Method Statement PAHs by GC/MS
@(#) Uncontrolled Document pahgcms.html Version 1.1 Last
Revised on 12/09/02
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 target polyaromatic
hydrocarbons (PAHs) in soils and waters by solvent
extraction/concentration followed by analysis of extracts by gas
chromatography with mass spectrometeric detection (GC/MS).
Principle
Target PAHs are extracted from an aliquot of the test sample with
dichloromethane (in triplicate), after the addition of a mixture of
deuterated PAHs to the test sample. The extracts are then combined
and reduced in volume to 1ml. The extracts are then analysed by GC/MS
in the selected ion recording mode. This is normally performed at
unit mass resolution, but if low levels are required analysis is
performed at high resolution using a sector mass spectrometer.
Soil samples
0.1 to 10 g aliquots of dried and ground samples are spiked with
labelled internal standards then extracted by sonication with three
lots of dichloromethane. The three extracts are combined and reduced
in volume to circa 1 ml. The PAHs are then analysed by GC/MS.
Water samples
10ml to 1l aliquots of the shaken sample are taken then extracted
by liquid/liquid techniques with dichloromethane, after addition of
labelled internal standards. The extracts are combined then analysed
as for the soils.
Performance
Characteristics
Substances Determined
This method is suitable for the analysis of the 'EPA 16' PAHs.
These are naphthalene, acenaphthene, acenaphthylene, fluorene,
phenanthrene, anthracene, pyrene, fluoranthene, chrysene, benz(a)
anthracene, benzo(b)/(k) fluoranthene, benzo(a)pyrene,
dibenz(ghi)perylene, indeno(1,2,3,-cd)pyrene and dibenz(a.h)
anthracene. Other PAHs may be determined by the method provided
suitable standards and validation have been performed.
Range of Application
Limit of Detection
Soils 0.01-0.1 mg/kg
Waters 0.01 ug/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 Spectrometery (GC/MS).
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