Links to Related Sites

Compound Lists

Phase Facts:

Speciation of Metals: Chromium

Sampling Volatiles In Soil by 5035

MTBE - The Next Challenge

Utilizing TPH Methods Effectively

TPH Method Overlap

Specific Petroleum Compound Testing

TPH 1664 vs. 413.1 and 418.1

TCLP vs. SPLP Extraction Procedures

Analyzing for Metals by ICP/MS

ICP/MS Qualitative All Elements Scan

A lot of misconceptions still exists about total petroleum hydrocarbon (TPH) analysis. Unfortunately, this prevalent area of environmental laboratory analysis remains the least consistent among laboratories. For ten years this has been a predominant area of focus for Phase.

TPH determined by Gravimetric (weight-based) method (EPA 1664) Heavier hydrocarbons above # 6 fuel oil do not resolve well on the gas chromatograph used for the 8015B TPH methods. Consequently, the TPH 1664 method remains the optimal choice when the quantitation of heavier hydrocarbons is required. The limitations of this method are three fold. First, this method provides quantitation information only, no hydrocarbon identification information is available. Second, due to the hexane solvent extraction method utilized, lighter gas range hydrocarbons are usually lost. Third, on soil samples this method is susceptible to some interference’s due to the chemical/physical nature of the soil that can yield false positive results.

TPH by Gas Chromatograph (EPA 8015B) is the predominant test currently utilized for petroleum hydrocarbon analysis. There are two basic versions of this test employed by laboratories (with many variations on the theme). Both versions utilize a sensitive instrument called a gas chromatograph (GC) to provide quantification as well as hydrocarbon identification information. The GC is not subject to interference’s common to the TPH 1664 method.

The two basic versions of the 8015B method are:

• Volatile TPH (TPH gasoline range or GRO) relies on a device that subjects the sample to heat and a constant stream of helium, designed to drive lighter, volatile hydrocarbons out of the sample.
• Extractable TPH (TPH diesel range or DRO) relies on a methylene chloride solvent extraction to "wash" heavier hydrocarbons from the sample. Lighter, "gasoline range" hydrocarbons are usually lost in this process.