Arsenic Test For Glass Container | Arsenic Test For Container Procedure | USP General Chapter 660 Containers – Glass |
Arsenic Test For Glass Container Procedures :
Test Solution Preparation :
Cleaning: Remove any debris or dust. Shortly before the test. rinse each container carefully at least twice with Purified Water, refilled, and allow to stand. Immediately before testing, empty the containers; rinse once with Purified Water, then with carbon dioxide-free water; and allow to drain. Complete the cleaning procedure from the first rinsing within 20-30 min. Closed ampules may be warmed in a water bath or in an air oven at about 40° for approximately 2 min before opening to avoid container pressure when opening. Do not rinse before testing.
Filling and heating: The containers are filled with carbon dioxide-free water up to the filling volume. Containers in the form of cartridges or prefillable syringes are closed in a suitable manner with material that does not interfere with the test. Each container, including ampuls, shall be loosely capped with an inert material such as a dish of neutral glass or aluminum foil previously rinsed with Purified Water. Place the containers on the tray of the autoclave. Place the tray in an autoclave containing a quantity of water such that the tray remains clear of the water. Close the autoclave, and carry out autoclaving procedure steps 1-8 as described in the Glass Grains Test, except that the temperature is maintained at 121° ± 1° for 60 ± 1 min. If a water bath is used for cooling samples, take care that the water does not make contact with the loose foil caps to avoid contamination of the extraction solution.
The apparatus (see illustration) consists of an arsine generator (a) fitted with a scrubber unit (c) and an absorber tube
(e) with standard-taper or ground glass ball-and-socket joints (b and d) between the units. However, any other suitable apparatus, embodying the principle of the assembly described and illustrated, may be used.
Method I
Solution preparation :
2 N Sulfuric Acid : Transfer 56.2 mL of sulfuric acid to a 1000-mL volumetric flask containing about 500 mL of water. Cool and dilute with water to volume.
Potassium iodide TS : Dissolve 16.5 g of potassium iodide in water to make 100 ml. Store in light-resistant containers.
Stannous Chloride, Acid, Stronger, TS : Dissolve 40 g of stannous chloride in I00 ml of hydrochloric acid. Store in glass containers, and use within 3 months.
Silver Diethyldithiocarbamate TS : Dissolve 1 g of silver diethyldithiocarbamate in 200 mL of pyridine from a freshly opened bottle or that which has been recently distilled. Store in light-resistant containers, and use within 30 days.
Arsenic Trioxide Stock Solution: Dissolve 132.0 mg of arsenic trioxide, previously dried at 105° C for 1 hour and accurately weighed, in 5 mL of sodium hydroxide solution (1 in 5) in a 1000-mL volumetric flask. Neutralize the solution with 2 N sulfuric acid, add 10 mL more of 2 N sulfuric acid, then add recently boiled and cooled water to volume, and mix.
Standard Arsenic Solution: Transfer 10.0 mL of Arsenic Trioxide Stock Solution to a 1000-mL volumetric flask, add 10 mL of 2 N sulfuric acid, then add recently boiled and cooled water to volume, and mix. Each mL of Standard Arsenic Solution contains the equivalent of 1 ug of arsenic (As). Keep this solution in an all-glass container, and use within 3 days.
Standard Preparation: Pipet 3.0 mL of Standard Arsenic Solution into a generator flask, and dilute with water to 35 ml.
Test Preparation: 35 mL of the water from one Type I or Type II glass container or, in the case of smaller containers, 35 mL of the combined contents of several Type I or Type II glass containers, prepared as above in test solution preparation.
Procedure: Treat the Standard Preparation and the Test Preparation similarly as follows.
Add 20 mL of 7 N sulfuric acid, 2 mL of potassium iodide TS, 0.5 mL of stronger acid stannous chloride TS, and 1 mL of isopropyl alcohol, and mix.
Allow to stand at room temperature for 30 minutes. Pack the scrubber tube (c) with two pledgets of cotton that have been soaked in saturated lead acetate solution, freed from excess solution by expression, and dried in vacuum at room temperature, leaving a 2-mm space between the two pledgets. Lubricate the joints (b and d) with a suitable stopcock grease designed for use with organic solvents, and connect the scrubber unit to the absorber tube (e).
Transfer 3.0 mL of silver diethyldithiocarbamate TS to the absorber tube. Add 3.0 g of granular zinc (No. 20 mesh) to the mixture in the flask, immediately connect the assembled scrubber unit, and allow the evolution of hydrogen and the color development to proceed at room temperature for 45 minutes, swirling the flask gently at 10-minute intervals. Disconnect the absorber tube from the generator and scrubber units, and transfer the absorbing solution to a 1-cm absorption cell.
Results : Any red color produced by the Test Preparation does not exceed that produced by the Standard Preparation. If necessary or desirable, determine the absorbance at the wavelength of maximum absorbance between 535 and 540 nm, with a suitable spectrophotometer or colorimeter, using silver diethyldithiocarbamate TS as the blank.
Interfering Chemicals: Metals or salts of metals, such as chromium, cobalt, copper, mercury, molybdenum, nickel, palladium, and silver, may interfere with the evolution of arsine. Antimony, which forms stibine, produces a positive interference in the color development with silver diethyldithiocarbamate TS; when the presence of antimony is suspected, the red colors produced in the two silver diethy dithiocarbamate solutions may be compared at the wavelength of maximum absorbance between 535 and 540 mm, with a suitable colorimeter, since at this wavelength the interference due to stibine is negligible.
Also read : USP General Chapter 660 Containers – Glass
