Dear Mariam Fares Alsharifi,

In my understanding, you will need a standard solution in an organic solvent if you want to obtain quantitative information. There are multi-element standards for this purpose on the market (e.g., Conostan or other providers).

However, I have one comment regarding experiments you could do until the standard is delivered: if you look only for qualitative information (e.g.., to compare two types of TiO2 catalyst, or to compare two different leaching experiments), you could try a standardless approach. After adding an internal standard (some suitable organic salt which dissolves in hexane and which contains an element certainly not present in your samples, similar in chemical behavior and OES properties than Ti), and establishing the method blank for Ti, you could measure relative intensities. Then, you could at least say, e.g., leached fraction 1 contains about twice as much Ti as leached fraction 2... This is of course only qualitative, as you would actually have to determine the linear range of your measurements using a standard solution, in order to know if it is "allowed" to assume such a linear relation between signal and concentration.