ANNEXU.K.DETERMINATION OF DICHLOROMETHANE AND 1,1,1-TRICHLOROETHANE

IDENTIFICATION AND DETERMINATION OF MERCAPTOACETIC ACID IN HAIR-WAVING, HAIR-STRAIGHTENING AND DEPILATORY PRODUCTSU.K.

4.IDENTIFICATIONU.K.

4.1. Identification by spot tests U.K.

4.1.1. Reagents U.K.

All reagents should be of analytical purity.

4.1.1.1.Lead di(acetate) papes.U.K.

4.1.1.2.Hydrochloric acid solution (one volume of concentrated hydrochloric acid plus one volume of water)U.K.

4.1.2.ProcedureU.K.

4.1.2.1. Identification of mercaptoacetic acid by means of a colour reaction with lead di(acetate) U.K.

Place a drop of the sample to be analyzed on lead di(acetate) paper (4.1.1.1). If an intense yellow colour appears, mercaptoacetic acid is probably present.

Sensitivity: 0,5 %.

4.1.2.2. Characterization of inorganic sulphides by the formulation of hydrogen sulphide on acidification U.K.

Introduce, into a test tube, a few milligrams of the sample to be studied. Add 2 ml of distilled water and 1 ml of hydrochloric acid (4.1.1.2). Hydrogen sulphide, recognizable by its smell, is evolved and a black lead sulphide precipitate forms on the lead di(acetate) paper (4.1.1.1).

Sensitivity: 50 ppm.

4.1.2.3. Characterization of sulphites by the formation of sulphur dioxide upon acidification U.K.

Proceed as described in 4.1.2.2. Bring to the boil. The sulphur dioxide is recognizable by its smell and by its reducing properties in respect, for example, of permanganate ions.