A: To 1mLof a saturated solution of it add 1mLof nitric acid:a light red color appears.

B: To 1mLof a saturated solution of it add 1mLof bromine TS:a yellow,flocculent precipitate is formed.Add 2mLof 6Nammonium hydroxide:the precipitate dissolves,producing a yellow solution.

Standard preparation— Transfer 34.0mg of mercuric chloride to a 250-mLvolumetric flask.Add 1drop of hydrochloric acid,add water to dissolve,and dilute with water to volume.Transfer 1.0mLof this solution to a 100-mLvolumetric flask,add 1drop of hydrochloric acid,and dilute with water to volume.Transfer 1.0mLof this solution to a 500-mLvolumetric flask,add 1drop of hydrochloric acid,and dilute with water to volume.

Test preparation— Transfer 134mg to a 250-mLbeaker,and cautiously add 10mLof 11Nnitric acid and 10mLof 18Nsulfuric acid.Digest,with the aid of heat,in a well-ventilated hood until the evolution of brown fumes ceases.Cautiously add an additional 10mLof 11Nnitric acid,and continue heating until no more fumes are evolved.Cool,transfer to a 200-mLvolumetric flask,and dilute with water to volume.

Procedure— Transfer 100mLof Standard preparationto a 300-mLmercury analysis reaction vessel,add 2drops of potassium permanganate solution (1in 20),and mix (the solution should be purple;add additional permanganate solution dropwise,if necessary).Add 5mLof 11Nnitric acid,stir,and allow to stand for not less than 15seconds.Add 5mLof 18Nsulfuric acid,stir,and allow to stand for not less than 45seconds.Add 5mLof hydroxylamine hydrochloride solution (3in 200),stir,and allow to stand until the solution turns light yellow or colorless.Add 5mLof stannous chloride solution (1in 10)[NOTE—Disregard the presence of insoluble matter in this solution;mix prior to use],immediately insert the aerator connected to the air pump,and determine the maximum absorbance of the treated Standard preparationat the mercury resonance line of 253.65nm,with a suitable atomic absorption spectrophotometer equipped with a mercury hallow-cathode lamp and an absorption cell that permits the flameless detection of mercury.Connect in a closed system with a circulating air pump,a calcium chloride drying tube,and an aerator inserted in a 300-mLreaction vessel so that air passed through the treated preparation contained in the reaction vessel evaporates any metallic mercury present.In a similar manner,treat 100mLof the Test preparationand 100mLof water (reagent blank),and determine the maximum absorbances at the same wavelength [NOTE—Check the zero setting of the instrument frequently].The absorbance of the solution from the Test preparationdoes not exceed that of the solution from the Standard preparation(3ppm).