Chapter 2
Organic compounds in soils
Petroliation of hydrocarbons
2.1 HYDROCARBONS
2.1.1 Aliphatic hydrocarbons
Commonly used methods for the determination of petroleum hydrocarbons in soil are
modifications of the EPA method 418.1 which uses sonication or Soxhlet extraction
to separate the hydrocarbons from the soil prior to either infrared spectroscopy [1] or
gas chromatography with flame ionisation detection [2, 3].
Alternative methods have been sought for the assessment of contamination in
environmental samples that produce the need for the halogenated solvent commonly
used in methods for the determination of petroleum hydrocarbons in soil.
Supercritical fluid extraction with carbon dioxide has been shown to be an excellent alternative to conventional solvent extraction for the removal of hydrocarbons
pollutants from solid samples [4–7]. It is fast (∼30 minutes), non-polluting, and relatively simple to implement. Additionally, recent work has shown that supercritical
fluid extraction using carbon dioxide is generally applicable to soil samples that have
been contaminated with petroleum hydrocarbons ranging from those found in gasoline
to those in medium crude oil (i.e.
extraction mode or an off-line extraction mode. Off-line supercritical fluid extraction
is the most common mode and involves extracting the analytes from the matrix and
collecting in either a sorbent trap or a collection solvent [11]. Following the collection
step, the analytes are determined on a separate instrument for example, on a chromatograph or an infrared spectrometer). In the on-line supercritical fluid extraction
experiments, the outlet of the supercritical fluid extraction system is connected to a second analytical instrument [12–17]. This direct interface eliminated the need to collect
the extracted analytes in either a sorbent trap or a collection solvent. Consequently,
analyte loss is avoided and, more importantly, organic solvent use is eliminated.
Laing and Tilotta et al [5] have described the use of superficial argon for the
extraction of petroleum hydrocarbons from soil samples. Argon is an attractive solvent
because it is inexpensive and inert. Additionally, it has a clear spectral window in the
infrared region which makes it useful for on-line (i.e. directly coupled) experiments.
Organic compounds in soils
Petroliation of hydrocarbons
2.1 HYDROCARBONS
2.1.1 Aliphatic hydrocarbons
Commonly used methods for the determination of petroleum hydrocarbons in soil are
modifications of the EPA method 418.1 which uses sonication or Soxhlet extraction
to separate the hydrocarbons from the soil prior to either infrared spectroscopy [1] or
gas chromatography with flame ionisation detection [2, 3].
Alternative methods have been sought for the assessment of contamination in
environmental samples that produce the need for the halogenated solvent commonly
used in methods for the determination of petroleum hydrocarbons in soil.
Supercritical fluid extraction with carbon dioxide has been shown to be an excellent alternative to conventional solvent extraction for the removal of hydrocarbons
pollutants from solid samples [4–7]. It is fast (∼30 minutes), non-polluting, and relatively simple to implement. Additionally, recent work has shown that supercritical
fluid extraction using carbon dioxide is generally applicable to soil samples that have
been contaminated with petroleum hydrocarbons ranging from those found in gasoline
to those in medium crude oil (i.e.
extraction mode or an off-line extraction mode. Off-line supercritical fluid extraction
is the most common mode and involves extracting the analytes from the matrix and
collecting in either a sorbent trap or a collection solvent [11]. Following the collection
step, the analytes are determined on a separate instrument for example, on a chromatograph or an infrared spectrometer). In the on-line supercritical fluid extraction
experiments, the outlet of the supercritical fluid extraction system is connected to a second analytical instrument [12–17]. This direct interface eliminated the need to collect
the extracted analytes in either a sorbent trap or a collection solvent. Consequently,
analyte loss is avoided and, more importantly, organic solvent use is eliminated.
Laing and Tilotta et al [5] have described the use of superficial argon for the
extraction of petroleum hydrocarbons from soil samples. Argon is an attractive solvent
because it is inexpensive and inert. Additionally, it has a clear spectral window in the
infrared region which makes it useful for on-line (i.e. directly coupled) experiments.