Development of a Quantitative Edxrf Method for Determining the Concentration of Palladium Applied to Tobacco

A quantitative energy dispersive X-ray fluorescence (EDXRF) spectrometry method was developed for determining the concentration of palladium (Pd) applied to tobacco cut filler. Control and standards were created in-house with different levels of Pd concentration. After application of the Pd in a salt solution, the tobacco had an average oven volatiles (OV) value of 27.6%. Three aliquots were analyzed at each concentration level by EDXRF and inductively coupled plasma atomic emission spectrometry (ICP-AES). Results were plotted against target values to perform a linear regression. EDXRF and ICP-AES coefficient of determination (R) values were both lower than the accepted minimum value of 0.990. Also, measured concentrations varied significantly between replicates. To improve the calibration technique, two options were evaluated: (a) Improve sample homogeneity by lyophilizing and finely grinding the tobacco, and (b) Improve the linear fit of the EDXRF calibration curve by plotting against ICPAES results. EDXRF and ICP-AES analyses were performed on lyophilized samples with an average OV value of 3.3%. Results demonstrated minimum variation between replicates and distinct variation between levels of concentration. Results were plotted against target values, and both EDXRF and ICP-AES R values improved. For evaluation of option (b), EDXRF results were plotted against ICP-AES results to create the calibration curve with an R value of 0.994. Compton scatter was implemented in the method to account for the difference in the moisture content of the lyophilized standards and the unknown samples with high OV values.