No. of trials

Reagent volumes (mL)

Aqua-regia:H₂O₂

Digestion temperature (˚C)

Digestion time (min)

Observation

1

3:2

120

120

Deep Yellow

2

4:1

150

120

Deep Yellow

3

3:3

180

130

Deep Yellow

4

4:2

200

130

Deep Yellow

5

2:4

250

140

Yellow

6

5:1

270

150

Light yellow

7

6:1*

280*

150*

Clear colorless solution

8

5:2

300

180

Clear Colorless

9

6:2

310

200

Clear Colorless