Method Statement SVOC Targets
@(#) Uncontrolled Document svoctargets.html Version 1.4 Last
Revised on 11/20/02
Contents
Introduction
Principle
Performance
Characteristics
Range
of Application
Limit of
Detection
Analytical
Quality Control
References
Introduction
The performance of this method is validated in accordance with
internationally recognised procedures.
This procedure describes the determination of semi-volatile
organic compounds in soils and waters by solvent
extraction/concentration followed by analysis of extracts by gas
chromatography mass spectrometry.
Principle
An aliquot of the sample is spiked with isotopically labeled
internal standards and then the semi-volatile organic compounds are
extracted into a solvent. These extracts are then concentrated by
evaporation and analysed by scanning Gas Chromatography-Mass
Spectrometry (GC/MS). Deuterated internal standards are added to
all test samples, spikes and blanks before analysis. The quantitative
results are then corrected for the recovery of these standards.
In instances where a compound is not present in the calibration
standards, a tentative identification and result are produced based
upon a comparison of the mass spectra obtained with those found in
the NIST mass spectral databases. Such tentative results are subject
to confirmation by the analyst.
Soil samples
0.1 to 10 g aliquots of dried and ground samples are taken, spiked
with labeled internal standards, then extracted under ultrasonic
agitation with three aliquots of dichloromethane:acetone 50:50. The
three extracts are combined, reduced in volume to circa 1 ml for
GC/MS analysis.
Water samples
10ml to 1l aliquots of the shaken sample are taken, spiked with
isotopically labeled internal standards, then extracted by
liquid/liquid techniques with dichloromethane. Usually, the sample
is extracted with six aliquots of solvent as follows. The sample is
acidified to a pH of less than 2 and three extracts are taken, the
sample is then made alkaline to a pH greater than 11 and a further
three extracts are taken. The six extracts are combined then reduced
in volume by evaporation to circa 1ml for GC/MS analysis.
Performance
Characteristics
Substances Determined
A range of semi-volatile organic compounds, ranging in boiling
points from circa 180 C to 600 C. Standard target suite includes
polyaromatic hydrocarbons (PAHs), phthalates, phenols and other
priority pollutants.
Range of Application
Limit of Detection
Soils 0.1 mg/kg
Waters 0.01 mg/l
Analytical Quality
Control
Analytical quality control is maintained by a number of measures:
Multi-point calibration with
authentic standards (with defined minimum performance
characteristics)
Analysis of control samples within
each analytical batch, such as independent standards, matrix spikes
or reference materials
Analysis of reagent/method blanks
within each analytical batch
Ongoing quality assured by the use
of control charts in conjunction with warning and action limits for
the QC sample data
Participation in external
proficiency testing and interlaboratory schemes such as LGC CONTEST,
HSE WASP, CSL FAPAS
References
US EPA Method 8270, Revision C, Semivolatile Organic Compounds by
Gas Chromatography-Mass Spectrometry (GC/MS).
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