Nitrous Oxide-acetylene Flame Research Articles

Determining the Lithium and Calcium Concentrations in Canned Tuna Fish in Iran

Backgrounds and aims: Nutrition is the main way to receive the trace elements that human body needs. Lithium (Li) and calcium (Ca) are two trace elements, which have important roles in human body. There are a few studies about the amounts of calcium and lithium in canned tuna fish. The aim of this study was to determine the concentrations of calcium and lithium in canned tuna fishes. 
 
 Materials and Methods: To this aim, 150 samples of canned tuna fishes from two well-known brands (Majid and Poolak), marketed in Khuzestan province of Iran, were obtained. Li contents of the samples were measured by atomic absorption spectrometry (AAS) with atomization in graphite furnace. Ca contents of the samples were measured by AAS using nitrous oxide-acetylene flame. 
 
 Results: The mean concentrations of calcium in canned tuna fish of Majid and Poolak brands were 448.47 and 398.22 mg/kg, respectively. Additionally, the mean concentrations of lithium in canned tuna fish of Majid and Poolak brands were 38.42 and 39.67 mg/kg, respectively. The mean concentration of calcium in the investigated canned tuna samples fish was lower than provisional tolerable intake (PTI) per day (1000 ppm) set by World Health Organization (WHO) and Environmental Protection Agency (EPA). However, the mean concentration of lithium in the studied canned tuna fish samples was higher than PTI/day (0.650- 3.1 ppm) Set by EPA.
 
 Conclusion: The results of current study showed that the marine food industries need a more-precise and serious monitoring by public health organizations. Additionally, protecting the marine environment from pollutions is an obligation that needs the attention of related organizations and authorities. 

Estudio de la migración de aluminio desde las ollas a la colada de avena

La migración de metales hacia los alimentos es un tema concerniente a la inocuidad alimentaria y la ingesta dietética es una fuente importante de exposición no ocupacional al aluminio. En esta investigación se determinó la cantidad de aluminio que se transfiere desde las ollas al preparar colada de avena con naranjilla (Solanum quitoense), bebida con pH ácido consumida ampliamente en Ecuador. Su preparación se realizó en ollas de aluminio de cinco marcas comercializadas en Quito y durante siete ciclos de cocción. La cuantificación de la concentración de aluminio transferido a las ciento cuarenta muestras de colada se realizó por espectroscopia de absorción atómica con llama de óxido nitroso-acetileno. Las concentraciones de aluminio transferido al alimento durante los siete tratamientos sobrepasan el límite permisible de 1 mg Al/kg establecido por la Unión Europea (Reglamento Europeo UE 1416:2016), excepto para la marca de olla IV que en el séptimo tratamiento presenta 0,76±0,04 mg Al/kg. El análisis de varianza ANOVA de dos factores indica que las marcas de las ollas y el número de tratamientos aplicados sí afecta estadísticamente a la migración de aluminio.

Evaluación de migración de aluminio durante la cocción de arroz blanco en ollas de aluminio

Diariamente en los hogares ecuatorianos se utilizan ollas de aluminio para cocinar, sin saber la cantidad de residuos metálicos que se transfiere a los alimentos. Este trabajo evaluó la migración del aluminio en la cocción de arroz blanco (Oryza sativa L.) en recipientes de este material. Se trabajó con seis tipos de ollas, de diferentes marcas comerciales de mayor presencia en el mercado, en estas se realizó la cocción del alimento por 15 minutos. De cada unidad experimental se tomaron 50,0 gramos de muestra y, luego de secar, se calcinó para obtener cenizas totales que fueron sometidas a un proceso de digestión ácida. La cuantificación de aluminio se realizó mediante la técnica de absorción atómica con llama de óxido nitroso–acetileno. Se realizaron cinco ciclos de trabajo secuenciales con cada recipiente, los resultados obtenidos se compararon con el límite máximo permisible de 1 mg Al/kg de alimento establecido por la OMS y la Unión Europea. Se pudo observar que luego de la tercera cocción, la migración de aluminio baja hasta valores inferiores al límite máximo permisible excepto en una de las muestras. El estudio permite concluir que la migración de este metal va disminuyendo con el número de usos en las condiciones experimentales descritas.

Application of Internal Standard Method for Several 3d-Transition Metallic Elements in Flame Atomic Absorption Spectrometry Using a Multi-wavelength High-resolution Spectrometer.

We investigated a simultaneous internal standard method in flame atomic absorption spectrometry (FAAS), in order to better the analytical precision of 3d-transition metals contained in steel materials. For this purpose, a new spectrometer system for FAAS, comprising a bright xenon lamp as the primary radiation source and a high-resolution Echelle monochromator, was employed to measure several absorption lines at a wavelength width of ca. 0.3 nm at the same time, which enables the absorbances of an analytical line and also an internal standard line to be estimated. In considering several criteria for selecting an internal standard element and the absorption line, it could be suggested that platinum-group elements: ruthenium, rhodium, or palladium, were suitable for an internal standard element to determine the 3d-transition metal elements, such as titanium, iron, and nickel, by measuring an appropriate pair of these absorption lines simultaneously. Several variances of the absorption signal, such as a variation in aspirated amounts of sample solution and a short-period drift of the primary light source, would be corrected and thus reduced, when the absorbance ratio of the analytical line to the internal standard line was measured. In Ti-Pd, Ni-Rh, and Fe-Ru systems chosen as typical test samples, the repeatability of the signal respnses was investigated with/without the internal standard method, resulting in better precision when the internal standard method was applied in the FAAS with a nitrous oxide-acetylene flame rather than an air-acetylene flame.

Ultrasonic assisted ionic liquid based microextraction for preconcentration and determination of aluminum in drinking water, blood and urine samples of kidney failure patients: Multivariate study

We have developed a simple ultrasonic-assisted ionic liquid-based microextraction (US-ILME) method for trace levels of aluminum (Al3+), in water, blood, and urine samples, followed by atomic absorption spectrometry with a nitrous oxide–acetylene flame. An ionic liquid, 1-hexylpyridinium hexafluorophosphate [Hpy][PF6], was used as the extraction solvent, and 8-hydroxyquinoline (oxine), was used as the Al3+ chelating agent. A multivariate strategy was employed to evaluate five factors/variables (concentration of the chelating agent, pH, amount of ionic liquid, sonication time and centrifugation time) at once, whereas a central composite design was used to find the optimum values of the significant variables. The multivariate strategy was used to estimate the optimum values of experimental factors that influence the efficiency of US-ILME. Under the optimum experimental conditions, the limit of detection (3 s) and enrichment factor were 0.66 μg L−1 and 113, respectively. The relative standard deviation (RSD) for six replicate determinations of 10 μg L−1 of Al3+ was 1.7%. The method was validated by the analysis of certified reference materials and applied successfully to the determination of Al3+ in different types of drinking water, and in blood and urine samples of kidney failure patients. The data indicated that the levels of Al3+ were significantly higher in kidney failure patients compared with healthy referents (p < 0.01).

Evaluación analítica para la determinación de aluminio, bario y cromo en aguas, por espectroscopia de absorción atómica con llama óxido nitroso-acetileno

La meta de un análisis químico de aguas es generar resultados correctos y confiables; la validación de ensayos es uno de los aspectos más importantes para conseguir este propósito. Además, constituye un factor clave para la prestación de servicios analíticos. La Espectroscopia de Absorción Atómica con Llama Óxido Nitroso-Acetileno es una de las metodologías más propicias y ventajosas para la cuantificación de metales en aguas; para su comprobación, se halló la precisión y exactitud para las determinaciones de aluminio, bario y cromo. El objetivo fue confirmar la aplicación correcta del método para el análisis de aguas. Se trabajaron muestras de agua de diferente procedencia, siguiendo estrictamente los protocolos de verificación. Se encontraron resultados satisfactorios en precisión y exactitud con el fin de emitir resultados confiables y reales de la muestra analizada. La determinación de ion sulfato en aguas es una de las metodologías analíticas más discutidas que se conoce en el ámbito científico técnico del análisis de aguas, principalmente por las desventajas que presentan los métodos aceptados internacionalmente (gravimétrico, turbidimétrico y cromatográfico).

Method development for the determination of fluorine in toothpaste via molecular absorption of aluminum mono fluoride using a high-resolution continuum source nitrous oxide/acetylene flame atomic absorption spectrophotometer

Fluorine was determined via the rotational molecular absorption line of aluminum mono fluoride (AlF) generated in C2H2/N2O flame at 227.4613nm using a high-resolution continuum source flame atomic absorption spectrophotometer (HR-CS-FAAS). The effects of AlF wavelength, burner height, fuel rate (C2H2/N2O) and amount of Al on the accuracy, precision and sensitivity were investigated and optimized. The Al–F absorption band at 227.4613nm was found to be the most suitable analytical line with respect to sensitivity and spectral interferences. Maximum sensitivity and a good linearity were obtained in acetylene-nitrous oxide flame at a flow rate of 210Lh−1 and a burner height of 8mm using 3000mgL−1 of Al for 10–1000mgL−1of F. The accuracy and precision of the method were tested by analyzing spiked samples and waste water certified reference material. The results were in good agreement with the certified and spiked amounts as well as the precision of several days during this study was satisfactory (RSD<10%). The limit of detection and characteristic concentration of the method were 5.5mgL−1 and 72.8mgL−1, respectively. Finally, the fluorine concentrations in several toothpaste samples were determined. The results found and given by the producers were not significantly different. The method was simple, fast, accurate and sensitive.

Germanium determination by flame atomic absorption spectrometry: An increased vapor pressure-chloride generation system

A new chloride generation system was designed for the direct, sensitive, rapid and accurate determination of the total germanium in complex matrices. It was aimed to improve the detection limit of chloride generation technique by increasing the vapor pressure of germanium tetrachloride (GeCl 4). In order to do so, a novel joint vapor production and gas–liquid separation unit equipped with a home-made oven was incorporated to an ordinary nitrous oxide–acetylene flame atomic absorption spectrometer. Several variables such as reaction time, temperature and acid concentration have been investigated. The linear range for germanium determination was 0.1–10 ng mL −1 for 1 mL sampling volume with a detection limit (3 s) of 0.01 ng mL −1. The relative standard deviation (RSD) was 2.4% for nine replicates of a 1 ng mL −1 germanium solution. The method was validated by the analysis of one non-certified and two certified geochemical reference materials, respectively, CRM GSJ-JR-2 (Rhyolite), and GSJ-JR-1 (Rhyolite), and GBW 07107 (Chinese Rock). Selectivity of the method was investigated for Cd 2+, Co 2+, Cu 2+, Fe 3+, Ga 3+, Hg 2+, Ni 2+, Pb 2+, Sn 2+, and Zn 2+ ions and ionic species of As(III), Sb(III), Te(IV), and Se(IV).

A novel rapid method for preparation of sample solution for chemical characterisation of titanium minerals by atomic spectrometry

A new rapid decomposition and dissolution method with a mixture of sodium di-hydrogen orthophosphate and di-sodium hydrogen orthophosphate as a novel flux is described. The minerals are fused with (1:1) mixture of the above salts (flux) and the melt is dissolved in distilled water. The solution is diluted to desired volume depending on the instrumental technique used for determination. ICP-OES is used for the determination of Al, Ca, Mg, Cr, V, Si, Fe and Ti without interference from titanium, iron and sodium phosphate (introduced as flux). All the elements except Si and V are also determined by AAS. The use of nitrous oxide–acetylene flame eliminates the depression due to titanium in the measurement of Mg, Mn, Cr and Fe in air–acetylene flame. Synthetic mixture conforming to ilmenite and rutile composition are analyzed by ICP-OES and AAS to check the validity of the method. The results are in good agreement. The proposed method has been applied to natural samples and the results are evaluated against the established decomposition method using potassium bisulphate. Both ICP-OES and AAS yielded comparable results. The R.S.D. of the proposed method in case of ICP-OES varies from 0.5 to 2%, whereas for AAS it varies from 1.5 to 3% for different elements ( n = 5). The novelty of the proposed sample decomposition lies in its simplicity, ease and speed of fusion with minimal skills besides being eco-friendly unlike the reported tedious complicated decomposition procedures involving variety of fluxes and lot of hazardous chemicals.

Influence of acid mining activity on release of aluminium to the environment

An optimized BCR three-step sequential extraction procedure, several single extractions and the reactive aluminium determination after chelating ion-exchange on Iontosorb Salicyl were used for the fractionation of Al in soil samples from a mining area with sulphidic deposits. The aluminium amounts released by used extraction procedures were valuated and discussed. The new indicative values of fractional Al concentrations in five Chinese certified reference materials (GBW 07103, 07304, 07401, 07405, 07407) were determined after Al fractionation by optimized BCR three-step sequential extraction procedure. The aluminium toxicity indexes calculated for two different soil extracts and plant samples were used for assessment of Al toxicity to plants. It can be concluded that the most sensitive indicator of increasing aluminium toxicity to plants is determination of reactive Al species in soil solution by chelating ion-exchange solid phase extraction. The atomic absorption spectrometry with nitrous oxide-acetylene flame was used for determination of total Al amounts and the Al concentration in different extraction fractions as well.

Sistema TS-FF-AAS com chama acetileno-ar como alternativa em relação à chama acetileno-óxido nitroso em FAAS na determinação de estanho

Este trabalho propõe o desenvolvimento de um procedimento analítico para a determinação em linha de estanho em soluções analíticas empregando a técnica de espectrometria de absorção atômica com nebulização térmica em tubo metálico aquecido na chama (TS-FF-AAS) como alternativa ao uso da chama de óxido nitroso-acetileno em espectrometria de absorção atômica, cujo comburente apresenta um custo elevado frente ao ar comprimido. Foram avaliados parâmetros para a otimização do sistema, tais como: vazão do carregador (ar), volume de amostra injetada e concentração do ácido (HCl). Foi construída curva analítica linear [A= -0,00163 + 0,00319 [Sn], (r= 0,9998)] no intervalo de 10 a 80 mg Sn L-1. O limite de detecção, o desvio padrão relativo (n=12) e a freqüência analítica foram: 1,7 mg L-1 Sn, £ 2,7% and 120 h-1 respectivamente. O sistema TS-FF-AAS é uma alternativa para a determinação de Sn.

Analysis of yttrium aluminium borate crystals by solution-based methods: inductively coupled plasma atomic emission spectrometry and flame atomic absorption spectrometry

Comparative analysis of yttrium aluminium borate (YAB) /YAl 3(BO 3) 4/ optical single crystals was performed by flame atomic absorption spectrometry (FAAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) methods for Cr, Dy, Er, Yb, Y, Al, B and Mo. The dopant element, Ce, could be determined only by the ICP-AES method at the required concentration level. The powdered crystal samples were fused with lithium metaborate (LiBO 2) at 950 °C in a platinum crucible and then dissolved in 6 mol l −1 HCl. Although this fusion-dissolution procedure proved to be simple and effective, the quantitative determination of B—as the matrix element in samples—was handicapped by the B content of the fusing reagent. For the FAAS method, with the use of nitrous oxide–acetylene flame, cesium chloride ionization buffer and lanthanum chloride releasing agent [0.1+0.2% (m/v), respectively] were applied. These agents enhanced the atomic absorption signals of Cr, Dy, Er, Mo, Yb and Y, whereas no change of sensitivity was resulted in for Al and B. A fairly good agreement was found between the results of the two alternative spectrochemical methods. The predicted stoichiometry of the crystals was also well approximated indicating the reliability of the crystal growth technology applied.

Determination of Calcium in Cereal with Flame Atomic Absorption Spectroscopy. An Experiment for a Quantitative Methods of Analysis Course

This article describes the determination of calcium in cereal with flame atomic absorption spectroscopy. A cereal sample is crushed then dry-ashed at 600 °C in a silica crucible. The residue is treated with 5 mL of 6 M hydrochloric acid, diluted to volume, and aliquots taken and prepared for analysis using the two increment standard addition approach. The prepared solutions are aspirated into a nitrous oxide–acetylene flame and the absorbance measurements are made using the resonance line of calcium at λ = 422.7 nm, 0.5-nm slit width, and 5.0-mA lamp current. This experiment has been successfully used in the Quantitative Methods of Analysis course. It minimizes hazardous waste by eliminating the need for sample digestion with concentrated nitric acid. The results obtained by 36 students majoring in biochemistry, biology, chemistry, Earth science, or environmental science are presented. The results for the determination of calcium in two brands of cereal showed good precision with the majority (72%) of the...

Fate of vanadium determined by nitrous oxide–acetylene flame atomic absorption spectrometry in unburned and burned Venezuelan crude oil

The use of nitrous oxide–acetylene flame atomic absorption spectrometry for the determination of vanadium in burned and unburned Venezuelan crude oil was demonstrated. Results from laboratory controlled experiments suggest that if the temperature typically obtained in the burning of oil as a form of re-mediation (∼1000 °C), then vanadium will not be removed from burning crude oil. This was found to be the case in an open container, on the surface of water, and on the surface of a fixed size sandy soil.

Content of strontium, lithium and calcium in selected milk products and in some marine smoked fish

The strontium, lithium and calcium contents have been determined in 87 samples of five kinds of milk-fermented products, as well as in 93 samples of ten kinds of marine smoked fish. The samples were purchased on the local market. The representative samples were dry ashed in quartz crucibles and the ash was treated with suitable amounts of conc. HCl and a few drops of conc. HNO3. The obtained sample solution was then used for the determination of Sr, Li and Ca by the flame atomic absorption spectrometry (AAS) method. Ca and Li were determined using the air-acetylene flame and Sr with nitrous oxide-acetylene flame, according to the manufacturer's recommendations. The contents of Sr in the fermented milk products ranged from 0.21 to 0.79 (mean 0.44 +/- 0.07) and in the marine smoked fish from 0.02 to 4.63 (mean 1.16 +/- 0.24) mg/kg of the edible form of both products. Li contents in the milk products ranged from 0.01 to 0.50 (mean 0.07 +/- 0.04) and in the smoked fish from 0.00 to 0.58 (mean 0.11 +/- 0.08) mg/kg. The calcium was highest in the milk products and ranged from 1,010 to 2,020.0 (mean 1,377 +/- 143) mg/kg. In the smoked fish calcium varied strongly and ranged from 40 to 1,052 (mean 303 +/- 53) mg/kg of the edible form. The calculated average ratio of strontium to calcium (mg Sr/1 g Ca) in the milk beverages and yogurts amounted 0.32 and in the smoked fish was 12 times as high and amounted 3.84. The main purpose of this work was to present Ca, Sr and Li together. This is justified because Sr and to some extent also Li are able to modulate Ca metabolism and vice versa.

Determination of calcium, magnesium and strontium in soils by flow injection flame atomic absorption spectrometry

Several procedures for the determination of Ca, Mg and Sr in soils have been compared on the basis of the accuracy of analysis of two NIST reference materials (Montana Soils SRM 2710 and SRM 2711). Samples were dissolved in a mixture of hydrofluoric and nitric acids in sealed vessels in a microwave oven and in teflon beakers on a hot plate. The digests obtained from both dissolution methods were evaporated to dryness in an attempt to remove silicon. Boric acid was added to prevent the precipitation of the lanthanum releasing agent (as lanthanum fluoride) and potassium was added as an ionization buffer. Determinations were made by flame atomic absorption spectrometry with both the nitrous oxide–acetylene flame and the air–acetylene flame, with calibration either by standard additions or against external standards matrix matched with respect to nitric acid, boric acid, lanthanum and potassium. The silicon remaining in the solution was also determined by external calibration. A single-line flow injection manifold was used to overcome any problems due to the presence of high dissolved solids. A volume of 300 μl was injected into a water carrier stream flowing at 8 ml min −1. To determine Ca in the air–acetylene flame, it was necessary to remove silicon. Magnesium was determined in either flame without complete removal of the silicon, however, for the determination of Sr, it was necessary to remove the silicon and use the nitrous oxide–acetylene flame. The indicative value for Sr in SRM 2710 was too low: the value determined was 360±30 μg g −1.

The development of the nitrous oxide-acetylene flame for atomic absorption spectroscopy -- a personal account

The development of the nitrous oxide-acetylene flame for atomic absorption spectroscopy -- a personal account

Extractable chromium determination in soils by AAS

The lixiviation of trace metals from soils using selective extractants gives valuable information, especially for agricultural purposes. The two reagents validated by a group of European researchers coordinated by the Measurements and Testing Program (MAT) of the Commission of the European Community, in single extraction procedures, are EDTA 0.05 moll−1 and CH3COOH 0.43 moll−1. This paper reports the effect of these extractants upon chromium determination in extracts by AAS. Matrix effects were studied in extracts of two soils of different origin: a terra rossa soil from a Mediterranean area and a sewage amended soil. For the FAAS technique, the matrix effects were studied for air-acetylene and nitrous oxide-acetylene flames and using Cr(VI) and Cr(III) as standard solutions. The interfering effects observed are circumvented by the use of 1% 8-hydroxyquinoline as suppressor agent. For the ETAAS technique, charring and atomization curves were obtained for extracts in each reagent and after setting up the graphite furnace program, matrix effects were studied. Different matrix modifiers (Mg(NO3)2, Pd and Triton X-100) were also tested. Once the analytical method had been established, single extraction procedures were applied in the two soils, determining the percentage of extractable chromium in relation to the total content.

Determination of total chromium in sediments by FAAS

The determination of chromium by flame atomic absorption spectroscopy (FAAS), e.g. as performed for environmental matrices, is still a controversial matter as can be concluded from a literature review. Most controversy is due to the measurement conditions or the effect of the interferences; other conditions such as digestion seem to be less critical. Consequently, this paper reports a systematic study of the instrumental settings for the two flame modes that are most widely used: air-acetylene and nitrous oxide-acetylene. In connection with the study of experimental conditions, possible interferences are investigated involving nineteen cations and some anions in different ratios Cr:interferent. Different releasers to overcome interferences are considered. The results are critically compared with current literature. For the operational conditions the quality parameters such as the linear range, detection limits, precision and accuracy are established. Although the nitrous oxide-acetylene flame is mostly recommended, this study reveals that a better choice can be the use of a fuel-rich air-acetylene flame with the addition of 1% 8-hydroxyquinoline (oxine) as protective agent. The method is applied to and validated by four sediment certified reference materials.

Atomic absorption spectroscopic determination of molybdenum in aqueous tetrathiomolybdate solutions

The flame atomic absorption spectroscopic determination of molybdenum, in aqueous solutions of tetrathiomolybdate (MoS 4 2− , TTM) and paramolybdate species (Mo7O 24 2− , PM) has been investigated. A serious signal decrease occurred, if molybdenum has been present as tetrathiomolybdate species, and the sensitivity loss has been 85%. To improve the sensitivity, the solutions of TTM have been digested by wet-acid treatment, and made 0.14 mol·l−1 ammonia. Finally, Mo has been determined by AAS using a nitrous oxide-acetylene flame. The range of the calibration was 0–100 mg·l−1 and the relative standard deviation of the slope was less than 1%.