Application of laser-induced breakdown spectrometry for direct determination of trace elements in starch-based flours

Spatially resolved laser-induced breakdown spectrometry (LIBS) was investig ated to evaluate the feasibility as a quick and simple method to analyze tr ace elemental concentrations in starch-based flour samples. A Nd:YAG laser beam (lambda =1064 nm. 30 mJ pulse (1)) has been used for generation of las er-induced plasma on sample surface under reduced pressure of argon atmosph ere. A series of starch powder samples containing different concentrations of Sr, Mg, Al, Cu, Cr, K, Mn, Rb, Cd, and Pb were used to construct the cal ibration curves and estimate detection limits of measurements. The calibrat ion graphs for all elements show good linearity (correlation coefficient, r >0.99) in the range 0-160 mug g(-1) or within three orders of magnitude. De tection limits achieved were below 18 mug g(-1) for all elements studied in this work. The lowest detection limit (0.3 mug g(-1)) was obtained from Sr measurement. Precision (%RSD) for the selected analysis was in the range 2 -10%. The standard addition method was applied to assess the accuracy of LI PS using a NIES standard rice sample. The concentrations of Mg and Mn in NI ES standard rice sample determined by spatially resolved LIPS technique hav e good agreements with those of certified value within an error range. The results indicate that spatially resolved LIES has been shown to be an accur ate technique for determining trace elements of ppm (mug g(-1)) level in st arch-based food samples directly with an acceptable precision without any t edious digestion and dilution procedure.