EAVY METALS determination 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. Standard Lead Solution— On the day of use, dilute 10.0 mL of Lead Nitrate Stock Solution with water to 100.0 mL. Each mL of Standard Lead Solution contains how many µg of lead? Standard Preparation— Into a 50-mL color-comparison tube pipet 2 mL of Standard Lead Solution, and dilute with water to 40 mL, and mix. Test Preparation— Into a 50-mL color-comparison tube dissolve 1.0g ascorbic acid (mol wt 176.12) in 25 mL of water, dilute with water to 40 mL, and mix. Procedure— To each of the two tubes containing the Standard Preparation, the Test Preparation, add 2 mL of pH 3.5 Acetate Buffer, then add 1.2 mL of thioacetamide–glycerin base TS, dil
HEAVY METALS determination
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.
Standard Lead Solution— On the day of use, dilute 10.0 mL of Lead Nitrate Stock Solution with water to 100.0 mL.
Each mL of Standard Lead Solution contains how many µg of lead?
Standard Preparation— Into a 50-mL color-comparison tube pipet 2 mL of Standard Lead Solution, and dilute with water to 40 mL, and mix.
Test Preparation— Into a 50-mL color-comparison tube dissolve 1.0g ascorbic acid (mol wt 176.12) in 25 mL of water, dilute with water to 40 mL, and mix.
Procedure— To each of the two tubes containing the Standard Preparation, the Test Preparation, add 2 mL of pH 3.5 Acetate Buffer, then add 1.2 mL of thioacetamide–glycerin 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. The colour is formed when thioacetamide reacts with what?
Calculate the Limit (% wt/wt)
| a. |
None of these answers. |
|
| b. |
0.003 |
|
| c. |
0.004 |
|
| d. |
0.02 |
|
| e. |
0.04 |
|
| f. |
0.002 |
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