Method 506

Determination of Phthalate and Adipate Esters in Drinking Water by Liquid-Liquid Extraction or Liquid-Solid Extraction and Gas Chromatography and Photoionization Detection


This method describes a procedure for the determination of certain phthalate and adipate esters in drinking water by liquid/liquid or liquid/solid extraction. This is a capillary column gas chromatographic (GC) method applicable to the determination of the compounds in ground water and finisheddrinking water. When this method is used to analyze unfamiliar samples for any or all of the compounds listed above, compound identifications should be supported by at least one additional qualitative technique. Method 525.2 provides gas chromatograph/mass spectrometer (GC/MS) conditions appropriate for the qualitative and quantitative confirmation of results for the analytes for this method, using the extract produced by this method. This method has been validated in a single laboratory, and method detection limits (MDLs) have been determined for the analytes. Observed detection limits may vary among waters, depending upon the nature of interferences in the sample matrix and the specific instrumentation used. A measured volume of sample, approximately 1 L, is extracted with methylene chloride followed by hexane using a glass separatory funnel. The solvent extract is isolated, dried and concentrated to a volume of 5 mL or less. The extract is further concentrated by using a gentle stream of nitrogen gas to reduce the sample volume to 1 mL or less. Alternatively, a measured volume of sample is extracted with a liquid-solid extraction (LSE) cartridge or disk. The LSE media are eluted with acetonitrile followed by methylene chloride (disk extraction) or with methylene chloride only (cartridge extraction). The eluant is concentrated using a gentle stream of nitrogen gas or clean air to reduce the volume to 1 mL or less. The analytes in the extract are separated by means of capillary gas chromatography using temperature programming. The chromatographically separated phthalate and adipate esters are measured with a photoionization detector, which is operating at 10 eV.


(EPA: Office of Water)

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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   Analytes stored are stable up to 14 days or longer. A 14-day maximum extract storage time is recommended.
Preservatives:   For sample dechlorination, add 80 mg sodium thiosulfate to the sample bottle at the sampling site. The samples must be iced or refrigerated at 4°C free from light from the time of collection until extraction.
Required Preps:   Glass bottle.
Collection Method:   Grab sampling
Analytical Methodology:   GC/PID (Photoionization Detection)
Documentation:   506

Analyte List*

Analyte Formula CAS Number Detection Limit
Di(2-ethylhexyl)adipate
C22H42O4
103-23-1
11.82
 µg/L
bis-(2-Ethylhexyl)phthalate
C24H38O4
117-81-7
2.25
 µg/L
Di-n-octyl phthalate
C24H38O4
117-84-0
6.42
 µg/L
Dimethylphthalate
C10H10O4
131-11-3
1.14
 µg/L
Diethylphthalate
C12H14O4
84-66-2
0.84
 µg/L
Di-n-butylphthalate
C16H22O4
84-74-2
1.23
 µg/L
Butylbenzylphthalate
C19H20O4
85-68-7
2.67
 µg/L

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.