2,3-Diaminonaphthalene is a highly selective fluorometric and colorimetric reagent for selenium detection, and it is also used for the fluorometric determination of nitrite.

Instructions
I. Detection of selenium ions:
1. Solution preparation:
1) First dissolve 2,3-Diaminonaphthalene (usually provided in solid form) in an appropriate solvent, usually pure water or an appropriate amount of acidic solution. The concentration is generally 0.1-10 mM, and the specific concentration can be adjusted according to experimental requirements.
2) It is necessary to prepare a solution containing an appropriate amount of selenium ions, and the concentration is selected according to the experimental design and the required detection sensitivity.
2. Reaction steps:
1) Add 2,3-Diaminonaphthalene solution to the sample, and often react in an acidic environment (such as pH 4-5) to promote the formation of products.
2) The reaction temperature is generally maintained at room temperature, and the reaction time is usually 10-30 minutes. The specific time can be optimized as needed.
3. Detection:
1) Colorimetry: Use a spectrophotometer to detect the absorbance of the reaction product. Usually, the reaction product has an absorption peak at a specific wavelength (such as 320-350 nm). 2) Fluorescence method: If fluorescence determination is performed, it is necessary to excite at a specific wavelength (such as 320 nm) and detect fluorescence emission (usually 400-460 nm). The fluorescence intensity of the product is proportional to the concentration of selenium ions.
3) Data analysis: By comparing with the standard curve, the selenium ion concentration in the sample can be quantitatively analyzed.