2.3. Chemical analysis
In order to chemically verify the stock concentration (highest test concentration
used to prepare other test concentrations), samples were taken for analysis at
days 0 and 10. The samples were taken by transferring approximately 25 g of test
sediment to hexane-rinsed 60 ml glass jars and the samples were then immediately
frozen at 20 1C prior to analysis.
The determination of PAH concentrations in spiked test sediments was carried
out using established methods that use GC/MS in full-scan, electron impact mode.
The method is fully described elsewhere (Kelly et al., 2000). Briefly, sediments are
subjected to alkaline saponification using methanolic KOH and the digests solvent
extracted with pentane to recover PAH. Extracts are cleaned-up using alumina
column chromatography, reduced in volume and transferred to an injection vial.
Deuterated analogues of the parent PAH determined are used as surrogate
standards.
All samples are run under an analytical quality control (AQC) protocol, which
involves analysing procedural blanks and reference materials within each sample
batch. In this study we used a marine sediment reference material (HS-6) from the
Canadian National Research Council, produced within its marine analytical
chemistry standards programme. A detection limit of 0.1 mg/Kg dry weight in
sediment for each compound or class is one, which we have found readily
achievable in all samples, and that provides an adequate detection capability for
interpretation of the data.
2.3. Chemical analysisIn order to chemically verify the stock concentration (highest test concentrationused to prepare other test concentrations), samples were taken for analysis atdays 0 and 10. The samples were taken by transferring approximately 25 g of testsediment to hexane-rinsed 60 ml glass jars and the samples were then immediatelyfrozen at 20 1C prior to analysis.The determination of PAH concentrations in spiked test sediments was carriedout using established methods that use GC/MS in full-scan, electron impact mode.The method is fully described elsewhere (Kelly et al., 2000). Briefly, sediments aresubjected to alkaline saponification using methanolic KOH and the digests solventextracted with pentane to recover PAH. Extracts are cleaned-up using aluminacolumn chromatography, reduced in volume and transferred to an injection vial.Deuterated analogues of the parent PAH determined are used as surrogatestandards.All samples are run under an analytical quality control (AQC) protocol, whichinvolves analysing procedural blanks and reference materials within each samplebatch. In this study we used a marine sediment reference material (HS-6) from theCanadian National Research Council, produced within its marine analyticalchemistry standards programme. A detection limit of 0.1 mg/Kg dry weight insediment for each compound or class is one, which we have found readilyachievable in all samples, and that provides an adequate detection capability forinterpretation of the data.
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