This can help you,

Methods for determining TPH in aqueous samples are discussed above in Section 3.3.1. The overall

method includes sample collection and storage, extraction, and analysis steps. Sampling strategy is an

important step in the overall process. Care must be taken to assure that the samples collected are

representative of the environmental medium and that they are collected without contamination. There are

numerous modifications of the EPA, American Public Health Association (APHA), and American

Society for Testing and Materials (ASTM) methods discussed above. Most involve alternate extraction

methods developed to improve overall method performance for TPH or replacement of the

chlorofluorocarbon solvents. SPE techniques have been applied to water samples (Schrynemeeckers

1993). Solvent extraction methods with hexane (Murray and Lockhart 1981; Picer and Picer 1993) or

methylene chloride (Mushrush et al. 1994) have been reported as well.

You can search references of DRO (Diesel Range Organics).

to determine,

use SPME / Headspace method for extraction as diesel is low boiler, avoid the evaporation loss while extraction.

or,

to estimate,

take 2:1 ,sample:solvent, in a separtiong funnel. solvents can be methlene chloride or pentan:diethyl ether (1:1), shake well for 5-6 min, with gas release, keep the mix for 5 min, with opened lid in a stand, separte the organic layer in a test tube / beaker, evaporate the solvent by room temp. for an hour/beyond. inject the sample into the GCMS/ GC

if the sample containing more analytes, we can use toluene / DMF/DMSO as solvent, but we can't concentrate the sample solution to improve the peak response.

i hope this helps!

Regards

Selvan

You can try to extract with CCl4, then analyze through IR (FTIR) looking the CH2/CH3 bands