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Releasing agents
Methods not shown do not use a releasing agent.
Method
Releasing agent
Cyanide-1
0.75 mL of 7.11 M sulfuric acid / 0.79 M magnesium
chloride solution
Cyanide-2
Cyanide-5
Cyanide-3 (WAD) 0.75 mL of 0.50 M zinc acetate/0.52 M sodium
acetate/0.87 M acetic acid
Sulfide-1
0.45 mL of 9.0 M sulfuric acid solution
Note: When an unknown matrix is initially distilled, identify
Sulfide-2
the amount of concentrated sulfuric acid necessary to
decrease the sample pH to 1 or less. The volume necessary
may be greater than 0.45 mL.
Prepare the releasing agent—Cyanide-1, -2 or -5
Makes 200 mL of releasing agent.
1. In a fume hood, put a 500 mL beaker on a top-loading balance.
2. Set the balance to zero.
3. Add 110.8 g of deionized water.
4. Add and fully dissolve 32.2 g of magnesium chloride hexahydrate (MgCl
5. Slowly add 139 g of concentrated sulfuric acid in increments of 40 g. Swirl and let cool between
additions.
6. Let the solution cool to ambient temperature.
7. Put the solution in a closed container.
Prepare the releasing agent—Cyanide-3 (WAD)
Makes 1 L of releasing agent.
1. In a fume hood, put a 1 L container on a top-loading balance.
2. Set the balance to zero.
3. Add 950 g of deionized water.
4. Add and fully dissolve 70.97 g of sodium acetate trihydrate (NaC
5. Add and fully dissolve 100 g of zinc acetate monohydrate (ZnC
6. Add 52.5 g of glacial acetic acid (C
7. Put the solution in a closed container.
Prepare the releasing agent—Sulfide-1 or -2
Makes 300 mL of releasing agent.
1. In a fume hood, put a 500 mL beaker on a top-loading balance.
2. Set the balance to zero.
3. Add 150 g of deionized water.
4. Slowly add 276 g of concentrated sulfuric acid in increments of 40 g. Swirl and let cool between
additions.
5. Let the solution cool to ambient temperature.
6. Put the solution in a closed container.
18 English
H
O
).
2
3
2
Preparation
Refer to
Prepare the releasing agent—
Cyanide-1, -2 or -5
on page 18.
Refer to
Prepare the releasing agent—
Cyanide-3 (WAD)
on page 18.
Refer to
Prepare the releasing agent—
Sulfide-1 or -2
on page 18.
· 6 H
O).
2
2
H
O
· 3 H
O).
2
3
2
2
H
O
· H
O).
2
3
2
2
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