Method Statement Total Petroleum Hydrocarbons
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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 method describes the determination and speciation of Total
Petroleum Hydrocarbon (TPH) in soils/sediments and waters by GC/FID.
Principle
The TPH is extracted into a dichloromethane and analysed by
capillary gas chromatography with flame ionisation detection.
Quantitation is performed against an external standard (diesel
standard). Speciation is performed by comparison of the
chromatograms obtained to those from a set of standards which contain
straight chain aliphatic hydrocarbons, ranging from C10 to
C28, The results are expressed as carbon number ranges.
Soil samples
10g of sample (as received) is extracted with dichloromethane.
Impurities are removed from the extract with sodium sulphate and
silica, they are reduced in volume and analysed by GC/FID.
Water samples
250ml homogenised sample extracted with dichloromethane.
Impurities are removed from the extract with sodium sulphate and
silica, they are reduced in volume and analysed by GC/FID.
Performance
Characteristics
Substances Determined
For the purposes of this method TPH is defined as all hydrocarbons
extractable by the method within the carbon range from circa C8
to circa C35. This range is appropriate for the
determination of contamination caused by products such as diesel,
fuel, heating and lubricating oils, paraffin/kerosene and white
spirit. This method is not suitable for the analysis of
gasoline range organic compounds.
Range of Application
Soils 1 to 1000 mg/kg
Waters 0.05 to 100 mg/l
Limit of Detection
Soils 1 mg/kg
Waters 0.05 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
Analysis of Petroleum Hydrocarbons in Environmental Media, Total
Petroleum Hydrocarbon Working Group Series, Volume 1, March 1998.
US EPA Method 8015B, Revision 2, December 1996 “Nonhalogenated
Volatile Organics Using GC/FID”, SW-846, 3rd Edition.
TNRCC Method 1006 “Characterisation of C6 to C35
Petroleum Hydrocarbons in Environmental Samples”.
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