美国药典USP32 重金属part 中文翻译Word格式.docx

1、Special Reagents Lead Nitrate Stock Solution Dissolve 159.8 mg of lead nitrate in 100 mL of water to which has been added 1 mL of nitric acid, then dilute with water to 1000 mL. Prepare and store this solution in glass containers free from soluble lead salts.Standard Lead Solution On the day of use,

2、 dilute 10.0 mL of Lead Nitrate Stock Solution with water to 100.0 mL. Each mL of Standard Lead Solution contains the equivalent of 10 g of lead. A comparison solution prepared on the basis of 100 L of Standard Lead Solution per g of substance being tested contains the equivalent of 1 part of lead p

3、er million parts of substance being tested.Method I pH 3.5 Acetate Buffer Dissolve 25.0 g of ammonium acetate in 25 mL of water, and add 38.0 mL of 6 N hydrochloric acid. Adjust, if necessary, with 6 N ammonium hydroxide or 6 N hydrochloric acid to a pH of 3.5, dilute with water to 100 mL, and mix.

4、Standard Preparation Into a 50-mL color-comparison tube pipet 2 mL of Standard Lead Solution （20 g of Pb）, and dilute with water to 25 mL. Using a pH meter or short-range pH indicator paper as external indicator, adjust with 1 N acetic acid or 6 N ammonium hydroxide to a pH between 3.0 and 4.0, dilu

5、te with water to 40 mL, and mix. Test Preparation Into a 50-mL color-comparison tube place 25 mL of the solution prepared for the test as directed in the individual monograph; or, using the designated volume of acid where specified in the individual monograph, dissolve in and dilute with water to 25

6、 mL the quantity, in g, of the substance to be tested, as calculated by the formula: 2.0/（1000L）, in which L is the Heavy metals limit, as a percentage. Using a pH meter or short-range pH indicator paper as external indicator, adjust with 1 N acetic acid or 6 N ammonium hydroxide to a pH between 3.0

7、 and 4.0, dilute with water to 40 mL, and mix. Monitor Preparation Into a third 50-mL color-comparison tube place 25 mL of a solution prepared as directed for Test Preparation, and add 2.0 mL of Standard Lead Solution. Using a pH meter or short-range pH indicator paper as external indicator, adjust

8、with 1 N acetic acid or 6 N ammonium hydroxide to a pH between 3.0 and 4.0, dilute with water to 40 mL, and mix. , Procedure To each of the three tubes containing the Standard Preparation, the Test Preparation, and the Monitor Preparation, add 2 mL of pH 3.5 Acetate Buffer, then add 1.2 mL of thioac

9、etamideglycerin base TS, dilute with water to 50 mL, mix, allow to stand for 2 minutes, and view downward over a white surface *: the color of the solution from the Test Preparation is not darker than that of the solution from the Standard Preparation, and the color of the solution from the Monitor

10、Preparation is equal to or darker than that of the solution from the Standard Preparation. NOTEIf the color of the Monitor Preparation is lighter than that of the Standard Preparation, use Method II instead of Method I for the substance being tested. Method II NOTEThis method does not recover mercur

11、y. pH 3.5 Acetate Buffer Prepare as directed under Method I. Standard Preparation Pipet 4 mL of the Standard Lead Solution into a suitable test tube, and add 10 mL of 6 N hydrochloric acid. Test Preparation Use a quantity, in g, of the substance to be tested as calculated by the formula: 4.0/（1000L）

12、, in which L is the Heavy metals limit, as a percentage. Transfer the weighed quantity of the substance to a suitable crucible, add sufficient sulfuric acid to wet the substance, and carefully ignite at a low temperature until thoroughly charred. （The crucible may be loosely covered with a suitable

13、lid during the charring.） Add to the carbonized mass 2 mL of nitric acid and 5 drops of sulfuric acid, and heat cautiously until white fumes no longer are evolved. Ignite, preferably in a muffle furnace, at 500 to 600, until the carbon is completely burned off （no longer than 2 hours）. If carbon rem

14、ains, allow the residue to cool, add a few drops of sulfuric acid, evaporate, and ignite again. Cool, add 5 mL of 6 N hydrochloric acid, cover, and digest on a steam bath for 10 minutes. Cool, and quantitatively transfer the solution to a test tube. Rinse the crucible with a second 5-mL portion of 6

15、 N hydrochloric acid, and transfer the rinsing to the test tube. Monitor Preparation Pipet 4 mL of the Standard Lead Solution into a crucible identical to that used for the Test Preparation and containing a quantity of the substance under test that is equal to 10% of the amount required for the Test

16、 Preparation. Evaporate on a steam bath to dryness. Ignite at the same time, in the same muffle furnace, and under the same conditions used for the Test Preparation. Cool, add 5 mL of 6 N hydrochloric acid, cover, and digest on a steam bath for 10 minutes. Cool, and quantitatively transfer to a test

17、 tube. Rinse the crucible with a second 5-mL portion of 6 N hydrochloric acid, and transfer the rinsing to the test tube. Procedure Adjust the solution in each of the tubes containing the Standard Preparation, the Test Preparation, and the Monitor Preparation with ammonium hydroxide, added cautiousl

18、y and dropwise, to a pH of 9. Cool, and adjust with glacial acetic acid, added dropwise, to a pH of 8, then add 0.5 mL in excess. Using a pH meter or short-range pH indicator paper as external indicator, check the pH, and adjust, if necessary, with 1 N acetic acid or 6 N ammonium hydroxide to a pH b

19、etween 3.0 and 4.0. Filter, if necessary, washing the filter with a few mL of water, into a 50-mL color-comparison tube, and then dilute with water to 40 mL. Add 2 mL of pH 3.5 Acetate Buffer, then add 1.2 mL of thioacetamideglycerin base TS, dilute with water to 50 mL, mix, allow to stand for 2 min

20、utes, and view downward over a white surface*: the color of the solution from the Test Preparation is not darker than that of the solution from the Standard Preparation, and the color of the solution from the Monitor Preparation is equal to or darker than that of the solution from the Standard Prepa

21、ration. NOTEIf the color of the solution from the Monitor Preparation is lighter than that of the solution from the Standard Preparation, proceed as directed for Method III for the substance being tested. Method III Standard Preparation Transfer a mixture of 8 mL of sulfuric acid and 10 mL of nitric

22、 acid to a clean, dry, 100-mL Kjeldahl flask, and add a further volume of nitric acid equal to the incremental volume of nitric acid added to the Test Preparation. Heat the solution to the production of dense, white fumes; cool; cautiously add 10 mL of water; and, if hydrogen peroxide was used in tr

23、eating the Test Preparation, add a volume of 30 percent hydrogen peroxide equal to that used for the substance being tested. Boil gently to the production of dense, white fumes. Again cool, cautiously add 5 mL of water, mix, and boil gently to the production of dense, white fumes and to a volume of

24、2 to 3 mL. Cool, dilute cautiously with a few mL of water, add 2.0 mL of Standard Lead Solution （20 g of Pb）, and mix. Transfer to a 50-mL color-comparison tube, rinse the flask with water, adding the rinsing to the tube until the volume is 25 mL, and mix. Test Preparation Unless otherwise indicated

25、 in the individual monograph, use a quantity, in g, of the substance to be tested as calculated by the formula: 2.0/（1000L）, in which L is the Heavy metals limit, as a percentage. If the substance is a solid Transfer the weighed quantity of the test substance to a clean, dry, 100-mL Kjeldahl flask.

26、NOTEA 300-mL flask may be used if the reaction foams excessively. Clamp the flask at an angle of 45, and add a sufficient quantity of a mixture of 8 mL of sulfuric acid and 10 mL of nitric acid to moisten the substance thoroughly. Warm gently until the reaction commences, allow the reaction to subsi

27、de, and add portions of the same acid mixture, heating after each addition, until a total of 18 mL of the acid mixture has been added. Increase the amount of heat, and boil gently until the solution darkens. Cool, add 2 mL of nitric acid, and heat again until the solution darkens. Continue the heati

28、ng, followed by addition of nitric acid until no further darkening occurs, then heat strongly to the production of dense, white fumes. Cool, cautiously add 5 mL of water, boil gently to the production of dense, white fumes, and continue heating until the volume is reduced to a few mL. Cool, cautiously add 5 mL of water, and examine the color of the solution. If the color is yellow, cautiously add 1 mL of 30 percent hydrogen peroxide, and again evaporate to the