USGS-NWQL: O-1433-01:  Wastewater compounds in water by SPE and GC/MS

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Official Method Name
 Determination of Wastewater Compounds by Polystyrene-Divinylbenzene Solid-Phase Extraction and Capillary-Column Gas Chromatography/Mass Spectrometry
Current Revision
2001
Media
 WATER
Instrumentation
 Gas Chromatography with Mass Spectrometry Detection
Method Subcategory
 Organic
Method Source
  USGS-NWQL
Citation
 Zaugg, S.D., Smith, S.G., Schroeder, M.P., Barber, L.B., and Burkhardt, M.R., 2002, Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory--Determination of wastewater compounds by polystyrene-divinylbenzene solid-phase extraction and capillary-column gas chromatography/mass spectrometry: U.S. Geological Survey Water-Resources Investigations Report 01-4186.
Brief Method Summary
 Water samples are filtered in the field by using glass-fiber filters (0.7-um nominal pore diameter) to remove suspended particulate matter (Sandstrom, 1995) before they are sent to the NWQL. Filtered 1-L water samples are extracted with disposable, polypropylene SPE cartridges that contain polystyrene-divinylbenzene phase. The SPE cartridges are dried thoroughly by using a flow rate of 2 L/min of pressurized nitrogen, which takes about 45 minutes. After the SPE cartridges have dried, the sample bottles are rinsed thoroughly with a mixture of 15 mL dichloromethane (DCM) and diethyl ether (EE), at 4:1. The DCM-EE rinsate also is used to elute sorbed compounds from the corresponding SPE cartridges. Next, the extract is evaporated by using a gentle stream of nitrogen to a final volume of 0.4 mL and then is transferred to an autosampler vial that contains a 400-mL glass insert. Finally, the concentrated extracts are deter-mined by capillary-column gas chromatography/mass spectrometry (GC/MS).
Scope and Application
 This manual method is suitable for the determination of microgram-per-liter concentrations of compounds in filtered wastewater and natural-water samples. The method is applicable to compounds that are efficiently partitioned from the water phase onto the polystyrene-divinylbenzene (PSDVB) organic phase, and are sufficiently volatile and thermally stable for gas chromatography. Samples are filtered to remove suspended particulate matter, so this method is suitable only for dissolved-phase compounds.
Applicable Concentration Range
 0.50 - 4.0 (undiluted)
Interferences
 Organic compounds that have gas-chromatographic retention times and characteristic ions with a mass identical to those of the compounds of interest might interfere, and because of the complex nature of wastewater, there are often unknown compounds that interfere. Phthalates and preservatives (BHT and related compounds) in the cartridge material often contribute to low-concentration contamination. Samples, collection equipment, or SPE cartridges that are handled improperly also might become contaminated with soaps, caffeine, and fragrances.
Quality Control Requirements
 First, the sample matrix must be consistent with the requirements of the method (filtered water). Problematic sample matrices will affect the performance of the method during sample preparation and analysis. Extremely dirty sample matrices, such as raw sewage, are discouraged because they contaminate sample preparation equipment and instrumentation, thus affecting the results of subsequent samples. Sample extract(s) are analyzed in an instrument batch or sequence to provide additional information for quality assurance and facilitate corrective actions that might be required if performance criteria are not met. The analytical sequence includes a set spike and blank sample, as well as bracketing continuing calibration verification solutions (CCVs) to check periodically at designated intervals (10 environmental samples or less) that the instrument is in compliance with initial calibration criteria. A low-concentration standard equivalent to 1 ug/L (or less) is analyzed in each sequence after the environmental samples to ensure that instrument sensitivity is maintained throughout the sample set. If available, field matrix spike samples at concentrations between 2 and 5 times the expected MDL also can be analyzed to ensure method sensitivity for different sample matrices.
Sample Handling
 1L GCC - This schedule consumes the entire sample. Description: 1 L Glass bottle, amber bottle baked at 450 deg C by laboratory - SOME GCCs should be filtered. CHECK METHOD REFERENCE OR EMAIL LABHELP@USGS.GOV FOR FILTERING REQUIREMENTS. Treatment and Preservation: DO NOT RINSE BOTTLE. Do not fill bottle beyond shoulder, reagents must be added to the sample at the NWQL before analyses. Chill sample and maintain at 4 deg C, ship immediately.
Maximum Holding Time
 14 days from sampling
Relative Cost
 $201 to $400
Sample Preparation Methods
 USGS-WRIR 95-4105
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