EU A.3: Relative density (liquids and solids)

The density of a substance is environmentally relevant because it is helpful in estimating the distribution of the substance within and between water, soil and air.

The purpose of the study is to determine the relative density at a specific temperature with a pycnometer in case of liquid test item or by means of a gas comparison pycnometer for the solid test item.

Study Design

Course of the test


Apparatus - Glass-pycnometer

Test Condition - 20 °C ± 1.0 °C

The density will be calculated from the difference in weight between the full and empty pycnometer and its known volume. A calibrated pycnometer (with stopper) will be used. It will be immersed up to its neck in a constant temperature water bath. After withdrawing the flask will be wiped with a minimum of handling. The pycnometer will be weighed after thermal equilibrium with the surrounding will have been established. Then the pycnometer will be filled with the test item. Care will be taken to avoid air bubbles when filling. The pycnometer will be immersed to the top of its neck in a water bath maintained at constant temperature and will be left in the bath for at least 20 min. The pycnometer will be removed from the bath. Afterwards the stopper will be immersed. The liquid on the neck will be removed with a piece of paper. Finally the top will be dried taking care not to withdraw liquid from the capillary and it will be weighed.

The test procedure will be repeated at least twice using independent test item samples.


Apparatus - Gas comparison pycnometer

Test Condition - 20 °C ± 1.0 °C

The sample cell will be weighed, filled with the test item and placed in the Multi-Pycnometer.

Afterwards the test will be performed. The procedure will be repeated until reproducible results are obtained. The sample cell containing test item will be reweighed to determine the mass of the tested test item.

At least two measurements performed.


The density [g/cm³] and the relative density at 20 °C will be reported.

Guidelines and Literature

  • Commission Regulation (EC) No 440/2008 laying down test methods pursuant to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) (originally published as Council Regulation (EC) No 440/2008, corrigendum according to Official Journal of the European Union (EN) dated June 3, 2008, L 143/55), Annex, Part A, A.3.: “Relative Density”, Official Journal of the European Union, L 142, Volume 51, 31 May 2008
  • Organisation for Economic Co-operation and Development (OECD), OECD Guidelines for Testing of Chemicals, Guideline No. 109, “Density of Liquids and Solids”, adopted October 02, 2012