Direct solid sampling determination of lead in cheese varieties by high resolution continuum source graphite furnace atomic absorption spectrometry

Lead concentrations in cheese varieties were determined against aqueous standards using high-resolution continuum source graphite furnace atomic absorption spectrometry with direct solid sampling. Cheese samples were dried at 110 °C, chipped finely, and mixed thoroughly; portions of only a few milligrams were weighed automatically on a balance and introduced into the furnace by means of a solid autosampler. Since the samples were not digested, the method was fast, economic and environmentally friendly. The risks of analyte loss or contamination were minimized. The pyrolysis/atomization temperatures were 800/2000 °C. The limit of detection and characteristic mass of the method were 12.0 pg and 6.6 pg of lead, respectively. The lead concentrations in standard reference milk powder were found to be within the uncertainty limits of the certified value. The concentrations of lead in cheese varieties consumed in Turkey ranged from 0.051 to 0.42 mg kg^-1. In addition, the same samples were analyzed after digestion using H₂O₂ : HNO₃ (1 : 3). Finally, micro-scale distributions of lead in cheese samples separated for analysis were determined.