Optimized laser-induced breakdown spectroscopy for the determination of high toxic lead in edible colors.

An optimized laser-induced breakdown spectroscopy (LIBS) system was utilized as a robust tool for the detection of high toxic lead (Pb) in often used edible colors available in local markets. Edible colors are extensively used in different food stuffs and sweet dish items. To attain a highly sensitive LIBS system for the determination of trace amounts of toxic Pb in edible colors and to achieve the best detection limit, various parametric dependence studies were performed. The quantitative determinations were accomplished under the condition of local thermodynamic equilibrium in terms of optically thin plasma. Besides toxic Pb, other elements like Ca, Mg, Fe, and Na were also detected in edible colors. To estimate the concentration of toxic lead in edible colors, calibration curves were plotted by preparing standard samples of different lead concentrations in an edible colors matrix. Results of the LIBS technique were compared with the outcomes of the same samples studied using a standard analytical technique of inductively coupled plasma-optical emission spectroscopy to confirm the contemporary LIBS setup. The color samples were found above the safe permissible level due to the mass of toxic lead. Limit of detection of the LIBS setup was found at 0.86+/-0.03  ppm for toxic lead present in edible color samples.