Potassium Chloride Filter, Sodium Iodide Filter and Sodium Nitrite Filter
| Description | Liquid filters with sharp cut offs in transmission at specified wavelengths, certified |
| Use | Detection of stray light in the UV range (at wavelengths of 198 nm to 385 nm, depending on the chosen filter) |
| Material | Aqueous solutions sealed in Hellma precision cells, made from quartz SUPRASIL® |
667-UV1 Kaliumchlorid-Filter
667-UV10 Natriumiodid-Filter
667-UV11 Natriumnitrit-Filter
These calibration standards show a remarkably high absorbance below a particular wavelength (cut-off wavelength) in the UV range. Using this phenomenon, the spectrophotometer can be checked for stray radiation. The measurement of stray light is carried out against a reference filter containing ultra purified water, which is supplied with every set of stray light filters. The procedure is the same for any kind of cut-off filter.
Reference filter: 667-UV12 Ultra purified water
Handling:
The spectrophotometer is set to a wavelength which is about 30 nm higher than the cut-off wavelength of the stray light filter being used. Using for example potassium chloride, it is suggested to start at 230 nm. Then scan down into the short wave region and observe the absorbance values below the cut-off wavelength. The stray light value for the measuring device results from the difference between the maximum measurable absorbance and the displayed absorbance.
