Direct solid sampling of biological species for the rapid determination of selenium by high-resolution continuum source graphite furnace atomic absorption spectrometry.

A direct solid sampling method based on high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) for the determination of selenium (Se) in biological tissues was optimized. The main analytical line of Se at 196.0267 nm was used to carry out all HR-CS AAS measurements. Different chemical modifiers were evaluated to prevent the loss of Se during the application of the GFAAS temperature program and avoid the interferences due to the presence of phosphorus compounds in sample matrix. The best results were achieved using ruthenium coated platforms and a palladium nanoparticle suspension (Pd NP) as co-injected modifier. Calibration was performed using aqueous standard solutions of Se(IV). For solid sampling, the optimal range of sample mass was between 0.2 and 0.8 mg. The limit of detection (LOD) was 0.06 ng (0.075 µg g-1 using a sample mass of 0.8 mg). The developed solid sampling HR-CS GFAAS method was used for Se determination in two certified reference materials of dogfish tissues and lyophilized and powdered real samples of fish tissues and chicken liver. The precision obtained in these analyses, expressed as relative standard deviation (RSD), was between 5.5 and 8.6% (n = 6). For validation purposes, the results obtained by the solid sampling HR-CS GFAAS method were compared with those found performing the analysis by HR-CS hydride generation AAS (HR-CS HGAAS) after microwave acid digestion of the samples. The Se concentrations obtained for both methods agreed at a 95% confidence level (Student's t-test), indicating the suitability of the proposed solid sampling HR-CS GFAAS method to determine Se in biological samples.

Micro-sampling method based on high-resolution continuum source graphite furnace atomic absorption spectrometry for calcium determination in blood and mitochondrial suspensions.

A micro-sampling and straightforward method based on high resolution continuum source atomic absorption spectrometry (HR-CS AAS) was developed to determine extracellular and intracellular Ca in samples of interest in clinical and biomedical analysis. Solid sampling platforms were used to introduce the micro-samples into the graphite furnace atomizer. The secondary absorption line for Ca, located at 239.856nm, was selected to carry out the measurements. Experimental parameters such as pyrolysis and atomization temperatures and the amount of sample introduced for the measurements were optimized. Calibration was performed using aqueous standards and the approach to measure at the wings of the absorption lines was employed for the expansion of the linear response range. The limit of detection was of 0.02mgL-1 Ca (0.39ng Ca) and the upper limit of linear range was increased up to 8.0mgL-1 Ca (160ng Ca). The proposed method was used to determine Ca in mitochondrial suspensions and whole blood samples with successful results. Adequate recoveries (within 91-107%) were obtained in the tests performed for validation purposes.

Determination of essential elements in beverages, herbal infusions and dietary supplements using a new straightforward sequential approach based on flame atomic absorption spectrometry.

A simple method based on FAAS was developed for the sequential multi-element determination of Cu, Zn, Mn, Mg and Si in beverages and food supplements with successful results. The main absorption lines for Cu, Zn and Si and secondary lines for Mn and Mg were selected to carry out the measurements. The sample introduction was performed using a flow injection system. Using the choice of the absorption line wings, the upper limit of the linear range increased up to 110mgL-1 for Mg, 200mgL-1 for Si and 13mgL-1 for Zn. The determination of the five elements was carried out, in triplicate, without the need of additional sample dilutions and/or re-measurements, using less than 3.5mL of sample to perform the complete analysis. The LODs were 0.008mgL-1 for Cu, 0.017mgL-1 for Zn, 0.011mgL-1 for Mn, 0.16mgL-1 for Si and 0.11mgL-1 for Mg.