The sodium nitrite liquid filter (UV11) consists of 50 g/l sodium nitrite in pure water. This filter is suited to check the stray light of a spectrometer in the spectral range between 300 nm and 386 nm, its cut off is at about 385 nm.
Two regulations - two measuring methods
Currently there are different methods used in the European Pharmacopoeia (EP) and in the United States Pharmacopeia (USP) to determine the stray light.
Measurement of sodium nitrite (UV11) against reference filter pure water (UV12)
Typical spectrum of the stray light filters in accordance to Ph. Eur.
Measurement of sodium nitrite (UV11, PL 10mm) against reference filter sodium nitrite (UV11H, PL 5mm)
Typical spectrum of stray light filters according to USP <857>
Experiences from daily practice show that the values determined in this stray light measuring method are instrument-dependent. This means the wavelength of the peak varies depending on the spectrophotometer performance. It is important for the user to know that the measured maximum absorption in the checked range is decisive for this checking method and that it should be higher than 0.7 Abs.
|ARTICLE-NO.||EP-Set: 667102 (UV11/UV12) Request this article |
USP-Set: 667102H (UV11/UV11H)
|APPLICATION||Checking stray light in the spectral range of 300 - 386 nm according to EP and USP|
|CONTENT||Sodium nitrite 50 g/l in pure water|
|STANDARD CERTIFICATION||Cut-off wavelength: 385 nm |
Slit width: 2 nm; with DAkkS calibration certificate
|POSSIBLE CERTIFICATION||Cut-off wavelength: fix |
Slit width: 2 to 5 nm