ANALYTICAL & LABORATORY EQUIPMENT
reaction. T is is particularly a problem when the base solution is a titration medium, since titrating a solution with an unknown content leads to erroneous results. In addition, carbonates that are by comparison poorly soluble can break down in the solution – for example in an ethanolic potassium hydroxide solution. In turn, the precipitates then form salt crystals which can wear out the piston of the instruments faster and lead to leaky ball valves. To bind the CO2
from the
air, granulated absorbers such as soda lime can be used. Soda lime consists primarily of calcium hydroxide and sodium hydroxide, with an indicator also mixed in. A third function of the drying tube is binding odours. T e Dispensette is a laboratory instrument and should therefore also be operated in a laboratory environment that includes technical ventilation with suffi cient air exchange. In practice, however, local and temporary exposure to strong smelling compounds may occur. A drying tube fi lled with activated carbon can provide relief in these situations.
Filters can
be added for challenging applications
VENTING STOPPER FOR MICROFILTERS If scientists use the Dispensette bottle-top dispenser to dispense sterile media, for example nutrient solutions for cultivating microorganisms, the instrument should fi rst be autoclaved. Instructions on preparing instruments can be found in the
operating manual. T e venting stopper for microfi lters with Luer cone is used to attach a microfi lter over the Luer cone.
Matthias Stein is with Brand.
www.brand.de
The Art of Precision Measurement
Your partner for reliable water activity measurement
Water activity is one of the major parameters when it comes to product quality. It is not only important when it comes to the shelf life of products but also has a great influence on texture, taste and many other properties.
Learn more about water activity in diffrent applications:
www.novasina.ch/lab/applications
www.scientistlive.com 19
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