Safety Considerations - Hach DR/700 Procedures Manual

Table 8. Digestion Guidelines for Specific Sample Types (continued)
Sample Sample
Type Weight
Edible 0.25 to 0.5 g
Oils
Ion equivalent
Exchange of 0.25 g
Resin dry resin
Soil 0.25 to 1.0 g
Fuels/ 0.25 to 0.5 g
Lubricants

SAFETY CONSIDERATIONS

Digesdahl Digestion Apparatus
For safe Digesdahl operation:
•Sample size-Never exceed 0.5 grams of sample (dry weight)
•Oils and organic liquids should be considered as solids when
determining sample size.
•Acid type- Only use acid specified in Hach step-by-step procedures.
•Acid volume- Never use less than 3 mL.
•Always follow the order of steps indicated.
Amount Preheat
of Acid Time
4-6 mL 4 min.
10 -15 mL 12 min.
6 mL 4 min.
6 mL 4 min.
1-44
Amount of Special
Peroxide Instructions
5 mL Weigh sample into
immediately flask and record
and 5 mL exact weight.
later
20 mL Digest will be clear
with particles on
bottom if metal
oxides are not
soluble in H
Add aqua regia or
suitable solvent to
dissolve particles.
If particles are
floating, start again
using 15 mL H
and longer char
time.
10 to 20 mL
20 mL Heat the diluted
digest for 15
minutes and filter.
Temperature of
heater may need to
be lowered slightly
if foaming or
burning occur.
SO .
2 4
SO
2 4