Determination of Organic Compounds in Drinking Water Using Atlantic SPE Disks for EPA Method 525.2

EPA Method 525.2 describes the procedure to determine low ppb levels of semi-volatile organic material in drinking water using solid phase extraction (SPE) or liquid-solid extraction (LSE) techniques. The City of Fort Worth, Water Department implemented an automated SPE process for the analysis of semi-volatiles by EPA Method 525.2, using the Atlantic "Certified for Automation" SPE Disk for EPA Method 525.2. Ethyl acetate, methanol, and water were used to condition the Atlantic disk prior to the extraction step. The extraction solvents used were a 1:1 mixture of methylene chloride and ethyle acetate. Extracts were then analyzed by GC–MS using a splitless injection technique.

Automated sample handling equipment manufactured by Horizon Technology, Inc. was used, including the SPE-DEX® 4790 Automated Extraction System, the Envision™ Platform Controller, and the DryVap™ Automated Drying and Concentration System. These units are designed to streamline the sample handling required for analyzing environmental samples.

The SPE-DEX 4790 provides automated extraction of liquid samples by solid phase extraction methods, handling samples that range from 20ml to 4L. The Envision Platform provides a user-friendly, web-based controller capable of interacting with up to eight extractors via a PC. The DryVap Concentrator System provides automatic sample drying with a patented membrane technology and automatically concentrates each dried extract by applying heat, vacuum, and sparge flow for up to six samples at once.

Instrumentation

• Horizon Technology SPE-DEX 4790 Automated Extractor System

• Horizon Technology Envision Platform Controller

• Horizon Technology DryVap Concentrator System with Dry Disk™ Separation Membranes

• Atlantic "Certified for Automation" SPE Disk for EPA Method 525.2 (47 mm)

Method Summary

1) A 1L aliquot of sample is used.

2) Adjust samples pH to <2.

3) Spike surrogate and internal standard compounds into samples.

4) Spike analyte standards into samples.

5) Start extraction method, collect extract (approx 30 ml).

6) Add extract to the Dry Disk holder and start concentration process on the DryVap system.

7) Concentrate the extract to less than 1.0 ml and quantitatively bring the extract volume to 1.0 ml (DryVap concentration vessels are graduated to 0.5 ml and 1.0 ml).

8) Transfer a portion of the extract to a GC vial with insert.

9) Analyze by GC–MS.

Results

Ultra-Pure (UP) water was spiked with 525.2 standard at a theoretical concentration of 5.0 ppb. A subset of the results for the Atlantic disk are listed above in Table I. Forty-two compounds were included in the target compound list. The table shows the compound names, amount recovered, and percent recovery.

Table I

The Atlantic disk had a recovery range between 61%–122%. The Atlantic SPE Disk for EPA Method 525.2 is designed and certified for EPA Method 525.2 by Horizon Technology to guarantee the highest quality results. †Note the excellent recovery for Prometon with an acidic extraction (pH<2). This analyte usually requires a separate extraction under neutral pH conditions. Download the complete application note at: www.horizontechinc.com/htmpages/forms/applications_form_525.htm

Conclusions

The data demonstrated that the Atlantic "Certified for Automation" SPE Disk for EPA Method 525.2, and the equipment used in this study, was capable of fully automating EPA Method 525.2, and providing excellent results.

Acknowledgements

Our thanks to Dr. Johnny Skelton, PhD, from the City of Fort Worth, Water Department, Centralized Laboratory Services for his time and assistance with this study.

Horizon Technology, Inc.

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