The adsorbing cartridge used in this study was a stainless steel
cylinder 5.8 mm in diameter with 100 mesh grid opening, packed
with 530 mg activated charcoal of 35–50 mesh particle size.
Four Radiello diffusive samplers were placed in each of the
tanks; two of the samples were extracted with carbon disulphide
as suggested in the Radiello manual, and the rest were extracted
with hexadecane, to be able to measure the most volatile compounds,
including the carbon disulphide. Hexadecane is employed
as extraction solvent by U.S. Environmental Protection Agency in
Method 3820 (USEPA, 1986). Hexadecane was employed due to
its high boiling point, it is a non-polar, long-chain alkane, and it
presents low viscosity. For these reasons, it had been established
beforehand that extraction with hexadecane is more appropriate
for the most volatile organic compounds. In this way, the experiment
provided more information about the adsorbed organic
compounds.The extracts were analysed by GC/MS (an Agilent 6890 N gas
chromatograph interfaced to an Agilent 5973 N quadrupole
mass-selective detector); an Agilent DB-624 capillary column
(30 m 0.25 mm and a film thickness of 1.4 lm) was used; Toluene
D-8 and 4-bromofluorobenzene were employed as internal
standards. We used the NIST Library to identify possible compounds
and obtained a high percentage of coincidence between
the mass spectrum of the detected and the proposed compounds.
Where the peaks of several compounds overlapped, identification
was based on an analysis of boiling points.
Fig. 2 shows the variation of the boiling points obtained from
literature for the different compounds proposed using the NIST
library vs. the retention times of these compounds in the GC column,
in order to test the proposed compounds follow a consistent