Spectra aa 240z

Reference materials, reagent blanks, and propolis mineralized samples were analysed by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) with Zeeman background correction (Spectra AA 240Z and GTA-120 Varian, Mulgrave, Australia) to determine Cd, Pb, Se, and As and Flame Atomic Absorption Spectrometry (FAAS) (Varian Model 55B, Palo Alto, USA) to determine Cu and K. The detection of metals in both equipment occurred according to the analytical parameters and temperature program indicated in the equipment manual for each metal analysed. The program temperature for each metal analysed by GFAAS is detailed in Table S1. Each sample was analysed in duplicate, and the spectrometer performed two readings of each sample, calibrator, and reference material. The average metal levels were measured in the reagent blank and subtracted from the metal content measured in the samples and reference material [25 (link)]. The resulting concentrations of each metal in the 19 propolis samples were expressed in micrograms (As, Cd, Pb, and Se) or milligrams (Cu and K) of metal per gram (dry weight), and then, the average metal concentration per sample was calculated.

A lyophilizer (Model L101, Liotop, Sao Carlos, SP, Brazil) was used for drying the samples. After drying, the samples were pulverized with a mortar and pestle. Acid digestion of samples was performed in a microwave oven (Start E, Milestone, Sorisole, Italy) [20 (link)]. Determinations of the total concentration of Al in the digested samples were carried out using a Varian Spectra AA 240Z atomic absorption spectrometer (Mulgrave, Victoria, Australia) equipped with a transverse Zeeman effect background corrector and a longitudinal-heated graphite furnace atomizer. An Al hollow cathode lamp was employed as a radiation source, operating at 10 mA. Absorbance signals were measured using the 256.8 nm line at a spectral resolution of 0.5 nm. All measurements were based on integrated absorbance. Argon (99.999% purity, Linde, Pará, Brazil), was used as the purge gas. The temperature programs used for determination Al in samples are shown in Table 1.