A fast alkaline treatment for cadmium determination in meat samples

Determination of cobalt in biological samples by line-source and high-resolution continuum source graphite furnace atomic absorption spectrometry using solid sampling or alkaline treatment

Surfactant/oil/water system for the determination of selenium in eggs by graphite furnace atomic absorption spectrometry

The amount of sample that is available for analysis in laboratory plant cultivation experiments is usually very limited. Highly sensitive analytical techniques are therefore required, even for elements that are present in the plants at mg g(-1) concentrations, and graphite furnace atomic absorption spectrometry (GFAAS) was chosen in this work because of its micro-sampling capability, and its relatively simple operation. Four micro-methods were investigated for the determination of iron in roots and leaves of rice plants: i) a micro-digestion with nitric and hydrochloric acids, ii) a slurry procedure using tetramethylammonium hydroxide (TMAH) tissue solubilizer, iii) a slurry prepared in 1.4 mol L(-1) nitric acid, and treated in an ultrasonic bath, and iv) the direct analysis of solid samples. The micro-digestion was suffering from high blank values and contamination problems, so that it could not be recommended for routine purposes. The TMAH method exhibited poor precision and occasional low recoveries, particularly for real samples. Direct solid sampling analysis gave results similar to those obtained with the slurry technique with ultrasonic agitation for the determination of iron in certified reference materials with iron content up to about 100 microg g(-1), but was too sensitive for the investigated rice plants, which had an iron content up to several mg g(-1). The slurry technique with ultrasonic treatment of the samples, suspended in dilute nitric acid, was finally adopted as the method of choice. The method was then applied for the determination of iron in the leaves and in different compartments of the roots of two rice cultivars, one sensitive to iron toxicity, an important nutritional disorder, and the other one resistant to iron toxicity. The results suggest that the higher resistance to iron toxicity of the second cultivar is due to a smaller uptake of iron from the soil, resulting in lower iron levels in all compartments of the plant.

This work presents a direct and straightforward approach for the determination of trace elements in fish muscle, oyster, and bovine liver via direct solid sample analysis (SS) using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The preliminary studies revealed the presence of spectral interferences at the analytical line of Ni at 231.096 nm, which could be corrected subtracting the spectrum of SiO and PO from the sample spectra using least-squares background correction. Moreover, all meat samples were proven homogeneous according to the homogeneity factor (H e) (all values were <10 mg½). Pyrolysis (Tp) and atomization (Ta) temperatures were studied and optimized as 800 °C (Tp) and 2500 °C (Ta) for Mn, 700 °C (Tp) and 2600 °C (Ta) for Ni, and 600 °C (Tp) and 2500 °C (Ta) for Rb. Calibration against aqueous standards was proven feasible for Mn determination, whereas Ni and Rb required calibration against solid standards for their quantification. The detection limits achieved were demonstrated adequate for application to food analysis (0.005 μg g−1 for Mn, 0.002 μg g−1 for Ni, and 0.1 μg g−1 for Rb). The developed method was successfully applied for the elemental analysis of fish muscle, oyster, and bovine liver and three certified reference materials, demonstrating good agreement with the certified values and with the reference technique at a 95 % statistical confidence level.

Method development for the determination of nickel in petroleum using line-source and high-resolution continuum-source graphite furnace atomic absorption spectrometry

The aim of this study was to present three sample preparation methods for the determination of Cd, Pb and Sn in meat by Graphite Furnace Atomic Absorption Spectrometry (GFAAS): acid digestion, solubilization with tetramethylammonium hydroxide and formic acid. For the digestion with HNO3, a conventional open system with a cold finger was used. This system helped to avoid losses of analytes and reagents by volatilization, permitting to operate at high temperatures applied at a digester block and reducing the digestion time (∼1 h). Solubilizations were performed at room temperature. The slurry was left standing overnight and remained closed until achieving complete solubilization. The temperature program of the graphite furnace was optimized for each element in the different means of preparation samples using a mixture of Pd–Mg. The figures of merit were similar for all sample preparation methods evaluated. The limits of detection obtained for the acid digestion procedure were 0.0006, 0.0164 and 0.0520 μg g−1 for Cd, Pb and Sn, respectively. In order to evaluate the accuracy of the results obtained by the three sample preparation methods, recovery tests for four real meat samples were performed and the recoveries ranged from 93.7 to 109%, supporting the accuracy of the method. Also, different certified reference materials of meat were analyzed and the results obtained were in agreement with the certified value at 95% of confidence (t-test). The best results were obtained by the acid digestion procedure with the cold finger system. This procedure is faster, the system is semi-closed with no significant contamination or loss of analytes by volatilization and it provides a better signal/noise ratio.

In this work a method for cadmium and lead determination in fresh meat based on slurry sampling graphite furnace atomic absorption spectrometry is proposed. The fresh meat samples were weighed directly into the autosampler cups of the spectrometer using a microbalance and the slurry was prepared using tetramethylammonium hydroxide (TMAH). The use of the response surface method for optimizing the slurry preparation has shown that it was possible to find the optimum zone in the experimental field of the variables under study. Calibration was performed against aqueous standards and a mixture of 0.05% v/v Pd + 0.03% v/v Mg + 0.05% v/v Triton X-100 was used as a modifier. The results obtained for cadmium and lead in two certified reference materials were statistically not different from the certified values on a 95% confidence level, indicating that calibration against aqueous standards is suitable for this application. A comparison of the results obtained by slurry sampling with the digestion method adopted by the Brazilian Ministry of Agriculture showed no significant differences between the results at the 95% confidence level. The positive results obtained in this work suggest that the application of this procedure in other element determinations is worthy of exploration.

Determination of dysprosium and europium in sheep faeces by graphite furnace and tungsten coil electrothermal atomic absorption spectrometry

Optimization of high-resolution continuum source graphite furnace atomic absorption spectrometry for direct analysis of selected trace elements in whole blood samples

Validation of Methods Employing Fast Alkaline Solubilization to Determine Cadmium in Fish Liver, Spleen, Gills and Muscle by Graphite Furnace Atomic Absorption Spectrometry

Sugaring-out assisted extraction (SoAE): A novel approach for the determination of Cd and Pb in milk by graphite furnace atomic absorption Spectrometry.

Direct solid sampling is an attractive alternative for the determination of lead in biological samples, since it requires almost no sample preparation and provides higher sensitivity as no dilution is employed. In addition, the time required for the analysis and the risk of analyte loss or contamination during sample pre-treatment are reduced, the latter being the main problem associated with the usual digestion and dissolution procedures. In the present work, treating the determination of Pb in biological samples at 217.001 nm with solid sampling graphite furnace atomic absorption spectrometry (GF AAS), it will be shown that high-resolution continuum source AAS (HR-CS AAS) provides a variety of new possibilities for method development that have been unavailable previously. The use of ruthenium as a permanent modifier allowed a pyrolysis temperature of 900 °C to be applied, which was sufficient to eliminate the continuous background that preceded the analyte signal due to incomplete elimination of the matrix when lower pyrolysis temperatures were used. At atomization temperatures higher than 1500 °C, background absorption with pronounced fine structure followed the atomic signal. This was due to the electron excitation spectrum of PO, as was demonstrated by applying a least-squares background correction algorithm using the spectrum obtained by vaporization of (NH4)2HPO4 as a reference. Under optimum conditions, interference-free determination could be carried out by setting integration limits adjusted to integrate only the atomic signal; calibration against aqueous standards was performed and compared with calibration against a solid certified reference material (CRM). A total of seven biological CRM were analyzed (bovine muscle, pig kidney, lobster hepatopancreas, human hair, dogfish liver, oyster tissue and bovine blood), and the determined concentration of Pb was in agreement with the certified values using both calibration procedures, according to the t-test for a 95% confidence level. The detection limit (3s, n = 10) was 0.01 μg g−1, and the precision was typically better than 10%. The method is therefore adequate because of its simplicity, high sensitivity, good accuracy and wide applicability.

Feasibility of eliminating interferences in graphite furnace atomic absorption spectrometry using analyte transfer to the permanently modified graphite tube surface

A slurry sampling method was developed for the fast determination of Pb, Ni, Fe, and Mn in construction materials by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS). For sample introduction into the GF, stable slurries were prepared by sonicating 10 mg of ground solid sample in 10.0 mL of 1% (v/v) Triton X-100 and 1% (v/v) HNO3 solution for 1.0 min. The determination of the four elements was carried out in three measurement runs, with Ni and Fe being determined simultaneously. The HR-CS GFAAS measurements were performed using analytical lines with adequate sensitivity, considering the content of each element in the material: Pb at 283.306 nm (42%), Mn at 403.080 nm (6.7%), Ni at 232.003 nm (100%) and Fe at 232.036 nm (1.4%). The pyrolysis and atomization temperatures and the use of chemical modifiers were optimized using both aqueous standards and slurry samples. At optimal conditions, samples with concentrations of Pb from 1.5 to 80 μg g-1, Ni from 4.0 to 75 μg g-1, Mn from 2.0 to 600 μg g-1, and Fe from 0.15 to 60 mg g-1 could be determined using a unique sample suspension. To assess the validity of the method, a fly ash certified reference material (CRM) was analysed using the slurry sampling HR-CS GFAAS method; this CRM and the construction material samples were also analysed by HR-CS GFAAS after the digestion of the samples. The obtained results using both methods were statistically comparable (Student's paired t-test for two independent methods at a 95% confidence level) demonstrating the suitability of the proposed method.

Novel extraction induced by microemulsion breaking for Cu, Ni, Pb and V determination in ethanol-containing gasoline by graphite furnace atomic absorption spectrometry