To determine whether the analytical performance could be further improved and/or optimized, we performed the autocatalysis reaction in buffers of different nature adjusted at different pHs (it is to note that DI from the Bacillus Stearothermophilus has a bell-shaped activity in the pH range 6.5 to 10.5, with an optimum at pH 8.0 59 ). Among the different organic and inorganic buffers investigated (see SI and Figures S13 to S20), the glycine buffer at pH 10 was found superior. The analytical performances obtained with this buffer were indeed clearly improved (Figure ), leading to a dynamic concentration range over nearly 3 decades (i.e., from ca. 0.01 to 10 µM H2O2) and a LOD as low as 5 nM H2O2 in less than 10 min reaction time. This is a very appealing performance since in terms of LOD, it is competitive with the best H2O2 detection kits currently commercially available (a LOD of 10 nM H2O2 within 30 min incubation time is reported for the popular fluorescent-based Amplex red® hydrogen peroxide/peroxidase assay ). Another buffer particularly attractive is the CAPS buffer at pH 9.5 (Figure ). In spite of a slightly longer reaction time, the data indicates the possibility to reach the nanomolar H2O2 concentration range in less than 50 min. It is to note that with some buffers the autocatalysis was found to be inefficient in producing well-defined or discernible autocatalytic responses. This was especially true with the borate buffer (Figure ). It was also observed in some buffers an anomalous shift of the nonspecific blank response to shorter times compared to the responses recorded at the lowest H2O2 concentrations. All these behaviors suggest that the buffer plays an active role in the autocatalysis that we have not yet been able to elucidate.