Preparation of Reagents and Buffers

Abstract

The water used in the preparation of reagents or buffers was either MilliQ or deionized double distilled water. Autoclaving was done by heating water to 121˚C at 15lbs for 20 minutes. A. Reagents for Determination of Na + ion Ammonium acetate was mixed in 800ml of water by adding 57ml of concentrated acetic acid and 68ml of concentrated ammonium hydroxide, this solution was diluted to a final volume of 1 litre. Standard sodium chloride solution was prepared by dissolving 2.338gm of sodium chloride in 10ml of 3N hydrochloric acid and diluted to 1 litre. Lithium chloride was prepared by dissolving 2.12gm of dry lithium chloride in water and diluted to exactly 1 litre. B. Reagents for determination of Ca ++ and Mg + ion Ammonium hydroxide buffer solution was prepared by dissolving 67.5gm of ammonium chloride in 570ml of concentrated ammonium hydroxide and diluted to 1 litre. Sodium hydroxide was prepared by dissolving 160gm sodium hydroxide and diluting to 1 litre. Standard calcium chloride solution was prepared by dissolving 0.5gm of pure calcium carbonate in 10ml of 3N hydrochloric acid and diluted to 1 litre. Eriochrome black T. indicator was prepared by dissolving 0.5gm of eriochrome black T (F241) and 4.5gm of hydroxylamine hydrochloride in 100ml of 95%ethanol. Ammonium pupurate indicator was prepared by mixing 0.5gm of ammonium purpurate with 100gm of powdered potassium sulphate. Versenate solution was prepared by dissolving 2gm of disodium dihydrogen ethylenediaminetetraacetate and 0.005gm of magnesium chloride hexahydrate in water and diluted to a volume of 1 litre. The solution was standardized, using each of the indicators eriochrome black T and ammonium pupurate, as the normality with ammonium pupurate was 3 to 5% higher than eriochrome black T. C. Cation Exchange Capacity 1M ammonium acetate (NH 4 OAc) saturating solution Diluted in a chemical hood, 57mL glacial acetic acid (99.5%) with ~800mL of distilled H 2 O in a 1 litre volumetric flask. Added 68mL of concentrated NH 4 OH, mixed and cooled. Adjusted the pH to 7.0 with NH 4 OH if needed.