The thermal stability of the bleachable and unbleachable components of the electron spin resonance signals in
quartz grains from modern fluvial sediments were investigated. It was found that the unbleachable Al center is
thermally more stable than the bleachable component, hence the unbleachable component can be extracted by
heating. Protocols for equivalent dose evaluation with preheating are proposed, in which the procedure of
bleaching is replaced by “partial annealing” (heating at 280 ◦C for 15 min) for the Al center and by “annealing”
(heating at 400 ◦C for 1 h) for the Ti-Li and Ti-H centers. The dose recovery test confirmed that the proposed
protocol works practically, and that the regenerative protocol is better than the additive dose protocol in the
aspect of the statistical errors. Appropriate partial annealing conditions to extract the unbleachable Al centers
may need to be investigated for each sample.
