23
Table 1 Digestion Guidelines of Specific Sample Types
Sample
Type
Sample Weight
Vol. of
Acid
Preheat
Time
(Step 5)
Vol. of
Peroxide
Special Instructions
Plant tissue 0.25 to 0.5 g 4 mL 4 min. 10 mL Use Nitrogen-free paper to
weigh samples.
Meat &
Poultry
0.5gor
predigestion
4mLorasin
predigest
4min. 10mL —
Fluid
Fertilizers
0.1 to 0.25 g 4 mL 4 min. 10 mL Add 0.4 g Kjeldahl Reduction
Powder to flask before adding
sulfuric acid. Place the flask in
an 80 °C oven 15 minutes before
digestion. Use N-free paper to
weigh samples.
Feed &
Forage
0.25 g 4 mL 4 min. 10 mL —
Dairy 0.25to2.0g 4mL 4min. 10mL —
Cereal 0.25 to 0.5 g 4 mL 4 min. 10 mL Use Nitrogen-free paper to
weigh samples.
Beverage about 5 g
(pipet into funnel
4 mL 1 min. 10 mL Preheat acid for 1 minute then
add sample through funnel. Heat
flask for 30 seconds after sample
is in the flask.
Sludge <2.5 g wet sludge
<0.5 g dried sludge
4 mL 3-5 min. 10 mL of
increase in 5
mL increments
Heat the diluted digest for 15
minutes and filter.
Water &
Wastewater
not more than 0.5 g
solid (mL = 40/C;
C= % solids)
3mL untilacid
is refluxing
10 mL or
increase in 5
mL increments
Water must evaporate before
acid will reflux. Boiling chips
required.
Bath
Solutions
0.3 to 10 mL 4 mL 4 min. 10 mL Water must evaporate before
acid will reflux. Boiling chips
required.
Edible Oils 0.25 to 0.5 g 4-6 mL 4 min. 5 mL
immediately
and 5 mL later
Weigh samples into flake and
record exact weight.
Ion
Exchange
Resins
equivalent of 0.25 g
dry resin
10-15 mL 12 min. 20 mL Digest will be clear with particles
on bottom if metal oxides are not
solubleinH
2
SO
4
. Add aqua
reagia or suitable solvent to
dissolve particles. If particles are
floating, start again using 15 mL
H
2
SO
4
and longer char time.
Soil 0.25 to 0.5 g 6 mL 4 min. 10-20 mL —
Fuels 0.25 to 0.5 g 6 mL 4 min. 20 mL Heat the diluted digest for 15
min. and filter. Lower heater
temperature if foaming or
burning occurs.
网址：www.mamots.com 电话：0431-85178766
To Next Page
Loading...
