55
EN
Before filling samples with unknown cleaning properties into the measuring
cell, always perform some preliminary cleaning experiments on a glass plate
(e.g. microscopic slide). A sample should only be introduced into the density
measuring cell if it can be removed completely by rinsing (not wiping!) with a
suitable solvent.
Aqueous (polar) samples are best rinsed with polar liquids like water, alcohol
or acetone.
Organic samples (oils, fuels, lubricants, etc.) are best rinsed with organic
liquids (e.g. petroleum naphtha, petroleum ether, toluene, n-nonane).
Samples containing organic and aqueous components (like mayonnaise,
which contains oil and water) may have to be rinsed alternately with organic
and aqueous rinsing agents several times.
Samples containing protein (e.g. beer, milk) should never be brought into
contact with alcohol, because this can cause denaturation of the protein and
precipitation on the glass wall. Protein residues can build up when samples
like beer wort or grape juice are measured over a long time. Enzymatic lab
cleaners are usually best suited for removing these contaminants.
Recommended cleaning agents: "Winepress Cleaner PM Membrane
Presses", Cat. No. 409004, from Wigol®; "TM Desana" from Thonhauser.
Refer to the instructions of the manufacturer concerning the concentration of
the cleaning agent.
Strong alkaline lab cleaners (pH above 10.5) should only be applied briefly
and at temperatures below 25 °C because strong alkalis attack the glass
surface upon prolonged exposure and at high temperatures.
