Direct Sampling Electrothermal Atomic Absorption Research Articles

Determination of cadmium and lead in fresh fish samples by direct sampling electrothermal atomic absorption spectrometry

The determination of cadmium and lead in fish samples has large analytical interest due to the potential toxicity of these elements. The development of fast and reliable analytical methods is extremely important for an effective control of contamination. In this work, the feasibility of Cd and Pb determination in fresh fish samples using direct sampling by electrothermal atomic absorption spectrometry (DS-ET AAS) was investigated. For optimization of the furnace temperature program, pyrolysis and atomization curves with TORT-2 and DORM-3 certified reference materials were carried out using chemical modifier (0.05% Pd + 0.03% Mg + 0.05% Triton X-100). The figures of merit obtained were: characteristic mass of 1.0 pg and 16 pg and limit of detection (LOD) of 0.2 μg kg−1 and 1.0 μg kg−1 for Cd and Pb, respectively, based on 8 mg of sample mass. The results obtained for certificated references materials were statistically not different from the certified values at 95% confidence level, using the calibration with aqueous standards, showing that this calibration method is suitable for this application. For assessment of the accuracy of the method, fresh fish samples were digested. The results obtained with direct determination of Cd and Pb in fresh fish samples and with microwave assisted acid digestion were statistically accordant. The developed method for analysis of fresh fish samples is accurate, simple, fast and suitable for routine application, avoiding digestion procedures or the drying/lyophilization and grinding procedures, usually used in DS analysis, reducing the preparation time, risk of contamination and costs.

Determination of copper, iron and vanadium in petroleum by direct sampling electrothermal atomic absorption spectrometry

A procedure for the direct determination of Cu, Fe and V in petroleum samples by electrothermal atomic absorption spectrometry using a solid sampling accessory, without any sample pre-treatment or dilution, is proposed. A Pd + Triton X-100 solution was used as chemical modifier. The pyrolysis and atomization temperatures, as well as the Pd mass were defined by multivariate optimization. The other parameters of the temperature programs were defined by univariate optimization. The limits of detection at the optimized conditions were 10, 200 and 800 pg for Cu, Fe and V, respectively, for typical sample masses ranging from 0.10 to 3.00 mg. Method accuracy was confirmed by the analysis of oil certified reference materials as well as by comparison with independent methods. Aqueous calibration solutions were used and no statistically significant difference (analysis of variance) was observed between obtained and expected values.

A low cost and sensitive procedure for lead screening in human whole blood with sequential injection-hydride generation-atomic fluorescence spectrometry

An automated sequential injection hydride generation (HG) atomic fluorescence spectrometric (AFS) method was developed, with the aim of screening blood lead levels for Chinese citizens, especially for children. Lead hydride was generated from acid solution, with potassium ferricyanide as an oxidizing agent, by reaction with alkaline tetrahydroborate solution. The hydride was separated from the reaction medium in a gas–liquid separator (GLS1) and swept directly into the atomizer. A thorough scrutiny was made of the various factors, including the modification of the AFS instrument and related parameters, the various wet digestion protocols, the variables of the flow system and the reaction conditions. Under the optimized conditions the blank signal was satisfactorily minimized, giving rise to a limit of detection of 0.014 μg l−1, defined as 3 times the blank standard deviation divided by the slope of calibration graph, and a RSD value of 0.7% (at the 2.0 μg l−1 level, n = 11), along with a sampling frequency of 120 h−1. The sensitivity of the procedure was found to be significantly superior to those obtained by HG-atomic emission spectrometry (AES), direct sampling electrothermal atomic absorption spectrometry (ETAAS), tungsten filament atomizer ETAAS,and quartz tube atomizer HG-AAS; it was even lower than those by in-atomizer-trapping HG-ETAAS and comparable to ICPMS-based methods. The accuracy and practical applicability of the procedure were validated by analysing certified reference materials of frozen cattle blood GBW 09139 and GBW 09140, and further demonstrated by spiking recoveries of lead in human whole blood samples.