Grease by EPA 1664 Replaces 418.1/ 413.1
The ozone destroying TPH 418.1 and Oil & Grease 413.1 methods have both been replaced by a single method, EPA 1664. The impetus for this change is that the 418.1/413.1 methods utilize Freon as the extraction solvent. The use of Freon has potentially serious consequences to our atmospheric ozone layers. The production of Freon is currently being phased out. The EPA has spent a number of years researching alternative solvents and finally settled on n-Hexane as the solvent that most closely approximates the results of the Freon extractions.
The new Oil & Grease analysis is similar to the old technique, but is inherently more difficult because n-Hexane and Freon have different densities. This results in vastly different handling procedures during the extraction process. Both the old and the new methods are gravimetric (weight based) techniques. The solvent resulting from the extraction is evaporated and the remaining material weighed
The new TPH method is very different from the old method. Not only has the solvent changed, the results are determined gravimetricly instead of with the Infrared Spectrophotometer as with the 418.1 method. This will make the new technique even less useful for volatile compounds because they will be lost when the solvent is evaporated.
Practically speaking, one should expect results from the 1664 Oil & Grease test to be similar to the 413.1 procedure in most cases. There could however be significant changes in the results depending on the characteristics of the sample matrix. The 1664 TPH results will be similar to the 418.1 results for heavier hydrocarbons, but not for the lighter/volatile constituents in the gasoline range, since the method now requires that the solvent be evaporated.
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Speciation Of Metals: ChromiumSampling 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