Bottle top dispensers

Bottle top dispensers are invaluable for the repetitive measurement of a certain volume of reagent into sample containers for extraction. For example, they find extensive use in soil analysis for dispensing the extracting reagents for phosphate, potassium and magnesium. If the volume setting is adjustable, it is essential to check the amount delivered by weighing the water. Careful priming should ensure that there are no trapped air bubbles. Some manufacturers are:

Bibby Sterilin Ltd: http://www.bibby-sterilin.co.uk/ Brand GmbH & Co. KG: http://www.brand.de/ Eppendorf AG: http://www.eppendorf.com/

Jencons (Scientific Ltd)/Zippette: http://www.jencons.co.uk/ John Poulten Ltd/Ultra Volac:

http://www.pdd.co.uk/experience/medical/volac.htm and http://www.labpages.com/std_home/page0107.html

Table 3.1. Various types of graduated pipette.

Type 1

Calibrated for delivery (EX) from zero at the top to any gradua

tion line down to the shoulder

Type 2

Calibrated for delivery (EX) from any graduation line down to

zero at the jet

Type 3

Calibrated for delivery (EX) from zero at the top to any gradua-

tion line down to the jet

Type 4

Calibrated to deliver from zero at the top down to the jet with

the last drop expelled by blowing

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