{"id":1694,"date":"2025-11-20T17:35:40","date_gmt":"2025-11-20T17:35:40","guid":{"rendered":"https:\/\/pharmacoguide.com\/?p=1694"},"modified":"2025-11-20T17:35:40","modified_gmt":"2025-11-20T17:35:40","slug":"limit-test-for-colour-of-solution","status":"publish","type":"post","link":"https:\/\/pharmacoguide.com\/?p=1694","title":{"rendered":"Limit Test for Colour of solution"},"content":{"rendered":"

Title:<\/strong> Limit Test for Colour of solution<\/strong><\/em><\/span><\/h3>\n

 <\/p>\n

    \n
  1. Objective:<\/strong> Using identical test tubes of colourless, transparent, neutral glass with a flat base and an internal diameter of 15-25 mm, compare the liquid to be examined with a reference suspension.<\/li>\n<\/ol>\n

     <\/p>\n

      \n
    1. Principle: <\/strong>The\u00a0color of chemicals\u00a0is a\u00a0physical property<\/a>\u00a0of chemicals that in most cases comes from the\u00a0excitation of electrons<\/a>\u00a0due to absorption of energy performed by the chemical. What is seen by the eye is not the color absorbed, but the complementary color<\/a>\u00a0from the removal of the absorbed\u00a0wavelengths<\/a>.<\/li>\n<\/ol>\n

      \u00a0<\/strong><\/p>\n

      3. Procedure: <\/strong><\/p>\n

        \n
      • Preparation of Standard Solutions and Reagents:<\/strong><\/li>\n<\/ul>\n

        Note:<\/strong> All solutions should be prepared in Distilled\/Purified Water.<\/p>\n

          \n
        • 1M Sodium Thiosulphate Solution: <\/strong>Dissolve 25 g of Sodium Thiosulphate\u00a0 and 0.2 g of\u00a0 Sodium Carbonate in purified water and dilute to 1000 ml with the same solution.<\/li>\n
        • Starch Solution: <\/strong>Triturate (dissolve) 1 g of soluble Starch with 5 ml of water and add stirring continuously, to 100 ml of boiling water containing 10 mg of Mercuric Iodide.<\/li>\n
        • Sodium Hydroxide Solution<\/strong> (20% w\/v): <\/strong>Dissolve 20.0 g of Sodium Hydroxide in water and dilute to 100.0 ml with Purified water.<\/li>\n
        • Dilute Sulphuric acid: <\/strong>Dilute 57 ml of concentrated Sulphuric acid to 1000 ml with water.<\/li>\n
        • Hydrogen Peroxide solution (10 volume): <\/strong>Dilute Hydrogen Peroxide solution (20 volume) with an equal volume of water.<\/li>\n
        • Ferric Chloride Colorimetric Solution (FCS):\u00a0<\/strong> Dissolve about 46 g of Ferric Chloride Hexahydrate in enough of a mixture of 25 ml of concentrated Hydrochloric acid and 975 ml of water to produce 1000 ml. Pipette 10 ml of this solution into a 250-ml iodine flask, add 15 ml of water, 3 g of Potassium Iodide and 5 ml of concentrated Hydrochloric acid and allow the mixture to stand for 15 minutes. Dilute with 100 ml of water and titrate the liberated iodine with 0.1M Sodium Thiosulphate using 0.5 ml of Starch solution, added towards the end of the titration, as indicator. Perform a blank determination and make any necessary correction.<\/li>\n<\/ul>\n

          1 ml of\u00a00.1M Sodium Thiosulphate\u00a0is equivalent to 0.02703 g of FeCI3<\/sub>,6H2<\/sub>O (Ferric Chloride Hexahydrate). \u00a0Adjust the final volume of the solution by the addition of enough of the mixture of Hydrochloric acid and water so that each ml contains 0.045 g of FeCI3<\/sub>,6H2<\/sub>O.<\/p>\n

          Note:<\/strong> The solutions should be stored protected from light and standardised before use.<\/p>\n

          \u00a0<\/strong><\/p>\n

            \n
          • Cobaltous Chloride Colorimetric Solution (CCS):\u00a0<\/strong> Dissolve about 60 g of Cobaltous Chloride in enough of a mixture of 25 ml of concentrated Hydrochloric acid and 975 ml of water to produce 1000 ml. Pipette 5 ml of this solution into a 250 ml iodine flask, add 5 ml of Hydrogen Peroxide solution (10 volume) and 15 ml of Sodium Hydroxide solution, boil for 10 minutes, cool and add 2 g of Potassium Iodide and 60 ml of Dilute Sulphuric acid. Dissolve the precipitate by gentle shaking, if necessary, and titrate the liberated iodine with 1M Sodium Thiosulphate using 0.5 ml of Starch solution, added towards the pink end-point, as indicator. Carry out a blank titration and make any necessary correction.<\/li>\n<\/ul>\n

            Each ml of\u00a00.1M Sodium Thiosulphate\u00a0is equivalent to 0.02379 g of CoCl2<\/sub>,6H2<\/sub>O (Cobaltous Chloride). \u00a0Adjust the final volume of the solution by the addition of enough of the mixture of Hydrochloric acid and water so that each ml contains 0.0595g of CoCl2<\/sub>,6H2<\/sub>O.<\/p>\n

              \n
            • Cupric Sulphate Colorimetric Solution (CSS): <\/strong>Dissolve about 63 g of Cupric Sulphate in enough of a mixture of 25 ml of concentrated Hydrochloric acid and 975 ml of water to produce 1000 ml. Pipette 10 ml of this solution into a 250 ml iodine flask , add 40 ml of water, 4 ml of Acetic acid, 3 g of Potassium Iodide , and 5 ml of Hydrochloric acid and titrate the liberated iodine with 1M Sodium Thiosulphate\u00a0 using 0.5 ml of Starch solution, added towards the pale brown end-point, as indicator. Perform a blank determination and make any necessary correction.<\/li>\n<\/ul>\n

              Each ml of\u00a00.1M\u00a0Sodium Thiosulphate is equivalent to 0.02497g of CuSO4<\/sub>,5H2<\/sub>O (Cupric Sulphate). \u00a0Adjust the final volume of the solution by the addition of enough of the mixture Hydrochloric acid and water so that each ml contains 0.0624 g of CuSO4<\/sub>,5H2<\/sub>O.<\/p>\n

               <\/p>\n

                \n
              • Reference Solution:<\/strong>Prepare by mixing the volumes of\u00a0colorimetric solutions and Hydrochloric acid (1% w\/v HCl)\u00a0as indicated in Table No. 01.<\/li>\n<\/ul>\n

                Note:<\/strong> Reference solutions must be prepared immediately before use from the Colorimetric solutions which may be stored in Refrigerator.<\/p>\n

                \u00a0<\/strong><\/p>\n

                  \n
                • Method: <\/strong><\/li>\n<\/ul>\n

                  Transfer to a flat bottomed test tube of neutral glass 15 to 25 mm in diameter, a suitable volume of a liquid been examined such that the test tube is filled to a depth of 40 mm. Into another match test tube add the same volume of water or of the solvent used for preparing the solution being examined or of the\u00a0reference solution\u00a0stated in the individual monograph. Examine the colours of liquid in diffused light by viewing vertically against a white background.<\/p>\n

                  Colourless Solution:<\/strong>\u00a0<\/strong>A solution is considered\u00a0colourless\u00a0if it has the same appearance as\u00a0water\u00a0or the solvent used for preparing the solution or is not more intensely coloured than\u00a0Reference Solution BS8.<\/p>\n

                  Table No. 01<\/strong><\/p>\n\n\n\n\n
                  Colour of\u00a0 Reference
                  \nSolution<\/td>\n                  		Reference
                  \nsolution<\/td>\n                  		FCS
                  \n(ml)<\/td>\n                  		CCS
                  \n(ml)<\/td>\n                  		CSS
                  \n(ml)<\/td>\n                  		Hydrochloric Acid
                  \n(1% w\/v HCI) (ml)<\/td>\n<\/tr>\n
                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                  Yellow<\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                  Greenish\u00a0\u00a0 Yellow<\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                  Brownish\u00a0 Yellow<\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                  Brown<\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                  Red<\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/p>\n

                   <\/td>\n

                  		YS1<\/p>\n

                  YS2<\/p>\n

                  YS3<\/p>\n

                  YS4<\/p>\n

                  YS5<\/p>\n

                  YS6<\/p>\n

                  YS7<\/p>\n

                  GYS1<\/p>\n

                  GYS2<\/p>\n

                  GYS3<\/p>\n

                  GYS4<\/p>\n

                  GYS5<\/p>\n

                  GYS6<\/p>\n

                  GYS7<\/p>\n

                  BYS1<\/p>\n

                  BYS2<\/p>\n

                  BYS3<\/p>\n

                  BYS4<\/p>\n

                  BYS5<\/p>\n

                  BYS6<\/p>\n

                  BYS7<\/p>\n

                  BS1<\/p>\n

                  BS2<\/p>\n

                  BS3<\/p>\n

                  BS4<\/p>\n

                  BS5<\/p>\n

                  BS6<\/p>\n

                  BS7<\/p>\n

                  BS8<\/p>\n

                  RS1<\/p>\n

                  RS2<\/p>\n

                  RS3<\/p>\n

                  RS4<\/p>\n

                  RS5<\/p>\n

                  RS6<\/p>\n

                  RS7<\/td>\n

                  		24.0<\/p>\n

                  18.0<\/p>\n

                  12.0<\/p>\n

                  6.0<\/p>\n

                  3.2<\/p>\n

                  1.6<\/p>\n

                  0.8<\/p>\n

                  24.0<\/p>\n

                  14.5<\/p>\n

                  8.5<\/p>\n

                  5.0<\/p>\n

                  5.8<\/p>\n

                  2.9<\/p>\n

                  2.9<\/p>\n

                  24.0<\/p>\n

                  18.0<\/p>\n

                  12.0<\/p>\n

                  6.0<\/p>\n

                  3.0<\/p>\n

                  1.5<\/p>\n

                  1.0<\/p>\n

                  22.5<\/p>\n

                  15.0<\/p>\n

                  11.2<\/p>\n

                  7.5<\/p>\n

                  3.7<\/p>\n

                  1.5<\/p>\n

                  0.8<\/p>\n

                  0.4<\/p>\n

                  10.0<\/p>\n

                  7.5<\/p>\n

                  5.0<\/p>\n

                  3.8<\/p>\n

                  2.5<\/p>\n

                  1.3<\/p>\n

                  0.5<\/td>\n

                  		6.0<\/p>\n

                  4.5<\/p>\n

                  3.0<\/p>\n

                  1.5<\/p>\n

                  0.8<\/p>\n

                  0.4<\/p>\n

                  0.2<\/p>\n

                  0.5<\/p>\n

                  0.1<\/p>\n

                  0.05<\/p>\n

                  0.05<\/p>\n

                  0.05<\/p>\n

                  0.05<\/p>\n

                  0.05<\/p>\n

                  10.0<\/p>\n

                  7.5<\/p>\n

                  5.0<\/p>\n

                  2.5<\/p>\n

                  1.5<\/p>\n

                  0.8<\/p>\n

                  0.4<\/p>\n

                  22.5<\/p>\n

                  15.0<\/p>\n

                  11.2<\/p>\n

                  7.5<\/p>\n

                  3.7<\/p>\n

                  1.5<\/p>\n

                  0.8<\/p>\n

                  0.4<\/p>\n

                  20.0<\/p>\n

                  15.0<\/p>\n

                  10.0<\/p>\n

                  7.6<\/p>\n

                  5.0<\/p>\n

                  2.6<\/p>\n

                  1.0<\/td>\n

                  		0<\/p>\n

                  0<\/p>\n

                  0<\/p>\n

                  0<\/p>\n

                  0<\/p>\n

                  0<\/p>\n

                  0<\/p>\n

                  0.5<\/p>\n

                  0.1<\/p>\n

                  0.05<\/p>\n

                  0.05<\/p>\n

                  0.05<\/p>\n

                  0.05<\/p>\n

                  0.05<\/p>\n

                  4.0<\/p>\n

                  3.0<\/p>\n

                  2.0<\/p>\n

                  1.0<\/p>\n

                  0.5<\/p>\n

                  0.2<\/p>\n

                  0.1<\/p>\n

                  18.0<\/p>\n

                  12.0<\/p>\n

                  9.0<\/p>\n

                  6.0<\/p>\n

                  3.0<\/p>\n

                  1.2<\/p>\n

                  0.6<\/p>\n

                  0.2<\/p>\n

                  0<\/p>\n

                  0<\/p>\n

                  0<\/p>\n

                  0<\/p>\n

                  0<\/p>\n

                  0<\/p>\n

                  0<\/td>\n

                  		70.0<\/p>\n

                  77.5<\/p>\n

                  85.0<\/p>\n

                  92.5<\/p>\n

                  96.0<\/p>\n

                  98.0<\/p>\n

                  99.0<\/p>\n

                  75.0<\/p>\n

                  85.8<\/p>\n

                  91.4<\/p>\n

                  94.9<\/p>\n

                  194.1<\/p>\n

                  197.0<\/p>\n

                  397.0<\/p>\n

                  62.0<\/p>\n

                  71.5<\/p>\n

                  81.0<\/p>\n

                  90.5<\/p>\n

                  95.0<\/p>\n

                  97.5<\/p>\n

                  98.5<\/p>\n

                  37.0<\/p>\n

                  58.0<\/p>\n

                  68.6<\/p>\n

                  79.0<\/p>\n

                  89.6<\/p>\n

                  95.8<\/p>\n

                  97.8<\/p>\n

                  99.0<\/p>\n

                  70.0<\/p>\n

                  77.5<\/p>\n

                  85.0<\/p>\n

                  88.5<\/p>\n

                  92.5<\/p>\n

                  96.1<\/p>\n

                  98.5<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                   <\/p>\n

                  \n

                   <\/p>\n

                  “End of Document”<\/span><\/u><\/em><\/h4>\n","protected":false},"excerpt":{"rendered":"

                  Title: Limit Test for Colour of solution   Objective: Using identical test tubes of colourless, transparent, neutral glass with a flat base and an internal diameter of 15-25 mm, compare the liquid to be examined with a reference suspension.   Principle: The\u00a0color of chemicals\u00a0is a\u00a0physical property\u00a0of chemicals that in most cases comes from the\u00a0excitation of […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"templates\/template-full-width.php","format":"standard","meta":{"footnotes":""},"categories":[41],"tags":[],"class_list":["post-1694","post","type-post","status-publish","format-standard","hentry","category-elemental-impurities"],"_links":{"self":[{"href":"https:\/\/pharmacoguide.com\/index.php?rest_route=\/wp\/v2\/posts\/1694","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pharmacoguide.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/pharmacoguide.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/pharmacoguide.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/pharmacoguide.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1694"}],"version-history":[{"count":1,"href":"https:\/\/pharmacoguide.com\/index.php?rest_route=\/wp\/v2\/posts\/1694\/revisions"}],"predecessor-version":[{"id":1695,"href":"https:\/\/pharmacoguide.com\/index.php?rest_route=\/wp\/v2\/posts\/1694\/revisions\/1695"}],"wp:attachment":[{"href":"https:\/\/pharmacoguide.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1694"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pharmacoguide.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1694"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pharmacoguide.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1694"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}