# Investigation of Element Migration from Aluminum Cooking Pots Using ICP-MS
## 3 Results and Discussion
### The Results of XPS Analysis  
An additional chemical analysis technique was employed to further verify the presence of detected elements in food samples. X-ray photoelectron spectroscopy (XPS) is a surface-sensitive technique used for the quantitative analysis of elemental composition, particularly at the top surface layers of samples. XPS analysis was conducted to confirm the concentration of detected elements in the cooked food samples. As mentioned earlier in the previous subsection, the prepared food samples primarily consist of rice, which was dried and ground into a powder form for XPS analysis. It is worth mentioning that XPS analysis was performed on all samples collected from various food experiments, as shown in Table 1; however, only one example related to the ACP-5 condition will be presented to avoid repetition. Figure 6 displays the XPS survey (full) scan spectrum collected from food samples prepared according to the ACP-5 condition outlined in Table 1. The \(x\)-axis of this spectrum covers the binding energies of all possible elements that could be detected in the food samples prepared using aluminum cooking pots, including Al, Fe, As, Cd, and Pb. However, only carbon and oxygen were detected and quantified in the examined food samples, as indicated by the XPS survey scan presented in Figure 6. The corresponding quantitative chemical analysis is inserted in the upper-left corners of the same figure. Figure 7 presents the XPS high-resolution spectra related to the survey scan in Figure 6, specifically for the ACP-5 experiment conditions. The high-resolution scan was performed to identify the elements of interest. However, Figure 7 shows that none of these elements, including C 1s, O 1s, Al 2p, Fe 2p, As 3d, Cd 3d, and Pb 4f, were detected except for carbon and oxygen. The XPS technique did not detect any of the elements of interest in the prepared food samples using aluminum cooking pots because the content of these elements fell below the detection limit of the XPS technique. The reported detection limit for XPS is typically below 1 at.% to 0.1 at.% [45; 46; 47], meaning that trace elements below this concentration cannot be detected by XPS. Based on the ICP-MS results presented in Table 1, the concentration of all detected elements is indeed below the detection limit of the XPS technique.  
In the present study, three analytical methods were applied to quantify the elements migrated to food to ensure the accuracy and reliability of the results. Different methods may display different levels of sensitivity and detectability of different elements which allow results validation and confirmation. Applying these three methods provided a comprehensive analysis and confidence with the results. Table 8 shows the principle, advantages, disadvantages, and detection limits of the three techniques applied in the current study.  
Figure 6: XPS survey scan spectrum collected from food samples prepared by aluminum cooking pot according to ACP-5 experiment conditions.  
Figure 7: XPS high resolution spectra related to the survey scan in Figure 6 (ACP-5 experiment conditions): (**a**) C 1s; (**b**) O 1s; (**c**) Al 2p; (**d**) Fe 2p; (**e**) As 3d; (**f**) Cd 3d; and (**g**) Pb 4f.