**3. Results**

#### *3.1. Elemental Composition of Pristine Ingredients*

The elemental composition of PS9, G30 nanoclays, and natural spring water (ALI) is summarized in Table 2. Below, the results will be discussed from the most innocuous to the most dangerous elements, as well as by the amount in which they were detected.

Regarding PS9 and G30, Ba, Cr, and Li (Class 3) and V (class 2A), were detected in remarkable amounts. The presence of Zr and Nd was also reported. Except for Li, the amount of the aforementioned elements was higher in G30 than in PS9, thus highlighting the presence of more impurities in G30. This statement is in agreement with the solid-state characterization of G30 made by García-Villén et al. [32]. The presence of hazardous elements such as Pb, As, and Cd in fibrous clay minerals have been reported as a common feature of natural deposits, though the present values are minimal with respect to previously reported levels [43].

**Table 2.** Elemental composition of pristine ingredients (PS9 and G30 nanoclays and ALI spring water) determined by ICP-MS. The elements are classified depending on regulations [3,30]. "ND" stands for "Not detected".


With respect to the ALI spring water, the main hazardous impurities detected were Li and Ba, followed by Cr (class 3 elements in all cases). Therefore, the major elements detected (Table 2) belong to class 3 or class 2A [30], which indicates that they are elements whose presence in the raw materials should be borne in mind, though with relatively low toxicity. Additionally, the presence of Cr, Zr, and Nd is not allowed in cosmetics, according to the EC 1223/2009 [3]. From class 2B, only the presence of Se and Tl is banned in cosmetics, though the three of them were detected as traces (Table 2). Ni, which belongs to class 2A and its not allowed in cosmetics, was detected in significant amounts in G30, unlike PS9 and ALI.

Class 1 element group is formed by hazardous elements As, Cd, Hg, nd Pb (Figure 1), all of them prohibited according to EC 1223/2009 [3,30]. As, Cd, and Pb were similar to the ones reported for natural products used in cosmetics [8]. Unlike class 1 and EC 1223/2009, the NNHPD [39] specifies the acceptable limits for heavy metals in topical products (Figure 1), including Sb (class 3). All the aforementioned elements were below the limits established by the NNHPD.

The rest of the elements (from P onwards, Table 2) are not classified in Q3D(R1), thus not belonging to any specific group previously mentioned. Among them, Zr highlights due to the high amount present both in PS9 and G30 in comparison with the rest of the non-allowed elements.
