Air-acetylene Flame Research Articles

DESIGN OF A PORTABLE ELECTROTHERMAL VAPORIZATION FLAME ATOMIC EMISSION SPECTROMETRY DEVICE FOR FIELD ANALYSIS

A nontraditional, portable flame atomic emission spectrometry (FAES) device has been constructed using a welding industry metal cutting torch as the flame source with a tungsten coil electrothermal vaporization device for sample introduction. Twenty-microliter sample aliquots were pipetted onto a commercially available tungsten filament, and a home-written Visual Basic program was used to automatically dry and atomize the sample. The sample was then transported into the heart of the air-acetylene flame, where it was excited, and the resulting emission signal was focused onto the entrance of a miniature charge coupled device spectrometer. Figures of merit were determined for five alkaline and alkali earth metals of biological and environmental significance. Limits of detection were, on average, 100 times lower than those for traditional flame emission spectrometers. The capabilities of this portable device make it an ideal tool for biological field analysis, particularly in areas where traditional laboratories are inaccessible.

Feasibility of high-resolution continuum source molecular absorption spectrometry in flame and furnace for sulphur determination in petroleum products

For the first time, high-resolution molecular absorption spectrometry with a high-intensity xenon lamp as radiation source has been applied for the determination of sulphur in crude oil and petroleum products. The samples were analysed as xylene solutions using vaporisation in acetylene-air flame or in an electrothermally heated graphite furnace. The sensitive rotational lines of the CS molecule, belonging to the ∆ν = 0 vibrational sequence within the electronic transition X 1∑ + → A 1П, were applied. For graphite furnace molecular absorption spectrometry, the Pd + Mg organic modifier was selected. Strong interactions with Pd atoms enable easier decomposition of sulphur-containing compounds, likely through the temporal formation of Pd xS y molecules. At the 258.056 nm line, with the wavelength range covering central pixel ± 5 pixels and with application of interactive background correction, the detection limit was 14 ng in graphite furnace molecular absorption spectrometry and 18 mg kg −1 in flame molecular absorption spectrometry. Meanwhile, application of 2-points background correction found a characteristic mass of 12 ng in graphite furnace molecular absorption spectrometry and a characteristic concentration of 104 mg kg −1 in flame molecular absorption spectrometry. The range of application of the proposed methods turned out to be significantly limited by the properties of the sulphur compounds of interest. In the case of volatile sulphur compounds, which can be present in light petroleum products, severe difficulties were encountered. On the contrary, heavy oils and residues from distillation as well as crude oil could be analysed using both flame and graphite furnace vaporisation. The good accuracy of the proposed methods for these samples was confirmed by their mutual consistency and the results from analysis of reference samples (certified reference materials and home reference materials with sulphur content determined by X-ray fluorescence spectrometry).

Determination of zinc in water samples by flame atomic absorption spectrometry after homogeneous liquid-liquid extraction

In this study, a new and simple homogeneous liquid-liquid extraction (HLLE) method based on a pH-independent phase-separation process was developed using a ternary solvent system [water-tetrabutylammonium ion (TBA+)-chloroform] for the preconcentration of Zn2+ ions. A Schiff’s base ligand was used as the chelating agent prior to Zn2+ ions extraction. Flame atomic absorption spectrophotometry using acetylene-air flame was used for the quantification of analyte after preconcentration. The phase separation occurred due to ion-pair formation of TBA and perchlorate ion. The sedimented phase was then separated using a 100 μL micro-syringe and diluted to 1.0 mL with ethanol. The sample was introduced into the flame by conventional aspiration. After the optimization of complexation and extraction conditions such as pH 9.0, [ligand] = 1.0 × 10−5 M, [TBA+] = 2.0 × 10−2 M, 100.0 μL of [CHCl3] and [CLO4−] = 2.0 × 10−2 M, a preconcentration factor of 100 was achieved for only 10 mL of the sample. The relative standard deviation was 2.3% (n = 10). The limit of detection was sufficiently low and at ppb level. The proposed method was applied to the extraction and determination of Zn2+ in natural water samples with satisfactory results.

Direct Analysis of Dark Honeys for Total Content of Copper and Its Fractionation Forms

Suitability of direct analysis of honey solutions by air–acetylene flame atomic absorption spectrometry for reliable measuring total concentrations of Cu was evaluated and compared with determinations completed after open vessel wet oxidative digestion of honeys with a mixture of HNO3 and H2O2. Total Cu concentrations determined in amber to dark color raw honeys were within 0.95–1.68 mg kg−1. Additionally, solutions of honeys were subjected to fractionation analysis by means of a two-column solid phase extraction procedure with a non-ionic adsorbing resin Amberlite XAD-16 and a strongly acidic cation exchanger Dowex 50W × 8-200. Another set of solutions was subjected to fractionation analysis using ultrafiltration with membranes of molecular weight cut-off size of 100, 50, 30, 10, and 5 kDa. Both approaches used to partition Cu species enabled to obtain information on chemical and physical fractionation patterns. It seems that predominant classes of species (67–94%) are cationic and residual species which could be the most accessible forms of Cu from honey due to very low molecular size and possible association with certain organic compounds.

Speciation analysis of inorganic antimony in airborne particulate matter employing slurry sampling and HG QT AAS

The present paper proposes an analytical procedure for speciation analysis of inorganic antimony in airborne particulate matter using slurry sampling and hydride generation atomic absorption spectrometry (HG QT AAS). During the antimony determination, a quartz T tube cell was heated to approximately 900 °C using air–acetylene flame. The optimization step was performed by employing full two-level factorial and Box–Behnken designs involving the following factors: flow rate and concentration of sodium tetrahydroborate and hydrochloric acid concentration, having as chemometric response absorbance. Using the optimized conditions, the method employing slurry sampling allows for the determination of total Sb and Sb(III) with limits of quantification of 0.3 and 0.2 μg L−1, respectively. The precision, expressed as a relative standard deviation (%RSD), was always lower than 6.2%. The accuracy was confirmed by analysis of a certified reference material of atmospheric particulate matter urban dust furnished by National Institute of Standards & Technology. This method was used to determine total antimony and antimony(III) in four particulate matter samples collected in Bananeira Village, Bahia State, Brazil. In these samples, total antimony concentrations varied from 4.32 to 4.60 ng m−3, and Sb(III) concentrations varied from 0.33 to 0.67 ng m−3.

Concentraciones séricas de vitaminas liposolubles y de zinc en pacientes sometidos a cirugía bariátrica

Introduction Fat-soluble vitamins and zinc are substances not synthesized in the body. Consequently intake of those micronutrients is required. Gastric and biliopancreatic bypass considered malabsorption interventions that can lead to nutritional deficiencies. Material and methods We compared levels of vitamins A and E, zinc and others biochemical markers of 35 controls and 32 patients submitted to bariatric surgery at different times after the operation (after six months, after one year and after more than five years). Vitamins and zinc were determined by HPLC and air-acetylene flame atomic absorption, respectively. Results A mean of 2.15 μmol/L was obtained for controls. In the different times after the surgery, the patients showed decreasing values of vitamin A up to concentrations of 0.63 μmol/L after more than five years after the intervention ( P < .002). For vitamin E, a mean 28.6 nmol/L was obtained for controls, and values between 11.7-15.6 nmol/L for patients at the different times after the surgery ( P < -001). Means of 11.6, 10.7 and 9.9 μmol/L of zinc were observed in patients at the different times, being significantly different from the control group ( P < .001). In addition, we found statistical significance in the concentration of calcium, iron and folic acid. Conclusions Patients after bariatric surgery show absorption problems with a marked lack of nutrients. This fact should be taken into consideration to reduce effects of possible pathologies derived from these deficiencies.

Environmental Risk Assessment in Baghdad City by Determination of Lead Level in Soil Samples

:The concentration of lead has been determined in different sites of Baghdad during summer season 2008.Analysis was carried out using flame atomic absorption spectrophotometer technique (FAAST) at wavelength 217 nm and air-acetylene flame. The lead level was found in a particulate fraction in some soils of AL-Karkh is more than in AL-Rusafsa sites of Baghdad. The levels approach the hazardous limits in most sites as a result of industrial activities and exhaust cars which are very crowded in Baghdad streets.

Determination of Trace Levels of Nickel and Manganese in Soil, Vegetable, and Water

AbstractA simple and reliable method for rapid and selective extraction and determination of trace levels of Ni2+ and Mn2+ was developed by ionic liquid (IL) based dispersive liquid–liquid microextraction coupled to flame atomic absorption spectrometry (FAAS) detection. The proposed method was successfully applied to the preconcentration and determination of nickel and manganese in soil, vegetable, and water samples. After preconcentration, the settled IL‐phase was dissolved in 100 µL of ethanol and aspirated into the FAAS using a home‐made microsample introduction system. Injection of 50 µL of each analyte into an air–acetylene flame provided very sensitive spike‐like and reproducible signals. Effective parameters such as pH, amount of IL, volume of the disperser solvent, concentration of the chelating agent, and effect of salt concentration were inspected by a (25‐1) fractional factorial design to identify the most important parameters and their interactions. Under optimum conditions, preconcentration of 10 mL sample solution permitted the detection of 0.93 µg L−1 Ni2+ and 0.52 µg L−1 Mn2+ with enrichment factors 77.2 and 82.6 for Ni2+ and Mn2+, respectively. The accuracy of the procedure was evaluated by analysis of a certified reference material (CRM TMDW‐500, drinking water).

Research on Lead Levels in Water and Meat Products Produced in the Town of Baia Mare

Samples were processed by atomic absorption spectrometry method, with air acetylene flame and graphite furnace using AAS UNICAM 939 with solar program and ASA 50 PLUS VARIAN, wet digestion method, according to the manual issued by the Romanian Institute for Standardization Bucharest. Values were compared between groups nr.975/1998 then Ministry of Health, Statistical interpretation was performed by Student T-test in Excel program.

Direct analysis of honey for the total content of Zn and its fractionation forms by means of flame atomic absorption spectrometry with solid phase extraction and ultrafiltration approaches

A method of direct analysis of honey by air–acetylene flame atomic absorption spectrometry for reliable determining of the total content of Zn was evaluated and compared with measurements completed after open vessel wet oxidative digestion of honeys with a mixture of HNO 3 and H 2O 2. Applying the proposed method, the concentration of Zn in 13 raw light to dark colour honeys was found to be within 0.26–2.61 μg g −1. Additionally, solutions of selected honeys were subjected to functional speciation analysis using a two-column solid phase extraction with a non-ionic, apolar adsorbing resin Amberlite XAD-16 and a strongly acidic cation exchanger Dowex 50W-x8-200. Another set of solutions was subjected to physical fractionation using filtration with membranes of 0.45 μm pore size and molecular weight cut-off size of 100, 50, 30, 10 and 5 kDa. Both approaches used to partitioning of Zn enabled retrieving information on the fraction of total Zn that is predominant class of species (59–89%) and, regarding its positive charge and very low molecular size, seems to be the most available from honey and absorbable in digestion.

Combination of dispersive liquid–liquid microextraction and flame atomic absorption spectrometry for preconcentration and determination of copper in water samples

A simple and rapid dispersive liquid–liquid microextraction procedure based on an ionic liquid (IL-DLLME) was developed for the determination of trace amounts of copper (Cu 2+) by flame atomic absorption spectrometry (FAAS). In this work, a small amount of an IL 1-hexyl-3-methylimmidazolium bis(trifluormethylsulfonyl)imid ([Hmim][Tf 2N]) as an extraction solvent was dissolved in acetone as a disperser solvent and then the binary solution was rapidly injected by a syringe into the water sample containing Cu 2+, which were complexed by 4,4′-bis(dimethylamino)thiobenzophenone (TMK). After preconcentration, the settled IL-phase was dissolved in 40 μL of ethanol and aspirated into the flame atomic absorption spectrometer (FAAS) using a home-made microsample introduction system. Injection of 50 μL volumes of analyte into an air–acetylene flame provided very sensitive spike-like and reproducible signals. Some important IL-DLLME parameters, such as amount of the ionic liquid, chelating reagent concentration, pH and salt concentration were inspected by a (2 4) full factorial design to identify the most important parameters and their interactions. Under optimum conditions, the calibration graph was linear in the range of 2–50 μg L −1 with a limit of detection of 0.45 μg L −1. The relative standard deviation was 3.3% (n = 5).

Development of a Simple System for the Determination of Arsenic after Hydride Generation Atomic Absorption Spectrophotometry

A simple and inexpensive hydride generation system that uses a pyrex boiling tube as a reduction vessel to hold the acidified sample into which 2cm3 of 100-300mg sodium tetrahydroborate (III) solution isinjected such that the excess molecular hydrogen evolved carries the generated arsine directly through the atomic absorption spectrophotometer nebuliser to a nitrogen-hydrogen entrained air flame for atomic absorption measurement is described. The average absorption by arsenic atoms generated from the total arsine evolved was measured by integrating the absorbance for 16 seconds. The use of the absorption signal integration mode was found to free the technique from most kinetic interferences, while the stripping of the arsine from solution reduces the potential for chemical interferences in the solution phase. Gas flow rates affected sensitivity markedly, but theoptimal flow rates for nitrogen and hydrogen were standardised on 90cm3s-1 and 30cm3s-1 respectively as a compromise between lower flow-rates giving longer arsenic residence times and higher sensitivity, and higher flowrates giving a stiffer, less draught-sensitive flame. An optimum flame height of 6mm above the burner producedsufficient atomization and low background absorption. Generally, sample volumes between 5-20cm3 could be used in different acidic media within the concentration range 10% (v/v) . 50% (v/v). The proposed system produced a significantly improved atomic absorption sensitivity of 25ng and a detection limit of (95% confidence) of 5.2ng forarsenic. Both performance characteristics were found to be better by a factor . 12 and . 27 respectively than achieved with air-acetylene flames. The method is highly reproducible at trace levels having an overall precision of 1% for 0.5ƒÊg of arsenic. The upper limit of linearity of the response for atomic absorption measurements is about 0.7ƒÊg. In use, the apparatus is fast and convenient to operate, enabling about forty determinations per hour

Solid sampling coupled to flame furnace atomic absorption spectrometry for Mn and Ni determination in petroleum coke

A solid sampling flame furnace atomic absorption spectrometry (SS-FF-AAS) system was developed for Mn and Ni determination in petroleum coke. The proposed system for solid sampling was a quartz cell with two perpendicular tubes (T-shaped tubes), positioned above the burner. Manganese and Ni determination was made using an atomic absorption spectrometer with deuterium background corrector, air–acetylene flame and a single slit burner. Powdered samples of coke were introduced as pellets (up to 62 mg) into the quartz cell with a movable hollow quartz piston. When the sample pellet reached the end of quartz cell (T-connection), in the presence of a constant oxygen flow, it quickly burned and the combustion products were transferred to the upper slit tube where the atomic absorption process occurs. Calibration was possible using aqueous reference solutions applied directly on high purity graphite pellets. Results obtained for Mn and Ni using the proposed SS-FF-AAS system were compared to those obtained by inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) after sample decomposition by high pressure microwave assisted acid digestion and also by microwave induced combustion. Agreement better than 96% was obtained for both methods employing a previous step of sample digestion (ICP OES and ICP-MS) and by SS-FF-AAS. Accuracy was evaluated using certified reference materials and also recovery tests. The relative standard deviation was lower than 9% for both analytes. The characteristic mass was 18.3 and 14.7 ng and the limit of detection was 0.6 and 0.8 µg g − 1 for Mn and Ni, respectively. The proposed SS-FF-AAS system can be applied for Mn and Ni determination in petroleum coke, combining a relatively high sample throughput (9 determinations per h), and a suitable precision and accuracy.

An Indirect Atomic Absorption Spectrometric Determination of Trifluoperazine Hydrochloride in Pharmaceutical Formulations Based on Chelate Formation with Palladium(II)

A new application of an indirect atomic absorption spectrometric (AAS) method was offered for the assay of low concentration of trifluoperazine hydrochloride (TFPH) in pure and pharmaceutical dosage form with good accuracy and precision. The method is depended on the formation of metal complex between the drug (TFPH) and palladium(II) to form orange‐yellowish product extractable in organic solvent prior to its aspiration into an air‐acetylene flame and indirectly determined by AAS. Using AA responses, all experimental parameters such as, pH, concentration of palladium, reaction time, extraction time and phase ratio which affect the complexation and extraction of TFPH‐Pd(II), have been investigated. Under optimized conditions, linearity was observed in the range of 0.5‐17 μg mL-1 with detection limit (S/N) of 0.038 μg mL-1, precision in range of 1.18‐1.92%, accuracy as the %Erel of 2.4% and recoveries ranged from 101.7 to 104% with mean value of 102.4±0.135. The proposed method was applied for the determination of TFPH in the drug stelazine by both direct calibration and standard additions procedures and found to be 4.88 and 4.87 mg per unite, respectively compared with the stated value of 5 mg per unite. This method is also compared statistically with direct determination by using UV‐Vis spectrophotometric technique which is preformed in our laboratory and found to be insignificant at 95% confidence level. All statistical calculations were implemented via the chemsoftware Minitab version 11.

High-resolution continuum source molecular absorption spectrometry of nitrogen monoxide and its application for the determination of nitrate

The molecular absorption spectrum of the nitrogen monoxide, NO, produced by a 5% (v/v) nitric acid solution in an air-acetylene flame has been investigated using a simultaneous, high-resolution continuum source spectrometer. The vibrational absorption bands of the electronic transition exhibit very complicated fine structure, and each band consists of a multitude of rotational absorption lines. Some of these lines have been evaluated with regard to their applicability for the determination of nitrate using electrothermal vaporization. A method has been developed, which provides a new way for the determination of nitrate. No spectral interference has been observed, mainly because of the low vaporization temperatures of only 700–900 °C, where no atomization takes place. However, hydrochloric, sulfuric and phosphoric acid, as well as metal salts, which can form acids by hydrolysis, such as Al, Cr, Cu, Fe and Mn, show strong effects and reduce the NO absorption. This kind of interference can be avoided by using a pyrolysis temperature of only 150 °C. Using the NO line 215.360 nm the limit of detection was approximately 5 ng N and the calibration curve was linear at least to 3000 ng N. The method has been validated by analyzing certified reference materials with different nitrate concentrations. The method should also be applicable to the determination of nitrite after oxidizing the nitrite to nitrate and subsequently determining the NO molecular absorption.

Chemical fractionation of Cu, Fe and Mn in canned Polish beers

A dual-column solid-phase extraction (SPE) was applied to study the distribution of Cu, Fe and Mn among the species of different charge and hydrophobicity in canned Polish lager-type beers. In addition, an original open vessel wet digestion method, aimed at decreasing the reagent amounts and the decomposition time, was devised for the determination of the total Cu, Fe and Mn concentrations in the analyzed beers by means of air–acetylene flame atomic absorption spectrometry (F-AAS) and compared with the method of direct beer analysis. To separate distinct Cu, Fe and Mn species, 50-mL portions of degassed beers were passed through a column containing a non-ionic adsorbing resin Amberlite XAD-16, and then the effluents from this column were directly driven through the second column filled with a gel-type strong cation exchange resin Dowex 50W-x4-200. The content of Cu, Fe and Mn was determined in the effluents from both columns, and the eluates from the cation exchanger column achieved by passing 10 mL of a 2 mol L −1 HCl solution through its resin bed. It yielded the discrimination of the phenolic bound, the cationic and the residual species fractions of Cu, Fe and Mn in the beers studied. The results obtained were discussed with reference to the related literature and interpreted concerning possible classes of compounds capable of complexing Cu, Fe and Mn in the beer matrix.

Levels of essential and toxic metals in milk and baked products

Seven essential metals (Ca, Cr, Cu, Fe, Ni, Se and Zn) and two toxic ones Cd and Pb) were determined in milk and some baked products (bread, meat pie and sausages) by atomic absorption spectrophotometry using air-acetylene flame. The mean concentrations (mg/kg, wet matter) were in the following ranges: Ca (29.12 – 7894.45); Zn (2.75 – 18.00); Fe (1.05 – 33.12); Ni (0.75 – 16.82); Cu (0.03 – 0.08); and Pb (0.001 – 0.003). Cadmium, chromium and selenium were below detectable levels. The results are considered generally low in terms of the essential elements except in the cases of Ca and Zn in milk; and Fe and Ni in the baked products. The levels of Cu are too low that none of the food could be considered a good dietary source of the metal. The lead levels are too low in comparison with the standards set by the Food Standards of Australia and New Zealand (FSANZ), indicating that the analyzed samples are not polluted with lead and are safe for human consumption.

Determination of Cd and Pb in medicinal plants using solid sampling flame atomic absorption spectrometry

A procedure for trace determination of Cd and Pb in medicinal samples using solid sampling flame atomic absorption spectrometry (SS-F AAS) was developed for trace determination of Cd and Pb in medicinal plants. Powdered samples were mixed with high purity graphite and introduced as pellets (up to 100 mg) into a quartz device positioned above the burner and heated by air–acetylene flame. Oxygen flowing through the quartz device assure the complete combustion of sample. Combustion was started in 2 s after sample introduction and the produced vapours were subsequently dispersed into the flame. Calibration was performed using different masses of solid certified reference material (for Pb) or with reference solutions applied directly on graphite pellets (for Cd). Integrated absorbance mode was used and signals were integrated in less than 10 s. A deuterium background corrector was used throughout. Characteristic masses were 58 and 790 pg for Cd and Pb, respectively. Accuracy was checked using certified reference materials and the percent relative error was between −7 and 2% for Cd and between −2 and 3% for Pb. Relative standard deviations (repeatability) were always below 10% (n = 5). Limits of detection were 0.012 and 0.10 µg g−1 for Cd and Pb, respectively. The proposed procedure by SS-F AAS is simple and may be applied to conventional atomic spectrometers allowing the determination of Cd or Pb in 40 test samples by hour (excluding the steps for sample preparation).

MINERAL COMPOSITION OF HONEYDEW HONEY PRODUCED IN TRANSYLVANIA DETERMINED BY ATOMIC ABSORPTION SPECTROSCOPY

Contents of Ca, Mg, Fe and Zn of declared honeyde w honey samples from different counties of Transylvania, was determined by atomic absorptio n spectroscopy after dry ashing with air-acetylene flame (Ca, Mg, Fe, Zn). In all studied honeydew honeys, C a was the most abundant of the elements determined, with average concentrations ranging between 54.75-102.6 mg/kg, followed by Mg (52.01-78.4 mg/kg), Fe (3.09-6.27 mg/kg) and Zn (1.54-4.65 mg/kg). These results con firm that Romanian honey can be considered a good source of minerals.

Fractionation of Cd, Cr, Pb and Ni in roadside soils of Uyo, Niger Delta Region: Nigeria using the optimized BCR sequential extraction technique

The optimized BCR sequential extraction procedure was applied to nine roadside soil samples for the determination of Cd, Cr, Pb and Ni. The extractable metals were isolated into three operationally defined fractions viz: acid extractable, reducible and oxidizable. The residue was treated with aqua regia solution. Metal analysis was done using flame atomic absorption spectrophotometry with air–acetylene flame. Results obtained showed the concentrations of the metals as relative abundance in the mobile phases of the samples (based on the sum of the first three fractions) are in the following order: Cd(91.9) > Pb(82.8) > Ni(49.5) > Cr(39.0). The most non-mobilizable metals were Cr and Ni which are generally lithogenic, associated with the silicate matrix, and the order is as follows: Cr(61.0) > Ni(50.5) > Pb(17.2) > Cd(8.1). The recovery of all the metals expressed as the ratio of total metal concentration to fractional sum of the optimized BCR sequential extraction procedure was of the order: Cr(95.6) > Pb(95.0) > Ni(94.8) > Cd(92.4).