Titration with a Bottletop Burette
Simplify Titration with a Bottletop Burette
Titration is a common laboratory exercise employed to determine the unknown concentration of a substance called the analyte (a.k.a. titrand or what you are analyzing for) in a solution. This is accomplished by carefully and precisely metering a reagent (a.k.a. titrant) into the solution until a reaction occurs. The reaction may be as simple as a change in color or more complex such as a change in pH or electrical conductivity.
The metering is accomplished by using burettes containing the reagent. Glass tube burettes with etched volume indicators such as milliliters are used to conduct titration exercises. Glass tube burets are usually clamped to a support stand and suspended over the beaker or flask containing the solution being analyzed. The reagent is metered into the beaker or flask by turning a dispensing valve at the buret base and observing how much is dispensed before a reaction occurs.
Closely related to the burette is the pipette, which is an open tube and employed to dispense its entire content rather than a metered amount via a burette’s stopcock. Filling a pipette is more exacting than a burette because the meniscus of the titrant must be taken into account. Spills are not uncommon when adding reagents to burettes and pipettes. The operation calls for an accurate eye and steady hand.
If this sounds complicated it’s because it is complicated. Not only is precision paramount, cleaning and maintaining glass tube burettes and pipettes is absolutely necessary as well as being time consuming. Cleaning and drying usually must be undertaken after each series of measurements. Incidents of breakage are not unknown.
Simplified Titration Using Bottle-Top Burettes
Glass tube burettes and pipettes are often the instruments of choice in labs conducting frequent titration studies involving a variety of reagents and analytes. In instances where ongoing titration of a single reagent is common, a bottletop burette such as the CAT Contiburette series provides substantial advantages in throughput and efficiency. A common application is quality control to comply with GLP and ISO criteria.
CAT Contiburette models, either motorized or hand powered, are designed to dispense reagents in micro liter (µl) subdivisions of 1µl, 10µl and 20µl. The assembly is fitted to the top of a reagent bottle and uses highly corrosion-resistant pump materials of construction to meter precise amounts of reagent into the sample flask or beaker. Reagent dispensing quantities and rates are set by the operator using the intuitive LED display panel. Motor-driven models powered by a 9-volt transformer can be connected to a PC for or printer for GLP record keeping and can be controlled by computers to free personnel for other tasks. Hand-powered models use AA batteries but otherwise operate with the same accuracy as motor-driven models.