Acetone liquid filter for checking stray light (322 nm)

The acetone liquid filter (UV19) consists of pure acetone. This filter is suited to check the stray light of a spectrophotometer in the spectral range between 250 nm and 324 nm, its cut-off is at about 322 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.

Checking stray light according to EP (European Pharmacopoeia)

Measurement of acetone (UV19) against air (high-purity acetone is used and not dissolved in water)

Currently, the use of the acetone stray light filter is required only in the United States Pharmacopeia (USP) for the determination of the stray light in the spectral range from 250 nm to 324 nm.

Typical spectrum of the stray light filters in accordance to Ph. Eur.


Checking according to USP<857> (United States Pharmacopeia)

Measurement of acetone (UV19, PL 10mm) against reference filter acetone (UV19H, PL 5mm)

Typical spectrum of stray light filters according to USP <857>


Note on measuring method according to USP

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 Art-No.: 667019 (UV19)      Request this article
USP-Set: 667119H (UV19/UV19H)    
APPLICATION Checking stray light in the spectral range of 250 - 324 nm according to EP and USP
CONTENT high purity Acetone
STANDARD CERTIFICATION Cut-off wavelength: 322 nm
Slit width: 2 nm; with DAkkS calibration certificate
POSSIBLE CERTIFICATION Cut-off wavelength: fix
Slit width: 2 to 5 nm


Reference Materials (Brochure & User Manual EN)


Liquid-based, optical reference material UV19 and UV19H (Safety Information EN)



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