Method detection limits for EPA method 8015 diesel range organics

Scope

This application note will outline the appropriate solid phase extraction techniques for selected diesel range organic compounds as outlined in EPA method 8015C using Biotage automated or manual SPE solutions and DryVap™* Sample Concentrator. The first section will highlight the use of the Biotage® Horizon 5000 fully automated extraction system and the method used for this application. Additionally, there will be an Application Modification section that will highlight the use of the Biotage® VacMaster™ Disk vacuum manifold for this application.

*The DryVap™ system has been discontinued. We recommend using the TurboVap® evaporation systems for achieving equivalent results.
 

Introduction

One of the most frequently desired quantities in environmental chemistry is the amount of diesel range organics (DROs) contained within a sample. The analysis of DROs is performed in almost every major environmental laboratory under the EPA Method 8015. This method is commonly used to determine the contamination of alkanes from C10 to C28 caused by leaky underground storage containers. In addition to testing under Method 8015, many state-run environmental agencies have used Method 8015 as the foundation for their own, more in depth, methods; for example, the Massachusetts VPH and EPH methods and the Florida TRPH method.

The simplicity of EPA Method 8015 lends itself easily to automation. This application note outlines how to perform a Method Detection Limit (MDL) study utilizing the Biotage® Horizon 5000 automated extraction unit. The drying and concentration of the final extract was performed using the DryVap™ Concentrator System with DryDisk® technology. Final analysis was done using a gas chromatograph (GC) with flame ionization detector (FID).
The Biotage® Horizon 5000 is an automated solid phase extraction system specifically designed to extract a wide range of target analytes from both influent and effluent sample matrices. The 5000 software is a controller system which provides a simple yet elegant method of interacting with up to four extractor units. The DryVap™ Concentrator System used in conjunction with DryDisk® allows for an automated way to both dry and concentrate a sample extract.

Instrumentation

• Biotage Instruments
  »  Biotage® Horizon 5000 Automated Extraction System
  » Atlantic® DVB SPE Disk
  » DryVap™ Concentrator System
  » DryDisk® Solvent Drying System
• GC-FID (Flame Ionization Detector)
• Diesel and Motor Oil Standard
• 1-Chlorooctadecane & O-Terphenyl Surrogate Spike
  
  

Method summary

1. Purge the instrument using the method in table 1.
2. Spike the Diesel standard into one sample and Motor Oil standard into a second sample. Add both surrogates into each sample.
3. Obtain 1 L water samples and acidify with HCl to
4. Extract the samples using the Biotage® Horizon 5000 and the method shown below in table 2.
5. Dry and concentrate the extracts using the DryVap™ settings shown in table 3 to a final volume of 5 mL.
6. Perform the final analysis using GC-FID.
7. To complete the IDOC study, extract four replicates of each type using steps two through six
8. To complete the MDL study, extract seven replicates of each type using steps two through six over three, non-consecutive, days. Final concentration of Diesel is 0.5 mg/L and Motor Oil is 0.8 mg/L.
   
   

Acknowledgements

Biotage would like to thank Randall Heu and Hawaiian Electric Company for their assistance in developing this method.

Application modifications

Biotage® VacMaster™ Disk method summary

The procedure is the same as that outlined in the previous section. However, use the method found in this section for implementation using the Biotage® VacMaster™ Disk manifold.

1. Repeat the following steps for each active Biotage® VacMaster™ Disk station.
2. Setup the VacMaster Disk manifolds ensuring all waste lines and vacuum lines are attached. Set the vacuum pump to -24”Hg.
3. Prepare the disk holder assembly (47 mm): ensure the support screen is flat in the centre of the disk holder. Place the Atlantic® DVB Disk on top of the support screen with the ripples of the disk on top and add any prefilters on top of the disk. Place the disk holder assembly on the VacMaster Disk manifold ensuring there is a tight seal with the luer fitting.
4. If using the multifunnel, place onto the disk holder assembly. If not using the multifunnel, omit those directions throughout the method.
5. Condition the SPE Disk:
   a. Guide for each conditioning step in table 4 below:
   
   i. Measure the appropriate VOLUME of SOLVENT into a graduated cylinder and pour into the disk holder assembly.
   ii. Using a Nalgene Wash Bottle (phthalate free), rinse the multifunnel and disk holder in a circle for about 3 seconds using the same SOLVENT (approximately 5 additional mL).
   iii. SATURATE the disk for the time indicated (in SECONDS). (Saturate means: quickly turn the knob to the appropriate waste destination and back to the “OFF” position. This brings the solvent into the disk media bed).
   iv. SOAK the disk for the time indicated in SECONDS).
   v. DRAIN to the appropriate waste destination for the time indicated (in SECONDS). Switch to the “OFF” position.
   
   
6. Load the Sample:
   a. For multifunnel: quickly and efficiently angle the bottle to rest on the multifunnel upside-down.
   
   b. For no multifunnel: pour a portion of the sample into the disk holder.
   
   c. Adjust the vacuum between -10”Hg and -15”Hg for sample load (please note, if the sample is flowing too slowly, the vacuum can be increased). Drain the sample to “AQUEOUS” waste. Continue to pour the sample into the disk holder ensuring the disk does not go dry or overflow for the duration of sample load.
7. Air Dry the SPE Disk:
   a. Return the vacuum to -24”Hg and continue to air dry the SPE disk to “AQUEOUS” waste for an additional 60 SECONDS. Switch to the “OFF” position.
   
   b. Remove the sample bottle from the multifunnel if it was used.
8. Elute the SPE Disk: (Please note: the elution solvent will go into the collection flask inside the chamber, not to waste containers).
   a. Place a clean 125mL 24/40 tapered Erlenmeyer flask into the Biotage® VacMaster™ Disk collection chamber. Place the cover on the chamber. Remove the disk holder assembly and place the disk holder assembly into the luer fitting on top of the collection chamber. Attach the luer fitting of the collection chamber assembly onto the manifold.
   
   b. Guide for each elution step in table 5 below:
   
   i. Measure the appropriate VOLUME of SOLVENT into a graduated cylinder, pour into the sample bottle, and swirl around. Pour the solvent in the sample bottle into the disk holder assembly.
   ii. Using a Nalgene Wash Bottle (phthalate free), rinse the multifunnel and disk holder in a circle for about 3 seconds using the same SOLVENT (approximately 5 additional mL).
   iii. SATURATE the disk for the time indicated (in SECONDS) to “ORGANIC”.
   iv. SOAK the disk for the time indicated (in SECONDS).
   v. DRAIN to “ORGANIC” for the time indicated (in SECONDS). Switch to the “OFF” position.
   vi. Remove the chamber lid to release the vacuum from inside the chamber.
   
   

Literature number: AN056