 Carbon dots, CDS, have shown promise as a low-cost alternative to traditional pH-sensing materials due to their low cost, ease of manufacture, low toxicity and negligible photobleaching. In this study, four new CDS were synthesized using different precursor combinations and compared against the previously reported CD. All five CDS showed a decrease in fluorescence intensity with increasing pH, but only three of them exhibited a decrease in fluorescence lifetime. This suggests that the precursor's use may play a role in determining the fluorescence behavior of the CDS. This article was authored by Victoria K. Sopotka, Adam Eltruskowicz, Thor Scottving, and others.