68
5.
Do not proceed if
sulfuric acid is not
visible in the flask. Add
10 mL of 50% hydrogen
peroxide to the charred
sample via the funnel on
the fractionating
column.
Note: Do not heat to dryness.
Note: Visually confirm the
presence of sulfuric acid in
the flask before adding
hydrogen peroxide.
Note: If the digest does not
turn colorless, add 5 mL
incrementsof peroxide until
the digest becomes clear or
does not change color.
Note: If sample foams
during hydrogen peroxide
addition, stop the peroxide
flow and remove the
digestion flask and
fractionating column
(use finger cots). Cool for
30 seconds and return
apparatus to the heating
block. Start peroxide
addition with 2 mL,
then follow with the
remaining peroxide.
6. After addition of
hydrogen peroxide is
complete, boil off excess
hydrogen peroxide by
heating for one more
minute . Do not heat to
dryness.
Note: Ifthesamplegoesto
dryness, turn off the
Digesdahl and air cool to
room temperature. Add
water to flask before
handling. Repeat the
digestion from the
beginning using a new
sample.
7. Take the hot flask off
the heater and allow the
flask to air cool.
Remove the
fractionating column
from the digestion flask.
Note: Usefingercotsto
remove the digestion flask.
Placeitonacoolingpad
for at least
one minute.
Then remove the column.
Do not add water to the
flask until it has cooled.
8. Dilute the digest to
approximately 70 mL
with deionized water.
Note: Add deionized
water slowly at first. Cool
the flask if necessary
for handling.
DIGESTION PROCEDURE FOR SOLIDS, continued
网址：www.mamots.com 电话：0431-85178766
To Next Page
Loading...
