GRAPHITE-FURNACE ATOMIC-ABSORPTION METHOD FOR THE DETERMINATION OF LEAD IN SUGARS AND SYRUPS

A method was developed for the determination of lead in sugars and syrups. Samples are wet-ashed with a nitric acid-hydrogen peroxide procedure and analyzed by graphite furnace atomic absorption spectrometry. The method involves the use of magnesium nitrate as a matrix modifier, air ashing, platform atomization, and quantitation by peak area measurements with direct calibration against aqueous standards. The instrumental detection limit (based on 3.29 sigma) was 10 pg, or 0.5 mu g/L for a 20 mu L injection, corresponding to a method detection limit of 3.3 ng/g sugar. The characteristic mass was approximately 12 pg. This method was validated by analyzing sucrose and high-fructose corn syrup samples spiked with known quantities of lead. The average recovery was 101 +/- 6%.