*2.3. Determination of Heavy Metals (Pb, Cd, Hg, Cu, and Zn)*

The levels of Cd and Pb in the digest solution of honey were determined according to K ˛edzierska-Matysek et al. [21] by inductively coupled plasma mass spectrometry (Varian MS-820ICP Mass Spectrometer). The gas used to create the plasma was argon (Messer) with 99.999% purity. No reaction chamber (CRI) was used in the analysis. The following settings were used: plasma flow at 16 dm3/min, nebulizer flow at 0.98 dm3/min, RF power of 1.38 kW, and sampling depth of 6.5 mm. The following isotopes of the elements were used: 114Cd, 206Pb, 207Pb, and 208Pb.

Levels of Cu and Zn were analysed with a Varian SpectrAA 240 FS atomic absorption flame spectrometer (Fast Sequential Atomic Absorption Spectrometer, Varian Australia Pty Ltd., Mulgrave, Australia). The following settings were used for Cu: absorption— 324.8 nm, slit width—0.5 nm, lamp current—4 mA. The corresponding settings for Zn were 213.9 nm, 1.0 nm, and 5 mA. The atomizer was a slit burner 100 mm in length operating on a stoichiometric acetylene/air gas mixture. During the analysis of Pb, Cd, Cu, and Zn, quality control was carried out by measuring blank samples and the certified reference material NCS ZC 73014 Tea. The results were expressed as mg/kg fresh weight.

Mercury content was determined using an AMA 254 atomic absorption spectrometer. The analysis was performed without mineralization, which limited the risk of contamination of the sample. Before each measurement, the apparatus was cleaned with air and deionized water.
