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4.1 CLARITY OF SOLUTION

APPENDIX 4 PHYSICAL TESTS​

      4.1 CLARITY OF SOLUTION

      Use Method I unless otherwise directed.

Method I

      Into separate matched, flat-bottomed tubes of colourless, transparent, neutral glass, 15 to 20 mm in diameter, place sufficient of the test solution and of a suitable reference suspension, freshly prepared as specified below, such that the tubes are filled to a depth of 40 mm, accurately measured. Five minutes after preparation of the reference suspension, compare the contents of the tubes against a black background by viewing under diffused light down the vertical axes of the tubes. The diffusion of the light must be such that reference suspension I can be readily distinguished from water and from reference suspension II.

      Standard of opalescence Dissolve 1.0 g of hydrazine sulfate in sufficient water to produce 100.0 ml, and allow to stand for 4 to 6 hours. To 25.0 ml of this solution add a solution containing 2.5 g of methenamine in 25.0 ml of water, mix well and allow to stand for 24 hours. This suspension is stable for 2 months, provided that it is stored in a glass container free from surface defects.

      To prepare the standard of opalescence, dilute 15.0 ml of the suspension to 1000.0 ml with water. This suspension must be used within 24 hours of preparation.

      Reference suspensions Reference suspensions I to IV should be prepared as indicated in Table 1. Each suspension should be mixed well and shaken before use.

Table 1

      Expression of clarity and degree of opalescence

      A solution is termed clear if its opalescence is not more pronounced than that of reference suspension I.

      A solution is termed slightly opalescent if its opalescence is more pronounced than that of reference suspension I, but not more pronounced than that of reference suspension II.

      A solution is termed opalescent if its opalescence is more pronounced than that of reference suspension II, but not more pronounced than that of reference suspension III.

      A solution is termed very opalescent if its opalescence is more pronounced than that of reference suspension III, but not more pronounced than that of reference suspension IV.

Method II

      Use Procedure A or B as directed.

      Procedure A Into separate matched, flat-bottomed tubes of colourless, transparent, neutral glass, 12 mm in internal diameter, place 2.0 ml of the solution being examined and 2.0 ml of a suitable reference solution, freshly prepared as specified below. Five minutes after preparation of the reference solution, compare the contents of the tubes, in darkness, by passing laterally through the tubes a beam of light from an electric lamp giving a luminosity of 1000 lux at a distance of 1 m.

      Procedure B Into separate matched, flat-bottomed tubes of colourless, transparent, neutral glass, 16 mm in internal diameter, place 10.0 ml of the solution being examined and 10.0 ml of a suitable reference solution, freshly prepared as specified below. Five minutes after preparation of the reference solution, compare the contents of the tubes against a black background by viewing under diffused light down the vertical axes of the tubes.

      Expression of clarity and degree of opalescence

      A solution is termed clear if its appearance is the same as that of water, or of solvent used, or of the mixture of reagents in the absence of the test substance.

      A solution is termed very slightly opalescent if its opalescence is not more pronounced than that of reference solution A1 or B1.

      A solution is termed slightly opalescent if its opalescence is more pronounced than that of reference solution A1 or B1, but not more pronounced than that of reference solution A2 or B2.

      A solution is termed opalescent if its opalescence is more pronounced than that of reference solution A2 or B2, but not more pronounced than that of reference solution A3 or B3.

      A solution is termed very opalescent if its opalescence is more pronounced than that of reference solution Aor B3, but not more pronounced than that of reference solution A4 or B4.

      Reagents

      STANDARD CHLORIDE SOLUTION I Dilute 1.0 ml of 0.2 M sodium chloride with sufficient water to produce 100.0 ml.

      STANDARD CHLORIDE SOLUTION II Dilute 20.0 ml of standard chloride solution I with sufficient water to produce 100.0 ml.

      STANDARD CHLORIDE SOLUTION III Dilute 1.0 ml of standard chloride solution I with sufficient water to produce 100.0 ml.

      REFERENCE SOLUTIONS Reference solutions A1 to A4 and B1 to B4 should be prepared without vigorous shaking, as indicated in Table 2.

Table 2​

APPENDICES • 4.1 CLARITY OF SOLUTION
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หมายเหตุ / Note : TP II 2011 PAGE 419-420