CO2_2016 - page 20

18
Chimica Oggi - Chemistry Today
- vol. 34(2) March/April 2016
analysis followed the standard method of sieves (13). The
solvents employed were dichloromethane, n-hexane/
acetone, hexane / acetone, anhydrous sodium sulfate
and silica gel 60 (70-230 mesh ASTM) was of analytical
grade; neutral alumina type 507 (70-290 mesh ASTM) and
the extraction of cellulose cartridges of 20 mm in diameter
and 80 mm long. The silica, alumina and anhydrous
sodium sulfate were activated at 400 °C for 4 hours. The
aluminum sheets were rinsed with acetone and dried at
room temperature before use.
Copper needles Sigma-Aldrich were activated with
concentrated hydrochloric acid and after washing with
purified water (twice), methanol (twice), dichloromethane
(twice) and hexane (twice), were stored in hexane.
PAHs standards were (Naphthalene, Acenaphthene,
Acenaphthylene, Fluorene, Phenanthrene, Anthracene,
Fluoranthene, Pyrene, Benzo [a] anthracene, Chrysene,
Benzo [b] fluoranthene, Benzo [k] fluoranthene, Benzo [a]
pyrene, Indeno [123cd] pyrene Dibenzo [ah] anthracene,
Benzo [ghi] perylene.
To determine the performance of extraction, a mass
of 20 g received sediment addition of 100 ul of PAHs
mixture of deuterated standards (Phenanthrene D10, D12
and Chrysene Perylene D12) at 20 mg.l
-1
for subsequent
determination of recovery process. The study was done in
triplicate.
The extraction of the analytes was performed using
Soxhlet equipment, according to EPA 3540 method (14),
20 g of the wet sample was mixed with 20 g of anhydrous
sodium sulfate. The extraction was for 16 hours using
about 250 ml of a mixture solvent of acetone / hexane
(1:1, v/v). Needles copper activated were added during
the extraction for removal of sulfur in order to avoid
interference of this element in the gas chromatography
analysis. The extracts were conducted through a column
filled with anhydrous sodium sulfate and concentrated
under a stream of nitrogen 99.99%.
Fractionation of the extracts was
performed using column with 1 g
anhydrous sodium sulfate; 3.2 g silica
5% off; 1.8 g of alumina 2% disabled
and 1 g of anhydrous sodium sulfate
on top. The extracts were mixed with
0.5 g of silica and added to the top of
column. The sequence of solvents for
the elution followed the order: 20 ml
of n-hexane to obtain the F1 fraction
(aliphatic); 20 ml of a n-hexane / DCM
solution (1:5 v/v) and DCM solution
20 mL / hexane (1:1 v/v) to obtain
the F2 fraction (polycyclic aromatic
compounds) resulting from the mixing
of the two fractions later (15). All
fractions were concentrated under
a stream of nitrogen and stored at
-4
o
C. Fractions were controlled by
gravimetry. The mass fraction of 1
quantified the aliphatic content and
the sum of fractions 1 and 2 quantified
the total petroleum hydrocarbons
(HTP). For the chromatographic
analysis, fractions (F1 and F2) were
reconstituted to 1 ml in DCM.
Only a fraction F2 was considered in
Pepino Channel (B), São Francisco de Paula Channel (C)
and the São Gonçalo Channel on the Figure 1 and Table 2.
They received over urban drainage runoff from various points,
from parking lots, paved streets, commercial buildings and
residential, to part of the countryside, travels flow towards the
São Gonçalo Channel. Therefore, ten samples were collected
from surface sediments (0-5 cm) using a stainless steel dredge
type Van Veen.
The samples were placed in August 2014 (winter) in clean
containers with solvent and wrapped with aluminum foil,
homogenized, frozen immediately temperature -4 °C until
analysis.
Sediment sXamples were taken and collected for
determination of water content, total organic matter (TOM)
was determined by ashing method≤ (11,12) and particle size
Figure 1.
Location of sampling points.
The georeferencing was determined by GPS measurements
(GPS, Global Positioning System, equipment Garmin & Etrex®,
to ± 15 m).
Table 2.
Description of the collection points and coordinates.
1...,10,11,12,13,14,15,16,17,18,19 21,22,23,24,25,26,27,28,29,30,...68
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