GC/HPLC Analyses of Organic Compounds in Drinking Water: US EPA Procedures

Significance of the Topic

Ensuring safe drinking water requires sensitive and accurate detection of trace organic contaminants. The US EPA Series 500 methods establish standardized protocols for monitoring a broad range of volatile and nonvolatile organics, supporting regulatory compliance and public health protection.

Study Objectives and Overview

This whitepaper reviews the US EPA’s Series 500 procedures for analyzing organic compounds in drinking water by gas and liquid chromatography. It summarizes sample preparation techniques, chromatographic separations, detection modes, and demonstrated performance using Supelco and OI Analytical products.

Methodology and Instrumentation

Sample preparation addresses both volatile and nonvolatile analytes:

• Purge-and-trap concentration on carbon adsorbent traps (e.g. VOCARB™ 4000) followed by thermal desorption.
• Solid phase extraction (SPE) with C18 or ion-exchange disks (ENVI™-18, ENVI-8) for semi-volatiles, pesticides, herbicides, and other synthetic organics.
• Liquid–liquid extraction for organohalide pesticides and PCBs using methylene chloride or hexane.

Chromatographic separation and detection include:

• Capillary GC columns: VOCOL™ (wide bore for VOCs), PTE™-5, SPB™-1, SPB™-1701, SPB™-210, SPB™-2401.
• HPLC columns: C18 reversed-phase (SUPELCOSIL™ LC-18), PAH-selective phases, ion-exchange columns for glyphosate.
• Detectors: FID, ECD, nitrogen-phosphorus or thermionic (TSD), photoionization (PID) and electrolytic conductivity (ELCD) in tandem, mass spectrometry (GC/MS), and diode array UV for HPLC.
• Instrumentation examples: OI Analytical Model 4460A/4440 purge-trap with tandem PID/ELCD, Tekmar LCS 2000, conventional GC/MS and GC/ECD systems.

Main Results and Discussion

Chromatographic data demonstrate efficient separation of 60 EPA-regulated purgeable organics with VOCOL columns and GC/MS, complete recovery of volatile priority pollutants at low ppb levels, and reliable quantitation of pesticides, PCBs, phthalates, phthalic and adipic esters, and polycyclic aromatic hydrocarbons across diverse matrices. Alternative adsorbents and wide bore columns improved desorption efficiency, reduced background, and eliminated cryofocusing requirements.

Benefits and Practical Applications

The Series 500 methods provide laboratories with robust, validated workflows for routine monitoring of drinking water contaminants. The flexibility to use alternative sorbents, paired with high-temperature traps and inert low-bleed columns, enhances throughput, reduces carryover, and meets stringent quality control criteria.

Future Trends and Applications

Emerging developments include:

• Tailored adsorbent materials and microfabricated traps for broader analyte coverage.
• Integration of fast GC and tandem MS/MS for ultra-trace analysis.
• Automated on-line SPE-GC and GC×GC-TOF for comprehensive screening.
• Green sample preparation techniques minimizing solvent use.

Conclusion

US EPA Series 500 procedures, supported by modern chromatographic technology and sample preparation media, deliver precise, reproducible analyses of a wide spectrum of organic contaminants in drinking water. Continuous innovations in adsorbents, columns, and detectors will further improve laboratory efficiency and detection capabilities.

References

• [1] US EPA Methods for the Determination of Organic Compounds in Drinking Water, Series 500, including Methods 502.2, 524.2, 525, 531.1, 547, 550, 551. National Technical Information Service, PB 92-207703.
• [2] Technical Note for Drinking Water Methodology Amendments. US Department of Commerce NTIS Document PB95-104766.