Titration with Alcoholic Potassium Hydroxide Solution

In the production control and qual- are highly accurate with much less An initial difficulty was that the cleaning cycle could be extend- ity monitoring of our corrosion pro- variability. The advantage of the crystals ended up in the filling ed to approximately 12 weeks. tection, hydraulic, cutting and gear easy dismantling of the instrument, valve or dispensing valve, causing By now, the instruments have oils, we determine the acid content for cleaning purposes or replace- these to leak – a problem with been in use for almost one year, by titration (color change). De- ment of piston or cylinder is only all ball valves. After rinsing with di- and it appears as though the pis- pending on the task definition, we noticed upon further inspection. luted hydrochloric acid (approx. ton/cylinder assembly can last for use either a 0.1 M or 0.5 M alco- Most helpful for our applica- 3 %), the instrument was again one year and possibly longer with holic potassium hydroxide (KOH) tions were the practical notes on ready for immediate use. In addi- regular cleaning, even with this solution. handling alcoholic KOH in the in- tion to the points mentioned above, difficult titration medium. Whenev- Alcoholic KOH is considered to struction manual, in addition to the switching to commercially pre- er necessary we can simply replace be a difficult titration medium due direct contact to the manufacturer pared titration solutions also the piston and cylinder ourselves. to the extensive crystallization, and when there were questions on use. helped to prevent this. All in all, compared to the pre- not every burette passes the practi- Thus, for example, it is recommend- It is also recommended to clean vious model as well as to glass bu- cal usage test. Until now, we have ed to adjust the filling tube length the dispensing cylinder regularly. rettes, the new Titrette saves a worked with glass burettes and on to maintain a distance of approx. When the PTFE piston is moved great deal of time, since cleaning a trial basis with the Burette Digi- 20 mm from the bottle’s bottom. downwards, small amounts of the can be done much faster and easier tal III. Since September 2008 we This is important since, as in con- medium inevitably remain on the than before. have been using the new Brand trast to aqueous KOH, the develop- cylinder wall. The solvent evapo- Titrette satisfactorily. It is a manu- ing potassium carbonates formed rates immediately, and carbonate ally driven digital bottletop burette from atmospheric CO2 are nearly crystals form and accumulate at similar to the previous model, but insoluble in alcohol and therefore the upper end of the glass cylinder. it has been substantially improved. some crystals always accumulate In order to avoid premature wear After extensive testing we can on the bottle’s bottom. of the PTFE piston, the crystals Contact: confirm the easy operation and ro- Additionally, we were recom- have to be removed approximately Manuel Smetz bust construction of the Burette, mended to use a soda lime-filled every four weeks. After modifying Fuchs Europe Schmierstoffe GmbH QM (Quality Management) that means instrument properties drying tube in order to minimize our operating procedure as de- Mannheim, Germany which are of particular importance the formation of carbonates and scribed above and refilling the dis- Tel.: +49 621 3701 475 for us working in shifts. Drop wise the consequential annoying degra- pensing cylinder immediately after Fax: +49 621 3701 478 titration proceeds much more sim- dation of the solutions from the each titration, the forming of crys- [email protected] ple, and the measurement results outset. tals was substantially reduced and www.fuchs-europe.de

G.I.T. Laboratory Journal 09–10/2009, p 37, GIT VERLAG GmbH & Co. KG, Darmstadt