Reference method for measuring releases of mercury from mercury cell chlor-alkali plants: section 5

Water: Deionized or distilled water.
Sulphuric Acid (CAUTION: Wear protective eyewear): Prepare a 20% (v/v) solution by slowly adding 208 mL of concentrated sulphuric acid (H ₂SO ₄) to 750 mL of cooled distilled water. Stir slowly with continued cooling and dilute to a final volume of 1 L at ambient temperature.
Acid Permanganate Absorbing Solution: Prepare 2% (w/v) potassium permanganate (KMnO ₄) in 10% (v/v) sulphuric acid solution by dissolving 20 g of reagent-grade potassium permanganate in 500 mL of 20% sulphuric acid and diluting to a final volume of 1 L. Prepare the amount required for one day's sampling. Place in an amber glass bottle and store in a cool, dark place. Do not keep this reagent more than one day.
Cleaning Solution. (CAUTION: Wear protective eyeware): Clean glassware prior to use with a solution prepared by slowly adding 35 mL of saturated potassium dichromate (K ₂Cr ₂O ₇) to 1 L of concentrated sulphuric acid. This solution should be cooled during preparation.
Silica Gel: Indicating type, 6 to 16 mesh, dried at 175°C for 2 h.

Water: Deionized or distilled water is required.
Hydroxylamine Hydrochloride: Prepare a 15% (w/v) aqueous solution by dissolving 15g of reagent-grade hydroxylamine hydrochloride (NH ₂OH·HCl) in 80 mL of water and diluting to 100 mL with distilled water. Store in a wash bottle.
Stock Mercury Standard: Stock mercury solutions can be purchased commercially or prepared from mercury salts. A solution made by dissolving 1.3535 g of mercuric chloride HgCl ₂ (poisonous) in 50 mL concentrated nitric acid (HNO ₃) and diluting to 1 L contains 1000 ppm mercury. This reagent, when stored in a glass container, can be considered stable for at least three months.
Intermediate Mercury Standard: Prepare a 10 ppm mercury standard in 1 % (v/v) nitric acid by diluting 1 mL of the stock mercury standard to 100 ml with 1% (v/v) nitric acid. This reagent is stable for one week.
Sulphuric Acid. (CAUTION: Wear protective eyeware): Prepare a 2N solulion by slowly adding 56 mL of concentrated sulphuric acid (H ₂SO ₄) to 900 mL of cooled water. Stir slowly with continued cooling and dilute to a final volume of 1 L at ambient temperature.
Stannous Chloride: Prepare fresh daily a 10% (w/v) solution of stannous chloride (SnCl ₂) in 2N sulphuric acid by dissolving 10 g of stannous chloride in 80 mL of 2N sulphuric acid and making up to 100 mL with 2N sulphuric acid.

NOTE: All reagents should be mercury free.

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