Molecular species in the flame may absorb strongly. Molecular absorption is most common at wavelengths below about 350 nm. To check for non-atomicabsorption at the barium wavelength use the following procedure. Since the deuterium lamp is not effective at the 553.6 nm line, an alternative source may be used, i.e., a molybdenum lamp at the nearby line of 553.3 nm can act as a continuum source to measure the non-atomic absorbance. The non-atomic signal is then subtracted from the apparent absorbance of the sample and standard solutions, as measured at the normal 553.6 nm barium line.
In this work a flow-injection system was developed for the direct determination of calcium in milk by flameatomicabsorptionspectrometry. The potentiality of a flow- injection system employing a simultaneous injection of sample and lanthanum in a merging zone approach was evaluated. Besides dilution in water, other sample pre-treatment procedures were studied for comparative purposes such as dilution in acid, and sample decomposition in a microwave oven system using diluted or concentrated acids.
developed for the single-step extraction and preconcentration of lead and copper in tobacco samples. Transmission electron microscopy and X-ray diffraction spectrometry were used to characterize the adsorbent. The experimental parameters affecting extraction efficiency, including amount of nanoparticles, volume of chelating reagents, sample pH, ultrasonic time and desorption conditions were investigated. The analytes desorbed from nanoparticles were determined by flameatomicabsorptionspectrometry. Under the optimum conditions, good linearity was obtained in the range of 2-400 µg L -1 for copper and 5-800 µg L -1 for lead (r > 0.998, p < 0.05). The limits of detection
Methods which have been applied to the determination of Lead are atomicabsorption (Larsen and Ludwigsen, 1997), Emission spectroscopy (Yoakum et al., 1975) and colorimetry are subject to series interferences. Hydride Generation combined with AtomicAbsorption Spectrometric (HG-AAS) is a well developed technique can be used for the determination of volatile hydride-forming elements such as arsenic, selenium, antimony and others at trace levels (Dedina and Tsalev, 1995). The advantages of hydride generation atomicabsorptionspectrometry over other atomicabsorption spectrometric techniques such as the flame and graphite furnace methods are increased atomization efficiency, higher selectivity because the analyte is
For the determination of metals in any organic matrix such as plants and propolis, the samples isrt have to be mineralized. Various mineralization process have already been described for different matrices, such as alcohol, alcoholic beverage, honey, beeswax, food, vegetables and seeds (Campos & Limaverde Filho, 1996; Gonzáles et al., 1999; Okada et al., 1997). Cadmium, chromium and lead have been determined in bee products (including raw products) by atomicabsorptionspectrometry with a graphite oven (Conti & Botrè, 2001). However, a procedure of mineralization for the hydroethanolic extract of propolis has not yet been published..
USE OF SLURRY SAMPLING IN THE DETERMINATION OF Cu AND Zn IN ANTARCTIC LIMPETS AND Ni IN RIVER SEDIMENT BY FLAMEATOMICABSORPTIONSPECTROMETRY. In order to demonstrate the feasibility of slurry sampling for environmental studies, different methodologies were developed for Cu and Zn in antarctic limpets and Ni in river sediment with FAAS detection. Studies focusing particle size, acid concentration, slurry stability, selectivity, among others were carried out in order to define the better conditions for slurry analysis. A study related to the depth profile for Ni in the Atibaia River sediment was made after optimization conditions for this element. For accuracy check, certified reference material was used as well as decomposition with microwave oven.
ON-LINE ANODIC ELECTRODISSOLUTION SYSTEM FOR DIRECT DETERMINATION OF METALLIC ALLOYS BY ATOMICABSORPTIONSPECTROMETRY. An automatic system for the direct determination of lead and tin by atomicabsorptionspectrometry is described. The on- line treatment of the metallic samples was obtained by anodic electrodissolution in a flow injection system. Lead was determined by flameatomicabsorptionspectrometry (FAAS) and tin by graph- ite furnace atomicabsorptionspectrometry (GFAAS). A computer program managed the current source and the solenoid valves that direct the fluids. Good linear correlations between absorbance and current intensity for lead and tin were observed. Results were in agreement with the certified values. Precision was always better than 5%. The recommended procedure allows the direct deter- mination of 60 or 30 elements/h using FAAS or GFAAS, respectively.
EVALUATION OF MINERAL COMPOSITION OF TEA FROM SENESCENT LEAF OF Montrichardia linifera (Arruda) Schott (Araceae) BY FLAMEATOMICABSORPTIONSPECTROMETRY (FAAS). Levels of Ca, Mg, Fe, Zn, Cu and Mn were determinated by FAAS in the tea and dry matter from senescent leaf from Montrichardia linifera, plant used in folk medicine Amazon. The content of these metals that are transferred of the leaf to the infusions have presented signiicant reductions, however, the Mn values in the infusion may exceed the tolerable daily intake (11 mg) if consumption of this tea is greater than 1.0 L per day. So the tea of senescent leaves of M. linifera may be considered as a toxic beverage and thus its use is not advised.
DEVELOPMENT OF AN ANALYTICAL METHOD FOR THE DETERMINATION OF HEXAVALENT CHROMIUM IN WATER SAMPLES BASED ON LIQUID-LIQUID MICROEXTRACTION WITH DETECTION BY FLAMEATOMICABSORPTIONSPECTROMETRY. In this study, a method for determination of hexavalent chromium in aqueous samples using liquid-liquid microextraction (LLME) and detection by FlameAtomicAbsorptionSpectrometry (F AAS) was developed. The LLME procedure was based on the extraction of Cr (VI) by acetone at a sample pH of 1.2. The use of saturated ammonium sulphate solution allowed effective separation of the aqueous and organic phases and acetone extracted chromium. The sample pH, acetone volume and stirring time were optimized by a full factorial design.
The present paper proposes an on-line pre-concentration system for cadmium determination in drinking water using flameatomicabsorptionspectrometry (FAAS). Cadmium(II) ions are retained as 1-(2-pyridylazo)-2-naphthol (PAN) complex at the walls of a knotted reactor, followed of elution using hydrochloric acid solution. The optimization was performed in two steps using factorial design for preliminary evaluation and a Box–Behnken design for determination of the critical experimental conditions. The variables involved were: sampling flow-rate, reagent concentration, pH and buffer concentration, and as response the analytical signal (absorbance). The validation process was performed considering the parameters: linearity and other characteristics of the calibration curve, analytical features of on-line pre-concentration system, precision, effect of other ions in the pre-concentration system and accuracy. Using the optimized experimental conditions, the procedure allows cadmium determination with a detection limit (3 j / S) of 0.10 Ag L ÿ 1 , a quantification limit (10 j / S) of 0.33 Ag L ÿ1 , and a precision, calculated as relative standard deviation (RSD) of 2.7% (n = 7) and 2.4% (n = 7) for cadmium concentrations of 5 and 25 Ag L ÿ 1 , respectively. A pre-concentration factor of 18 and a sampling frequency of 48 h ÿ1 were obtained. The recovery for cadmium in the presence of several ions demonstrated that this procedure could be applied for the analysis of water samples. The method was applied for cadmium determination in drinking water samples collected in Salvador City, Brazil. The cadmium concentrations found in five samples were lower than the maximum permissible levels established by the World Health Organization.
ELECTROCHEMICAL HYDRIDE GENERATION FOR SELENIUM DETERMINATION IN A FLOW INJECTION SYSTEM WITH AIR-GLP FLAMEATOMICABSORPTION SPECTROMET- RIC DETECTION. This paper presents a system for electrochemical hydride generation using flow-injection and atomicabsorptionspectrometry to determine selenium in biological materials. The electrolytic cell was constructed by assembling two reservoirs, one for the sample and the other for the electrolytic solution separated by a Nafion membrane. Each compartment had a Pt electrode. The sample and electrolyte flow-rates, acidic media, and applied current were adjusted to attain the best analytical performance and ensure the membrane lifetime. The atomisation sys- tem used a T quartz tube in an air-LPG flame. The composition of the flame, the observation height, and the argon flow rate used to carry the hydrides were critically investigated. The system allowed to perform thirty determinations per hour with a detection limit of 10 µ g L -1 of Se. Rela-
DETERMINATION OF Mn, Cu AND Zn IN SALINE MATRICES BY FLAMEATOMICABSORPTIONSPECTROMETRY AFTER SEPARATION AND PRECONCENTRATION ON AMBERLITE XAD-7 IMPREGNATED WITH ALIZARIN RED S. The aim of this work was to explore the possibility of the application of a non-ionic resin obtained by impregnation of Alizarin Red S (VAS) in Amberlite XAD-7 for manganese, copper and zinc separation and preconcentration in saline matrices. For these system, the metals were quantitatively retained, in the pH range 8.5-10.0, by using 0.50 g of solid phase, stirring time of five minutes and a total mass up to 200 µg of each cation. The sorbed elements were subsequently eluted and a fifty-fold, ten-fold and ten-fold preconcentration factor for to Zn, Cu and Mn were obtained, respectively.
DETERMINATION OF LOW LEVELS OF COPPER IN NATURAL WATERS BY FLAMEATOMICABSORPTIONSPECTROMETRY USING A SIA SYSTEM WITH A POLY(ETHYLENIMINE) COLUMN. This paper describes a sequential injection analysis (SIA) set-up coupled to a flameatomicabsorption spectrometer (FAAS) to accomplish the determination of low concentrations of copper in drinking waters. Copper is first retained under neutral media in an on-line 29x1.6 mm column filled with poly(ethylenimine) immobilised on silica gel. The retained analyte is then eluted by flowing through the column 250 µ L of a nitric acid solution. The selection of 3.85 ml of sample enabled to obtain a detection limit of 0.27 µ g/L and a sampling rate of about 24 samples/h. There was a good agrement between the results of 12 samples furnished by the proposed procedure and by electrothermal atomicabsorptionspectrometry. Repeatability assessment gave a relative standard deviation of 1.3 % after ten replicate analysis of a sample containing about 70 µ g/L in copper.
not only is Hg fractionation more difficult, but determination of its total content does not occur with the same ease as for most other trace metals. The widely accepted technique, cold vapor atomicabsorptionspectrometry (CVAAS), is much more laborious and time consuming than usual determination by flameatomicabsorption, and not all laboratories have the accessories and the qualifications required for such analysis. There is already equipment designed for direct Hg analysis by atomicabsorption (DMA-80, Direct Mercury Analyzer) in the market and it does a quick scan, but it has a high upfront and operational cost and it is only applicable to samples with low Hg levels and only for total Hg quantification.
The measurements were carried out using an Analytik Jena ContrAA 300 high-resolution continu- um source flameatomicabsorption spectrometer equipped with a xenon short-arc lamp XBO 301 (GLE, Berlin, Germany)  with a nominal power of 300 W operating in a hot-spot mode as a continuum radiation source. Main (324.754 nm), secondary (327.396 nm) and alternate (222.570 nm, 249.215 nm and 224.426 nm) atomic lines for Cu were evaluated to establish the figures of merit of all lines. High-purity acetylene (99.7%, Air Liquid, Sertãozinho, Brazil) was used as fuel gas, and an oxidizing air-acetylene flame was used for analyte atomization. A Perkin Elmer AAnalyst 100 line source spectrometer (Shelton, CT, USA) was also used as comparative technique, and the determination of Cu was carried out in an air-acetylene flame using a Perkin-Elmer Lumina™ hollow cathode lamp.
ATOMICABSORPTIONSPECTROMETRY: THE WAY FOR MULTIELEMENT DETERMINATIONS. This paper present an overview of way covered for the spectrometry of atomicabsorption (AAS), tracing a line of the historical events in its development and its establishment as a multielement technique. Additionally, the efforts carried by through several researchers in the search for the instrumental evolution, the advances, advantages, limitations, and trends of this approach are related. Several works focusing its analytical applications are cited employing simultaneous multielement determination by flame (FAAS) and/or graphite furnace (GF AAS), and fast sequential multielement determination using FAAS are reported in the present review.
A LIQUID-LIQUID MICROEXTRACTION SYSTEM FOR Pb AND Cd ENRICHMENT AND DETERMINATION BY FLAMEATOMICABSORPTIONSPECTROMETRY. A method for determination of lead and cadmium in aqueous samples using solvent microextraction and dithizone as complexing agent with FAAS was developed. Solvent microextraction parameters were optimized. The effect of foreign ions on the extraction yields was studied. The extraction was carried out until the aqueous to organic phase ratio achieved a 250 fold preconcentration of metals. For preconcentration times of 4 min the 3 detection limits, relative standard deviations (n=7) and linear calibration ranges were 1.6 g L -1 , 5.8% and 10.0 – 80.0 g L -1 for lead and 11.1 ng L -1 , 5.9% and
COMBINED DISCRETE NEBULIZATION AND MICROEXTRACTION PROCESS FOR MOLYBDENUM DETERMINATION BY FLAMEATOMICABSORPTIONSPECTROMETRY (FAAS). Simple and sensitive procedures for the extraction/ preconcentration of molybdenum based on vortex-assisted solidified floating organic drop microextraction (VA-SFODME) and cloud point combined with flameabsorptionatomicspectrometry (FAAS) and discrete nebulization were developed. The influence of the discrete nebulization on the sensitivity of the molybdenum preconcentration processes was studied. An injection volume of 200 µL resulted in a lower relative standard deviation with both preconcentration procedures. Enrichment factors of 31 and 67 and limits of detection of 25 and 5 µg L −1 were obtained for cloud point and VA-SFODME, respectively. The developed procedures were applied
Initially, it was evaluated the use of an external calibration approach by using three different media of calibration (A, B, and C; the composition of these media are shown in Table 1) in order to establish a suitable external calibration curve for compensating and/or minimizing possible matrix effects on the determination of Fe in vegetable oil sample microemulsions. The occurrence of matrix effects in FAAS measurements, based on the continuous aspiration system for sample introduction, depends strongly on the differences in viscosity between calibration and sample solutions, because the aspiration efficiency is markedly dependent upon the viscosity. Therefore, it is crucial that both sample and calibration solutions have similar aspiration efficiencies, in order to guarantee the same analyte mass transport efficiencies from these solutions to the flame. This evaluation was performed by comparing the slope of each external calibration curves (obtained in three different calibration media: A, B and C) with the slope of each standard addition calibration