Dear Sir/Madam:

The Massachusetts Department of Environmental Protection (MADEP) has recently issued a draft procedure for the analysis of petroleum hydrocarbons in air and soil gas samples, as a complement to the Volatile Petroleum Hydrocarbon (VPH) and Extractable Petroleum Hydrocarbon (EPH) methods previously issued by the agency for the characterization of soil and water samples. The new procedure entitled "Method for the Determination of Air-Phase Petroleum Hydrocarbons (APH), Public Comment Draft 1.0" may be downloaded (file to download:PDF 220 KB | MS Word 477 KB )).

MADEP is seeking comment and input on this draft document from the laboratory, consulting, regulated, and environmental communities. The Department is also planning to conduct a Round Robin testing program during the Spring of 2000 to further evaluate and validate this procedure, and is looking for laboratories who would be willing to participate is such an effort.

Background

In a document dated August 1994, MADEP presented a toxicological approach to evaluate the potential health effects associated with human exposure to petroleum hydrocarbons. This approach requires knowledge of the distribution of aliphatic and aromatic hydrocarbons within environmental media of interest (i.e., water, soil, and/or air). Information of this nature cannot be obtained from existing analytical methods, including those "TPH" methodologies in common use.

MADEP has previously developed and released two analytical procedures that are capable of producing health-relevant data in soil and water matrices. The Volatile Petroleum Hydrocarbon (VPH) method was developed to characterize potential health effects associated with releases of light petroleum products such as gasoline; the Extractable Petroleum Hydrocarbon (EPH) method was developed to evaluate potential health effects from releases of heavier-molecular-weight products such as fuel oil.

The draft Air-Phase Petroleum Hydrocarbon (APH) method is designed to measure the gaseous-phase concentrations of volatile aliphatic and aromatic petroleum hydrocarbons in air and soil gas. Volatile aliphatic hydrocarbons are collectively quantitated within two carbon number ranges: C₅ through C₈, and C₉ through C₁₂. Volatile aromatic hydrocarbons are collectively quantitated within the C₉ to C₁₀ range. The method also identifies and quantifies the individual concentrations of 10 target analytes, including MtBE, BTEX, and certain naphthalenes.

Request for Comments

Comments are requested on all facets of the proposed method. Items and issues of particular interest to the agency are summarized in Attachment 1.

Round Robin Testing Effort

After receiving and reviewing comments on this draft method, a Round Robin testing effort will be conducted by MADEP to further evaluate and validate the procedure. This program is tentatively scheduled to be conducted during the Spring of 2000. Laboratories that are interested in participating in the Round Robin effort are encouraged to contact the Department as soon as possible.

Deadlines

The deadline to provide comments on the draft method, and express an interest in participating in the Round Robin testing effort is Wednesday, April 12, 2000. Please provide this information to John Fitzgerald at email address John.J.Fitzgerald@state.ma.us or mailing address MADEP, One Winter Street, Boston, MA 02108.

Your interest and comments in this matter are appreciated. If you have any questions, please contact John Fitzgerald at (978) 661-7702.

Very truly yours,

Deirdre C. Menoyo
Assistant Commissioner
Bureau of Waste Site Cleanup

Attachment 1: Request for Comments
APH Public Comment Draft 1.0

General
1.0 Is the approach technically sound?

2.0 Should additional sampling provisions and options be provided in the method?

2.1 bag samplers?
2.2 sorbent tube samplers?

3.0 Is the calibration technique appropriate?

3.1 use of methanol-based stock and primary dilution standards
3.2 generation of gaseous-phase standards
3.3 choice of calibration component standards

4.0 What should be the termination point of APH analysis? C12? Naphthalene? 2-methylnaphthalene? 1-methylnaphthalene?

4.1 desire to account for heavy-end hydrocarbon vapors observed on sample chromatograms vs. problems with accuracy and precision beyond naphthalene
4.2 limitations in canister samplers
4.3 application/required use of sorbent tube samplers for heavier molecular weight hydrocarbons

5.0 Are the QA/QC provisions appropriate? Too much? Too little?

6.0 Have method limitations been clearly articulated? Are there additional steps that can or should be taken to minimize interferences and/or enhance method utility?

7.0 Is the method practicable and cost effective?

7.1 implementability
7.2 costs

Draft SOP 1.0
1.0 Is the method clearly written and understandable?

2.0 Is there a need to standardize units of measurements?

2.1 volume of liquids and gases
2.2 pressure units

3.0 Are canister cleaning/preparation/sampling requirements and recommended procedures sufficiently precise?

4.0 Are the calibration procedures clear?

4.1 liquid (methanol-based) stock and primary dilution standards
4.2 gaseous-phase APH working and calibration standards

5.0 Are data manipulation/adjustment procedures clear?

5.1 SOP equations and calculations
5.2 range adjustment for Target Analytes and C9-C10 Aromatic Hydrocarbons

6.0 Are required QA/QC procedures, requirements, and performance standards clear, appropriate, and reasonable?

8.0 Is the required Reporting Format in Appendix 3 appropriate?

9.0 Is the recommended SOP for sampling in Appendix 4 useful and appropriate?

Specific Issues
1.0 GC/MS TECHNIQUE - Is the GC/MS technique presented in the method optimal and reliable?

1.1 Does the extracted ion technique accurately identify and quantify C9-C10 Aromatic Hydrocarbons without interference or unacceptable positive or negative bias? Do the summed areas of ions 120 and 134 reliably and consistently quantitate the types and classes of aromatic hydrocarbons eluting from o-xylene to 1-methylnapthalene, based upon comparison to selected calibration standards?
1.2 Is the variability in GC/MS total ion response to specific aliphatic compounds significant? Does this variability allow quantitation of hydrocarbon mixtures in field samples with reasonable accuracy and precision?

2.0 DETECTION/REPORTING LIMITS - The draft SOP (see Sect 12.0) requires the derivation of a Reporting Limit for each Target APH Analyte and each hydrocarbon range, per the procedures previously articulated by MADEP in the VPH and EPH methods. Similar to the VPH/EPH methods, the RL for target analytes may not be set lower than the lowest calibration standard which is still within the linear range of the calibration curve. Is there any reason why such an approach is not appropriate for air analyses?

3.0 CALIBRATION STANDARDS - The draft SOP (see Table 9) specifies the use of 6 individual aliphatic component standards to determine a range response factor for C9-C12 Aliphatic Hydrocarbons, including 2,3-dimethylheptane and butylcyclohexane. However, because of the co-elution of p&m-xylenes and indene, respectively, with these two aliphatic standards, the range response factor for C9-C12 Aliphatics is actually calculated based upon the response of the 6 aliphatic compounds PLUS these three aromatic compounds. Is this acceptable? Note that the response factor for m&p xylenes is 30% higher than 2,3-dimethylheptane (which would lead to a more conservative range response factor for C9-C12 Aliphatic Hydrocarbons), while indene has a 37% lower response factor than butylcyclohexane (which would lead to a less conservative response factor for this range). Options could include: use of only 4 aliphatic standards for the for C9-C12 Aliphatic Hydrocarbons range by elimination of these co-eluting compounds (though this would eliminate a branched and cyclic alkane - major structural classes of petroleum products), or the designation of alternative aliphatic component standards.

4.0 DIFFERENTIAL PRESSURE MEASUREMENTS - The SOP relies on the use of differential pressure measurements to determine the volume of zero air introduced into SUMMA canisters and the resultant concentration of analytes in the APH working standards. Is this sufficiently precise? Should the method require the use of electronic pressure measurement devices, and/or mass flow controllers?

5.0 WATER VAPOR ISSUES - Are the effects/implications of water vapor sufficiently articulated and addressed in the SOP? With respect to soil gas sampling, and/or use of the Nafion dryer? Is the effect of the vapor pressure of water insignificant with respect to the calculation of APH working standard concentrations? Other effects/implications?