Characterization of solid magnetic nanoparticles by means of solid sampling high resolution continuum source electrothermal atomic absorption spectrometry
Magnetic nanoparticles (MNPs) are a new kind of nanometer-sized superparamagnetic material with potential applications as magnetic carriers for various biomedical uses, wastewater remediation, preconcentration of various anions and cations, etc. The excellent properties of MNPs are strongly influenced by the size of the nanoparticles. Another important factor is the amount of iron present. In this work, a simple and inexpensive approach was developed for the direct determination of the Fe concentration and particle size of solid MNPs by solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry (HR CS GFAAS). A new strategy of evaluating the area and upslope of the obtained absorbance signals for a line of Fe (352.614 nm) with low sensitivity was developed for both determinations. For this purpose, five furnace program parameters, atomization heating rate, atomization temperature, pyrolysis heating rate, pyrolysis temperature and pyrolysis hold time, were optimized with the employment of two multiple response surface designs. With the optimized furnace parameters, satisfactory calibration curves were obtained with liquid iron standards (for Fe determination) (R ≥ 0.995) and with MNP samples with a certified size of particle (for size particle determination) (R ≥ 0.990). The determinations of the MNPs’ size and their iron percentage were validated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. This method can be employed in the optimization of the synthesis of MNPs by the coprecipitation method.