An ultrasensitive chemiluminescence sensor for sub-nanomolar detection of manganese(II) ions in mineral water using modified gold nanoparticles

A simple, rapid, facile and ultrasensitive chemiluminescence (CL) sensor was developed for detection of Mn 2+ in mineral water samples. The developed CL sensor was based on the enhancement effect of manganese ion (Mn 2+ ) on the CL between luminol-modified AuNPs and AgNO 3 system. In the absence of Mn 2+ , the CL intensity from the luminol-modified AuNPs and AgNO 3 was relative weak owing to the bad stability of superoxide anion radical (O 2 − ) which was the key intermediate for the CL reaction. However, the addition of Mn 2+ to this CL system would generate hydrogen peroxide (H 2 O 2 ) according to the specific reaction of Mn 2+ and O 2 − . The produced H 2 O 2 had a better stability and reaction activity, thereby enhancing the CL emission. This phenomenon allowed to selective and highly sensitive detection of Mn 2+ . Under the optimal sensing conditions, the developed CL sensor showed a wide linear range for Mn 2+ detection in the range of 1–600   nM, with a detection limit of 0.3   nM at a signal-to-noise of 3. This sensitivity was about 2–3 orders of magnitude higher than that reported techniques based on metal nanoparticles-based optical sensors . In addition, the developed CL sensor exhibited excellent selectivity toward Mn 2+ over other metal ions , and it had a good stability and reproducibility.