according to the European Pharmacopoeia Specification <2.9.20>
offers a simple method to detect visible particles in transparent liquids.
Matt black panel of appropriate size held in a vertical position
Non-glare white panel of appropriate size held in a vertical position next to the black panel
An adjustable lamp-holder fitted with a suitable, shaded, white-light source and with a suitable light diffuser (a viewing illuminator containing two 13 W fluorescent tubes, each 525 mm in length, is suitable).
The intensity of illumination at the viewing point is maintained between 2000 lux and 3750 lux. Higher values are preferable for coloured glass and plastic containers.
Remove any adherent labels from the container and wash and dry the outside.
Gently swirl or invert the container, ensuring that air bubbles are not introduced
Observe for about 5 seconds in front of the white panel.