Agriculture Reference
In-Depth Information
PROBLEMS
7.1.
What type of extractant would you chose to extract the following com-
pounds from soil? Explain the rationale for your choice.
(a) LiCl
(b) CH
3
CH
2
OH
(c) CH
3
(CH
2
)
10
CH
3
7.2.
List the different “grades” of water available and describe how they are
different and what residual materials they might contain.
7.3.
A 100-g soil sample from the field was dried overnight at 105°C and later
was found to have a weight of 95 g. Calculate the percent moisture on a
dry-weight bases [see Chapter 4, equations (4.3) and (4.4)].
7.4.
A researcher develops an extraction-cleanup procedure using a sandy
soil. The procedure works well and is reported in the literature. Another
researcher uses the same procedure on a clayey soil and an organic soil
and obtains very poor, inconsistent results. What factors might account
for these results? (You might want to use information from previous
chapters to help answer this question.)
7.5.
Describe in detail two extraction procedures applied to soil. (You might
want to consult some of the references in the bibliography to answer this
question.)
7.6.
Describe two cleanup methods and list the advantages and disadvan-
tages of each.
7.7.
Explain why drying soil is both an important and a difficult procedure.
Explain why all nonaqueous soil extracts may need to be dried. (You
will need to consult previous chapters to answer this question.)
7.8.
Can solid-phase extraction be used to concentrate an extract?
7.9.
Using alcohol in ether as an example, explain why the stabilizers added
to solvents may cause a problem in an extraction procedure.
7.10.
What are the similarities between hexanes and petroleum ether? How
do their characteristics affect chromatographic analysis? (You might
want to consult Chapter 9 in answering this question.)
BIBLIOGRAPHY
Chulsung K, Lee Y, Ong SK. Factors affecting EDTA extraction of lead form lead-
contaminated soils.
Chemosphere
51
:845-853, 2003.
