Buffering capacity - Alkalinity

Alkalinity is measured by titration to pH 5.6, pH 5.4 or 4.5 with HCl. The CO₂ formed is continously removed by nitrogen gas flow-through. The endpoint is indicated with a pH electrode.

Known issues with the parameter and/or important method changes

At present, the acidity of the water is given as negative alkalinity in our databases. 

Current method of measurement

The Aquatic Sciences and Assessment Method

Valid since January 2008
Method: SS-EN ISO 9963-2:1994 (modified). Titration to pH 5.6.
Instruments: Metrohm 855 Robotic Titrosampler with combination electrode. Samples are weighed.

The Soil and Environment Method

Valid since 2014
Method: SS-EN ISO 9963-2:1994 . Titration to pH 5.4 and some samples also to 4.5.
Instruments: Metrohm 855 Robotic Titrosampler with combination electrode. Samples are weighed.

Previous methods

Titration to pH 5.6.

1998-01 – 2007-12
Method: SS-EN ISO 9963-2:1994 (modified). Mettler-Toledo instrument manual.
Instruments: Mettler DL 67 Titrator. Mettler ST 20A Sample changer. Mettler Scale PE 300. Hewlett-Packard Deskjet 520 printer.

1994-07 – 1997-12
Method: Swedish Standard SS 02 81 39 (modified). Mettler-Toledo instrument manual.
Instruments: Mettler DL 67 Titrator. Mettler ST 20A Sample changer.

1985-10 – 1994-06
Method: Swedish Standard SS 02 81 39 (modified). Mettler instrument manual.
Instruments: Mettler Compact Titrator DL 20. Mettler Rototitrator RT 40.

1965-01 – 1985-09
Method: Karlgren, L. 1961, Vattenkemiska Analysmetoder (Hydrochemical Analytical Methods, in Swedish). Modified for automatic titration.
Instruments: Radiometer Autoburette ABU1. Radiometer pH-meter PHM 28. Radiometer Titrator TTT 11. Radiometer electrode pair G 202C/K 401.