People who have not been in contact with luminol may not have a good understanding of what it does. But if you are interested in criminal investigation, you will know that it is the magic of solving crimes. Because it emits a kind of blue light when it encounters blood, even if you wash it with water or detergent, it cannot block its light, but there may be differences in luminous intensity. So what exactly affects the luminous intensity of luminol?

The effect of pH on the strength of luminol

pH plays a vital role in the luminescence of luminol luminescence system. At lower pH values, the intensity of luminol decreases sharply, while at higher pH values, a significant increase in the intensity of luminol is observed. Their effect on the strength of luminol at different pH. At lower pH values, these compounds showed an inhibitory effect on the intensity of luminol, while at higher pH values, a significant increase in the intensity of luminol was observed.

The maximum luminous intensity measured in the range of pH 8.0 and pH 9.5. In this pH range, both suppression and enhancement signals are observed. When we compare the luminous intensity at pH 8.0 and pH 9.5, the relative luminous intensity at pH 8.0 is lower and decreases with a half-life of 20 minutes. However, the relative luminous intensity at pH 9.5 was higher, lasted longer, and then slowly decreased, so 30% luminous intensity was recorded even after 3 hours. Luminol has a strong and stable chemiluminescence signal at alkaline pH.

Influence of Luminol Concentration on Luminous Intensity

The concentration of luminol is an important factor affecting the luminous intensity. The intensity of luminol's luminescence depends not only on the concentration of luminol, but also on other factors, such as the concentration of oxidants, enzymes, and pH. The effect of luminol concentration was studied by keeping the concentration of H 2 O 2 and silver nanoparticles constant. The concentration of luminol they use is 0.01-1 mmol/L. The maximum luminous intensity recorded at a luminol concentration of 0.3 mmol/L. The luminous intensity increases linearly with the increase of luminol concentration in the range of 0.01 to 0.3 mmol/L. However, a further increase in the concentration of luminol resulted in a decrease in luminous intensity. A number of studies have shown that the luminescence signal increases linearly with the increase of luminol concentration, reaching its maximum intensity at a specific concentration. Above the luminol concentration, the luminescence signal decreases.