans aged ≥ 15 years between 2009 and 2017 was used to obtain information on sociodemographic, lifestyle, family history characteristics, MetS, food intake survey, and serum heavy metals. Daily intake of vitamins was measured by a one-day 24 h recall, and curry consumption was calculated using a food frequency questionnaire. Serum heavy metal levels were quantified by graphite furnace atomic absorption spectrometry and using a mercury analyzer. We found that vitamin B1, B2, B3, C, and A intakes were significantly lower in subjects with than without MetS. In contrast, serum levels of Pb, Hg, Cd, vitamin A, E, and hs-CRP were significantly higher in subjects with MetS. The risk of MetS was significantly lower for high curry consumers than low curry consumers (adjusted odds ratio 0.85, 95%CI 0.74–0.98). The risks of MetS were reduced by 12% and 1%, when vitamin B1 and C intakes increased by one mg, respectively, but were increased by 14%, 3%, and 9%, when serum levels of Pb, Hg, and hs-CRP increased by one unit. These results show that the potential health benefits resulting from vitamin and curry intakes could protect the public against the dual burden of communicable and non-communicable diseases. Further studies are required to reduce risk factors associated with serum heavy metal levels and to determine whether interactions between vitamin and curry consumption influence the presence of MetS.

A Study Concerning the Lead Contamination of some Food Products Marketed in Romania During 2017-2019

Lead is a toxic metal that is found in both organic and inorganic forms. The maximum allowed values of lead contamination of foods are established in accordance with European Commission Regulation (EC) No. 1881/2006. The aim of this paper is to follow the dynamics of lead contamination present in various products of non-animal origin. During 2017-2019, various food samples were collected and analysed by graphite furnace atomic absorption spectrometry (GFAAS), to determine lead contamination. The samples came from different counties of the country and from Bucharest. The analysed samples (fruits, wine, vegetables, mushrooms and cereals) show a reduced contamination with lead, compared to the fruit juice samples, although no exceedances of the maximum allowed limits were identified. Following the research, evidence of lead food contamination has been identified, but the average values are within the maximum allowed limits.

Direct Sampling Graphite Furnace Atomic Absorption Spectrometry — A Suitable Tool for the Determination of Metallic Contaminants in Pitch

Abstract Considering the widespread use of pitch as a carbon source for manufacturing of carbon related materials, a method for the determination of Co, Cr, Cu, Mn and Ni in pitch by direct sampling graphite furnace atomic absorption spectrometry (DS-GF AAS) was proposed. The pyrolysis and atomization curves for reference solution and solid sample were evaluated. The influence of sample mass, the use of chemical modifier and the linear calibration range for each analyte were also evaluated. As advantages, the calibration with aqueous reference solutions was feasible for all the analytes and it was possible to use a relatively large sample mass, up to 3 mg directly introduced into the graphite tube. The results obtained by DS-GF AAS were compared with those from analytes determination by inductively coupled plasma mass spectrometry after pitch digestion by microwave-induced combustion and no statistical differences (Student’s t-test) were observed. The proposed method showed some advantages such as the minimum sample handling (only milling), the use of aqueous reference solutions for calibration and contrary to most work using GF AAS, Pd has been evaluated with no chemical modifier required, making the proposed method a suitable alternative for the quality control of pitch.

Estimation of mercury levels in blood by GFAAS after administration of two variants of Shwasakuthara Rasa in human volunteers

Introduction: Mercury is in use as medicine since thousands of years in India. It is the most important raw material of medicines belonging to Rasashastra, a branch of Ayurveda. It is need of time to establish data of pharmacokinetics of mercurial medicines. This is a preliminary study to know the absorption of Shwakakuthara Rasa, a herbo-mineral formulation. Aim: The study drug viz Shwasakuthara Rasa is a complex triturated drug having herbal and mineral ingredients. In this study, bioavailability of mercury from two samples Shwaskuthar Rasa was assessed. Materials and Methods: Shwaskuthar Rasa samples [S 1 and S 2] were manufactured by two formulas from Ayurvedic literature. Ingredients of the formulation are detoxified mercury, detoxified sulfur, detoxified realgar, detoxified borax, detoxified Aconitum ferox Piper nigrum, Piper longum, and Zingiber officinalis. Detoxification of said ingredients was done by specific processes mentioned in Ayurvedic literature. Per cent amount of detoxified mercury is 7.14 % and 11.1 % in S1 and S2 respectively and amount of Piper nigrum is 60% and 22.2 %, respectively. After administration of 125 mg dose of the S1 and S2 to 8 normal volunteers, blood samples were collected at 0, 1, 1.5 and 2 hours. The blood mercury levels were assessed by Graphite Furnace Atomic Absorption Spectroscopy (GFAAS). Results: It is evident that mercury gets absorbed from both formulations. There is difference in absorption pattern. After 2 hours of administration of formulation; mercury level in blood from S1 is significantly higher than S2. Conclusions: The increased absorbance of mercury from S1 can be attributed to much higher levels of P. nigrum in it than S2. Keywords: Ayurveda, Rasashastra, Parad mercury, Shwasakuthara Rasa, Bioavailability, Pharmacokinetics.

Speciation of As(III) and As(V) in Food by Magnetic Dispersive Microsolid Phase Extraction with Dispersive Liquid–Liquid Microextraction with Graphite Furnace Atomic Absorption Spectrometry (GFAAS) Detection

Magnetic dispersive microsolid phase extraction (MDMSPE) was coupled with dispersive liquid–liquid microextraction (DLLME) for the separation and preconcentration of arsenic(V) and arsenic(III) prior to graphite furnace atomic absorption spectrometry detection. In the first step, magnetic ZnFe2O4 nanotubes were employed for adsorbing arsenic(V). The adsorbent was separated from the aqueous phase by the use of an external magnetic field. Next, arsenic(III) in the upper aqueous phase from MDMSPE was enriched by DLLME. Samples were prepared with artificial gastric juice to avoid inter-conversion of the determined species. The parameters affecting the separation and preconcentration of the determined species were optimized. The detection limits of this protocol were determined to be 1.3 and 2.0 pg mL − 1 for arsenic(III) and arsenic(V) with relative standard deviations of 4.5% and 5.6% for a concentration of 1.0 ng mL − 1 (n = 9). The enrichment factors were equal to 175-fold for arsenic(III) and 163-fold for arsenic(V). The developed protocol was employed for the determination of arsenic(III) and arsenic(V) in dairy products without preoxidation or prereduction. The recoveries of spiked samples were from 90.8% to 105%. A milk powder certified reference material was analyzed by this approach and the measured results were in good agreement with the certified value.

Comparing arsenic(V) adsorption by two types of red soil weathered from granite and sandstone in Hunan, China

Different soils have large differences in efficiencies and mechanisms in arsenic (As) adsorption, due to the dissimilarities of soil minerals, organic matter (OM) and physiochemical properties. To understand the differences of As adsorption resulting from these differences among soils, the red soil weathered from granite (RS-G) and sandstone (RS-S) were employed to comparatively study the minerals, OM, physicochemical properties, and the isotherms and kinetics of As(V) adsorption. The soil samples were collected at 0–20 cm depth on the top of the mother rocks in Dingziwan and Yuelu Mountain, Changsha, Hunan province in China. The soil minerals were characterized by X-ray powder diffraction (XRD). The specific surface area (SSA) of the soil samples was determined using a BET Analyzer with nitrogen and multi-point analysis after degassing overnight at 100 °C. The cation exchange capacity (CEC) was determined by the method of ammonium acetate centrifugal exchange, and the OM, pH, and point of zero charge (pHPZC) were measured using improved potassium dichromate volumetric weight method, titration, and potentiometric titration method, respectively. The As(V) in the solution was measured by graphite furnace atomic absorption spectrometry (GFAAS). RS-G contains more clay minerals and iron (hydr)oxides, and less quartz than RS-S by 25.31%, 111.69%, and − 22.39%, respectively. There are similar SSA, CEC, and OM content, but different pHpzc and OM sources between the two soil types. The adsorption experiments reveal (1) the As(V) removal efficiency drops rapidly as the initial As(V) concentration is greater than 4.0 mg/L for RS-G and 8.0 mg/L for RS-S, and that of RS-S decreases more slowly as the As(V) concentration increasing from 4.0 to 20.0 mg/L, (2) the As(V) removal efficiency decreases rapidly as the pH is larger than 8.0 for RS-G and 7.0 for RS-S, and (3) the time reaching equilibrium is 120 min for RS-G and 180 min for RS-S, and their kinetics show two and three stages adsorption processes, respectively. The higher mineral content and pHPZC are the main causes for RS-G showing higher As(V) removal efficiency, shorter time to reach equilibrium, and wider pH range for As(V) adsorption. The young OM in RS-G may be responsible for the rapid decrease of As(V) removal efficiency as the As(V) concentration larger than 4.0 mg/L. Comparatively, the RS-G is more efficient for As(V) adsorption, and is more potential for groundwater protection from As contamination.

Determination of Mn(II) and Mn(VII) in beverage samples using magnetic dispersive micro-solid phase extraction coupled with solidified floating organic drop microextraction followed by graphite furnace atomic absorption spectrometry

Magnetic dispersive micro-solid phase extraction (MDMSPE) was coupled with solidified floating organic drop microextraction (SFODME) for direct separation and preconcentration of Mn(II) and Mn(VII) before graphite furnace atomic absorption spectrometry determination. MDMSPE involved use of magnetic ZnFe2O4 nanotubes for adsorbing Mn(VII). Sorbent was isolated from aqueous phase by an external magnet. Mn(II) in upper solution from MDMSPE was further enriched by SFODME. This method avoids tedious pre-oxidation/pre-reduction operation and time-consuming centrifugation/filtration step. An enrichment factor of 200-fold was obtained. Detection limits of this method were 0.005 and 0.007 ng mL−1 for Mn(II) and Mn(VII) with relative standard deviations of 4.0% and 4.8% (n = 9), respectively. This method was successfully used for detection of Mn(II) and Mn(VII) in tap water, ice tea, energy drink, mineral water, sprite drink and carbonated drink. A certified reference material of water sample was analyzed with satisfactory results. Recoveries of spike experiments ranged from 92.5 to 106%.

In-site and solvent-free exfoliation of porous graphene oxide from pencil lead fiber for solid-phase microextraction of cadmium ion before GF-AAS determination.

Graphene oxide (GO)-functionalized pencil lead fiber was prepared for the first timeby in situ oxidation and exfoliation of graphite contained in pencil lead fiber to porous graphene oxide structure via a one-step solvent-free dielectric barrier discharge (DBD) microplasma treatment. This new fiber was demonstrated as a highly efficient and low-cost solid-phase microextraction (SPME) fiber for the determination of toxic metal ions. The fiber extraction performance was evaluated by using cadmium as a model analyte in a direct immersing SPME mode. Unlike mostcommercially available and other lab-built fibers, the preparation of the graphene oxidized pencil lead fiber is environmentally friendly, low cost, and non-toxic without using any organic solvents. The fiber is robust due to its coating-free configuration. Furthermore, high extraction efficiency and high sensitivity for cadmium can be obtained due to the abundant oxygen-containing functional groups on the surface of the novel fiber. After extraction, the cadmium adsorbed on the fiber was desorbed to 150-μL solution. Graphite furnace atomic absorption spectrometry (GF-AAS) with low sample consumption was used to determine cadmium. The calibration curve for cadmium ions was linear in a range 0.04-0.26μgL-1 with a detection limit of 0.005μgL-1. A relative standard deviation (RSD, n = 5) of 2.1% was obtained at 0.1μgL-1 of cadmium. The sensitivity enhancement factor (EF) value of the proposed SPME method was 25. The SPME fiber was successfully applied to determinecadmium in tap water, river water, and pond water with spike recoveries ranging from 94 to 105%. Pipe network water samples were also analyzed to evaluate the cadmium release to drinking water due to the corrosion of tubes.

Application of polyethylene glycol-coated iron oxide nanoparticles for magnetic solid phase extraction of copper from seawater samples and its determination by graphite furnace atomic absorption spectrometry using response surface methodology for optimization of extraction

In this research, a novel solid phase extraction method combined with graphite furnace atomic absorption spectrometry has been employed for the extraction and trace determination of copper in tap and seawater samples. The technique was based on poly ethylene glycol-coated iron oxide nanoparticle as adsorbent for solid phase extraction of copper ions. Optimal conditions including pH, extraction and desorption time, concentration and volume of eluent, temperature, volume of sample, amount of PEG and sorbent were investigated and optimized using both the one-variable-at-a-time method and response surface methodology. Under the optimal experimental conditions, the calibration graph was linear in range of 0.5–125.0 µg/L with detection limit of 6 ng/L. Good enrichment factor of 121 folds for the analyte was obtained. The repeatability of the method was satisfactory (RSD ≤ 4.8%). Finally a few seawater samples of Chabahar Bay (Southeast Iran) were analyzed successfully with proposed procedure.

Elemental Analysis of Pharmaceutical Products for Chronic Kidney Disease by High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry (HR–CS GFAAS)

Here is reported the development of methods for the determination of Al, Cd, Cu, Mo, and Pb by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR–CS GFAAS) after microwave-assisted acid digestion in pharmaceuticals for patients with chronic kidney disease. The measurements were performed at the primary lines of the analytes. The optimum pyrolysis and atomization temperatures were 1800 and 2700 °C for Al, 600 and 1600 °C for Cd, 1400 and 2200 °C for Cu, 1400 and 2600 °C for Mo and 900, and 2400 °C for Pb, respectively. Palladium was used as a chemical modifier for Pb, while Mg(NO3)2 was employed for Al, Cd, and Cu. The validation parameters (linearity, analytical range, accuracy, precision, limit of quantification, and specificity) were obtained according to the stipulations in the Chapter American Pharmacopeia <233>. The limit of detection was 1.63 μg L−1 for Al, 0.02 μg L−1 for Cd, 0.49 μg L−1 for Cu, 0.76 μg L−1 for Mo, and 0.59 μg L−1 for Pb. The precision was between 2.1% for Mo and 8.1% for Al. The recoveries were from 90.2% for Pb to 106.1% for Cd. The developed methods were successfully applied to determine the five analytes in 50 pharmaceutical formulations. Cadmium, Cu, and Mo concentrations were within the maximum limits recommended by the Brazilian Pharmacopeia in all medicines. However, six drug products had a Pb concentration higher than the limit for this element. All samples analyzed showed relatively high concentrations of Al.

The amino - functionalized magnetic graphene oxide combined with graphite furnace atomic absorption spectrometry for determination of trace inorganic arsenic species in water samples

A novel adsorbent of magnetic graphene oxide (GO) chemically modified by cysteamine hydrochloride (Fe3O4@SiO2/GO-NH2) through thiol-ene click chemistry reaction was synthesized. The prepared Fe3O4@SiO2/GO-NH2 exhibit selective adsorption to As(V) with high adsorption capacity (52.66 mg g−1). Taking Fe3O4@SiO2/GO-NH2 as the adsorbents, a new method of magnetic solid phase extraction (MSPE) combined with graphite furnace atomic absorption spectrometry (GFAAS) was developed in determining trace-level inorganic arsenic species (As(III) and As(V)) in environmental water and bottled water samples. Various experimental parameters affecting the MSPE have been optimized. Under the optimal experimental parameters, the limit of detection of the established method for As(V) was 1.02 ng L−1, the relative standard deviations were 7.9% (intra-day, c = 50 ng L−1, n = 5) and 4.6% (inter-day, c = 50 ng L−1, n = 7), respectively, and the enrichment factor of the method was 392. GBW08666 and GBW08667 (certified reference material) were analyzed to confirm the accuracy of the method, and the results were matched well with the certified values. The established MSPE-GFAAS method was successfully applied in analyzing trace/ultratrace As(III) and As(V) in real water samples.

The measurement and full statistical analysis including Bayesian methods of the aluminium content of infant vaccines

BackgroundAluminium salts are the most common adjuvants in infant vaccines. The aluminium content of a vaccine is provided by the manufacturer and is indicated on the patient information leaflet. There is no independent verification, for example by the European Medicines Agency, of the aluminium content of infant vaccines. MethodsWe have measured the aluminium content of thirteen infant vaccines using microwave-assisted acid and peroxide digestion followed by transversely heated graphite furnace atomic absorption spectrometry. Our data are compared with manufacturer’s data using full statistical analyses including Bayesian methods. ResultsWe found that only three vaccines contained the amount of aluminium indicated by the manufacturer. Six vaccines contained a statistically significant (P < 0.05) greater quantity while four vaccines contained a statistically significant (P < 0.05) lower quantity. The range of content for any single vaccine varied considerably, for example, from 0.172 to 0.602 mg/vaccine for Havrix. ConclusionsThe data have raised specific questions about the significance of the aluminium content of vaccines and identified areas of extremely limited information. Since aluminium is a known toxin in humans and specifically a neurotoxin, its content in vaccines should be accurate and independently monitored to ensure both efficacy and safety.

Heavy Metals Contamination of Urban Soils—A Decade Study in the City of Lisbon, Portugal

There is an intense and continuous growth of the world population living in cities. This increase in population means an increase in car traffic, an increase in new constructions and an increase in the production of waste that translates into an intensive use of land, particularly in terms of soil contaminants. Among other environmental contaminants, toxic metals, such as lead (Pb), cadmium (Cd), nickel (Ni) and chromium (Cr) represent a public health problem. In this study the content of toxic metals in Lisbon’s (Portugal) soils was determined. The study was conducted over approximately a decade in six city locations, with a total of about 700 samples. Each site has different urban characteristics: traffic zone, residential area, urban park and mixed areas. The study allowed to verify the heterogeneity of metal content values in the city soils and their dependence on local traffic. Metal contents were determined by graphite furnace atomic absorption spectroscopy (GFAAS). For each site the geo-accumulation index, pollution factor, degree of contamination, pollution load index and ecological risk factor were calculated. The mean concentrations of Cd, Cr, Ni and Pb in soils were 0.463, 44.0, 46.6 and 5.73 mg/kg of dry soil, respectively. In the last year of the study the values were 0.417, 51.5, 62.4 and 8.49 mg/kg of dry soil, respectively. Cd and Ni exceeded the typical content values of these metals in the earth’s crust, indicating their anthropogenic origin. The correlation analysis revealed a significant correlation between Cr and Ni, Cd and Ni and Cd and Pb contents in the city soils. Regarding the results obtained in this long monitoring campaign, Lisbon’s soils can be considered as having low levels of pollution by these metals.

Complexation reduces nickel toxicity to purple sea urchin embryos (Strongylocentrotus purpuratus), a test of biotic ligand principles in seawater

The potential for Ni toxicity in seawater is of concern because of mining and processing activities in coastal regions. Determining Ni speciation is vital to understanding and predicting Ni toxicity and for bioavailability-based nickel risk assessment. The goal of this study was to characterize the complexation of Ni in relation to toxicity using embryological development of purple sea urchin (S. purpuratus). It was predicted that free ion [Ni2+] would be a better predictor of toxicity than total dissolved Ni concentrations (NiD). Synthetic ligands with known logKf values (Ethylenediaminetetraacetic acid (EDTA), Nitrilotriacetic acid (NTA), tryptophan (TRP), glutamic acid (GA), histidine (HD), and citric acid (CA)) were used to test the assumptions of the biotic ligand model (BLM) for Ni in seawater. [NiD] was measured by graphite furnace atomic absorption spectroscopy (GFAAS) and Ni2+ was first quantified using the ion-exchange technique (IET) and then concentrations were measured by GFAAS; [Ni2+] was also estimated using aquatic geochemistry modelling software (Visual Minteq). The mean EC50 values for [NiD] in unmodified artificial seawater control was 3.6 µM (95% CI 3.0–4.5) [211 µg/L 95% CI 176–264] and the addition of ligands provided protection, up to 6.5-fold higher [NiD] EC50 for EDTA. Compared to the control, measured EC50 values based on total dissolved nickel were higher in the presence of ligands. As predicted by BLM theory, [Ni2+] was a better predictor of Ni toxicity with 17% variability in EDTA and CA media while there was 72% variability in the prediction of Ni toxicity with total dissolved Ni. The results of this research provide support for the application of BLM- based prediction models for estimating Ni impacts in seawater.

Combination of supramolecular solvent-based microextraction and ultrasound-assisted extraction for cadmium determination in flaxseed flour by thermospray flame furnace atomic absorption spectrometry

This study describes the development of a new analytical method for cadmium determination in flaxseed flour based on ultrasound-assisted extraction combined with supramolecular preconcentration followed by thermospray flame furnace atomic absorption spectrometry. Cadmium from flaxseed flour was extracted by ultrasound-assisted radiation in acid medium (1.5 mol L−1HNO3) followed by liquid–liquid microextraction of the acid extractwith dodecanoic acid/THF supramolecular solvent using diethyl dithiophosphate as a chelating agent. The limit of detection and the analytical curve range were found to be 0.10 μg L−1 and 0.35 to 20.0 μg L−1, respectively. The cadmium concentration in the flaxseed flours was ranged from 0.11 ± 0.04 to 0.79 ± 0.03 µg g−1. The proposed methodis considered simpler, faster, low-cost, and environmentally friendly compared to procedures currently used for the determination of cadmium based on acid digestion and using graphite furnace atomic absorption spectrometry and inductively coupled plasma mass spectrometry.

Graphite furnace atomic absorption spectrometric studies for the quantification of trace and ultratrace impurities in the semiconductor grade organic chemicals such as triethylborate, tetraethylorthosilicate and trimethylphosphate

The paper describes the direct determination of impurities by graphite furnace atomic absorption spectrometry (GF AAS) in high (7 N, i.e. 99.99999%) purity organic compounds used as precursors for the deposition of dielectric films by chemical vapour deposition (CVD). The impurity analysis is required to assess the suitability of the compounds that include triethyl borate (TEB), tetraethyl orthosilicate (TEOS) and trimethyl phosphate (TMPO), used as precursors for the deposition of compositionally good quality films. Such features as high sensitivity and limits of detection of GFAAS are exploited for the direct determination of twenty elements (Ag, Al, Bi, Ca, Cd, Cr, Co, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sn, Sb, Zn) in μg L−1 levels in the three compounds. The analysis was preceded by a comprehensive study on the quantitative recovery of spiked elements using clean room procedures. Specially designed sample holders made of polytetrafluoroethylene (PTFE) were used for the analysis. The routinely used polystyrene sample holders are attacked by these chemicals and are thus rendered unsuitable for analysis. GFAAS operating parameters such as drying, pyrolysis and atomisation temperatures were optimized for each analyte in each organic sample for the removal of the matrix effects on the analyte and for quantitative recovery of the analytes. A fourth drying step was introduced in the furnace program. The accuracy of the method has been established by spike recovery tests in the absence of certified reference materials for high purity chemicals. The method is free from any interference and has a precision of <10%. Studies on the effect of polypropylene (PP) and perfluoroalkhoxy (PFA) storage containers on the impurities of these chemicals were performed and the results were discussed. The method can be effectively utilized for the quality control and quality assurance of these important class of chemicals used extensively in semiconductor industry.

Chemometric approach to discrimination and determination of binary mixtures of silver ions and nanoparticles in consumer products by graphite furnace atomic absorption spectrometry

Extensive use of nanomaterials in consumer products inevitably leads to their release to the environment. For monitoring of the fate of nanoparticles in various matrices, low-cost, simple and rapid size-based methods are required. Graphite furnace atomic absorption spectrometry (GFAAS) can be used for this purpose, because due to the difference between a thermal energy required to atomize ionic silver (Ag+) and silver nanoparticles (AgNPs) of different size, the maxima of signals measured by are slightly shifted in time. However, signals are seriously overlapped. Analytical signals of various concentrations of Ag+ and differently sized AgNPs in their mixtures were registered under optimized temperature conditions using GFAAS. The research aim was to develop a procedure for quantitative and qualitative analyses of Ag species in the binary mixtures without the need for the deconvolution of their signals into single components. For evaluation of the qualitative composition of the silver forms present in the studied samples, soft independent modeling of class analogy (SIMCA) was applied. The best results were obtained based on the first derivative of absorption signal. The correct identification rate of the Ag forms was only in the range 25–60% depending on the composition of the tested samples, that indicates limitations of this approach. For estimating the concentrations of the Ag forms, partial least squares regression (PLSR) was implemented. The errors levels (expressed as the root mean squared error of prediction of concentration) for mixtures were acceptable and comparable between the studied databases. The developed model was applied for determination of silver species in personal care products. The errors oscillating up to 7.5% for the sum of Ag species are within the limits of the relative prediction error determined from the research studies while building the model.

Comparison of three common pre-treatment methods for the determination of lead contents by GFAAS in Chinese health-care wines

ABSTRACT Sample pre-treatment plays an important role in sample analysis, which directly affects the accuracy and reliability of the results. In this work we studied the influence of three common sample pre-treatment methods (direct injection, microwave digestion and wet digestion) on the determination of lead (Pb) content of Chinese health-care wines by graphite furnace atomic absorption spectrometry (GFAAS). Six different brands of Chinese health wines were selected for the research. After each Chinese health-care wine was digested by three digestion methods, GFAAS was used to detect the Pb content of the samples. For the selected six different health-care wines, the results showed that the Pb content obtained by GFAAS with different pre-treatment methods were different. Microwave digestion had the best recovery, and was proposed to be applied to the pre-treatment of many kinds of health-care wines, while the direct injection method might be suitable only for health-care wine with lesser amounts of ingredients such as sugar. In the practical work, due to the complexity of the base composition of Chinese health-care wines, currently there is no relevant standard analysis method for the pre-treatment of Chinese health wines. According to the accuracies of the three chosen common pre-treatment methods, it was proposed that microwave digestion might be more suitable as a standard digestion method for the determination of Pb in Chinese health-care wines. This work could provide theoretical support for the further establishment of a standard analytical method for the determination of lead and other (heavy) metal elements in Chinese health wines by GFAAS and other methods.