ANNEX VIIITEST METHODS AND ANALYTICAL METHODS

2.Determination of anionic surfactants in biodegradability tests

2.2.Reagents and equipment

2.2.1.Buffer solution pH 10

Dissolve 24 g sodium bicarbonate, NaHCO3 AR, and 27 g anhydrous sodium carbonate (Na2CO3) AR in deionised water and dilute to 1 000 ml.

2.2.2.Neutral methylene blue solution

Dissolve 0,35 g methylene blue AR in deionised water and dilute to 1 000 ml. Prepare the solution at least twenty-four hours before use. The absorbency of the blank chloroform phase, measured against chloroform must not exceed 0,015 per 1 cm of layer thickness at 650 nm.

2.2.3.Acidic methylene blue solution

Dissolve 0,35 g methylene blue AR in 500 ml deionised water and mix with 6,5 ml H2SO4 (d = 1,84 g/ml). Dilute to 1 000 ml with deionised water. Prepare the solution at least twenty-four hours before use. The absorbency of the blank chloroform phase, measured against chloroform must not exceed 0,015 per 1 cm of layer thickness at 650 nm.

2.2.4.

Chloroform (trichloromethane) AR freshly distilled

2.2.5.

Dodecyl benzene sulphonic acid methyl ester

2.2.6.

Ethanolic potassium hydroxide solution, KOH 0,1 M

2.2.7.

Ethanol pure, C2H5OH

2.2.8.

sulphuric acid, H2SO4 0,5 M

2.2.9.

Phenolphthalein solution

Dissolve 1 g phenolphthalein in 50 ml ethanol and add 50 ml deionised water while stirring continuously. Filter off any precipitate obtained.

2.2.10.

Methanolic hydrochloric acid: 250 ml hydrochloric acid AR and 750 ml methanol

2.2.11.

Separating funnel, 250 ml

2.2.12.

Graduated flask, 50 ml

2.2.13.

Graduated flask, 500 ml

2.2.14.

Graduated flask, 1 000 ml

2.2.15.

Round-bottomed flask with ground glass stopper and reflux condenser, 250 ml; boiling granules

2.2.16.

pH meter

2.2.17.

Photometer for measurements at 650 nm, with 1 to 5 cm cells

2.2.18.

Qualitative grade filter paper