GC–MS Analysis of Volatile Organic Compounds in Drinking Water: Productivity Solution for U.S. EPA Method 524.2

The GC–MS analysis of volatile organics in drinking water according to United States Environmental Protection Agency (US EPA) Method 524.2 offers a number of analytical challenges, ranging from water handling to very low target compound concentrations. The Thermo Scientific DSQ II GC–MS system provides excellent sensitivity and allows for the use of a 5 mL purge. To allow laboratories to realize this improved performance and productivity a comprehensive resource was created for Method 524 and made available online.

Experimental Conditions

In full-scan mode, the DSQ™ II has excellent sensitivity, allowing a split injection of 80 to 1 to be made on a conventional split/splitless injector. The high split ratio minimizes adverse effects of co-eluting water inherent in this method of sample transfer. The column flow was set to a constant pressure of 25 psi. A 20 m × 0.18 mm TRACE™ TR-524 column with a film thickness of 1.0 ?m was used for the analytical column. The DSQ II mass spectrometer was tuned to meet the criteria for the tuning compound 4-bromofluorobenzene (BFB) using Target Tuning software.

Table I: Highlights the calibration, daily calibration check, and detection limit study results for selected compounds.

Results

The analysis of 84 volatile organics was performed in 11 min. Over a concentration range of 0.4 to 40 μg/L, the compounds analyzed had an average % RSD of 6. The average method detection limit was 0.095 μg/L, using a 5 mL sample volume. A daily calibration check standard was run at 4 μg/L. The average difference was 2.0%.

Conclusions

The Method 524 Productivity Solution enables fast chromatography, with a short run time of 11 min. A high-throughput lab can easily process 36 samples or more per 12 h shift. Combined with a fast scanning rate, this method features excellent separation and sensitivity and generates MDLs required by the EPA method. Using the online productivity solution the DSQ II becomes a dedicated analyzer for volatiles, helping laboratories to achieve three times the sample throughput of standard methodologies.

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