Optimization and Application of a Slurry Sampling Method for the Determination of Total Fluorine in Flour Using a High-Resolution Continuum Source Graphite Furnace Molecular Absorption Spectrometer

A slurry sampling method was described for the determination of total fluorine in flour via molecular absorption of calcium monofluoride (CaF) at 660.440 nm using a high-resolution continuum source graphite furnace atomic absorption spectrometer (HR-CS GF AAS). The slurries were prepared in 1 % Triton X-100, kept in an ultrasonic bath for 15 min, mixed in a shaker for 5 min (750 rpm), and then vortexed for 30 s shortly before sampling. The samples were mixed with 40 μg of Ca in the graphite furnace, pyrolyzed at 900 °C, and the absorbances for CaF were measured at 2200 °C. The LOD and characteristic mass of the method were 0.22 and 0.16 ng, respectively. The F concentrations of certified reference bush branches and leaves were determined in the uncertainty limits of the certified values. Finally, the F concentrations of different types of flours were determined applying the optimized conditions.