Trihalomethanes (THM) measurement context
EPA Method 524.2, purge and trap gas chromatography/mass spectrometry (GC/MS): an inert gas is bubbled through the sample, the volatile compounds are caught on a trap, then released into the gas chromatograph and identified and measured by their mass spectra. The four trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane and bromoform) are reported individually and as total trihalomethanes, in µg/L.
Volatile organic compounds (VOC) measurement context
EPA Methods 524.2 and 524.3, purge and trap GC/MS, the same technique as the trihalomethane test. The regulated drinking-water volatile compounds, such as benzene, trichloroethylene, tetrachloroethylene and vinyl chloride, are identified by their mass spectra and reported in µg/L. EPA 524.3 is the newer revision of the method. Pesticides and herbicides
Provide the compound list
A class name does not establish every target included. Specify the compounds, applicable drinking-water program and reporting limits; use the prescribed bottle and handling plan for the scope.
Include the complete project requirement
Provide the matrix, target analytes, required method, fraction, units and reporting limits. Include the permit or monitoring instructions where results will support a regulatory submission. Naming this method does not establish blanket compliance eligibility.
Resolve collection before sampling
Use the bottle, preservation and delivery instructions assigned to the agreed scope. Identify each location and collection time, and document any deviation. The final analytical plan must fit the submitted material and its intended use.
Related testing & guidance
Technical & service references
Vanguard service detailsSource review: November 8, 2026. The agreed method and project scope govern the testing.